Pathology – PESSI

An 8-year-old boy presents to the physician with complaints from his parents that he has had recurrent illness, clumsiness, and multiple episodes of pneumonia and diarrhea. He also says that he has trouble seeing things well in the dark. Other symptoms include white patches (keratinized epithelium) on the sclerotic coat (protection and covering of the eyeball) and conjunctival dryness. What is the most likely cause of these symptoms in this boy?

A 35-year-old lactose intolerant man presents to the outpatient clinic with complaints of numbness and tingling in his fingers and toes for the past month. He also complains of pain in his calf muscles while sleeping; the pain is severe enough to wake him up in the middle of the night. He is a software engineer and spends most of his time indoors. He has been smoking a pack of cigarettes daily for the past 10 years and occasionally drinks wine with dinner. His current medication regimen includes as needed ibuprofen and calcium supplementation. He does not take any other multivitamins. On examination, his pulse rate is 74/min, blood pressure is 128/67 mm Hg, respiratory rate is 16/min, and temperature is 37.6°C (99.7°F). He has tenderness in the proximal muscles of his upper and lower limbs. Sensory examination is normal. The rest of the physical examination is normal. X-ray imaging of his lower limbs shows features of demineralization. Which of the following sets of abnormalities are most likely occurring in this patient?

A 17-year-old girl is brought in by her mother due to rapid weight loss over the past month. The patient says she has been having episodes of diarrhea. She also says she has never had a menstrual period. The patient’s mother adds that the patient has been underperforming at school and acting very strangely at home. Her current BMI is 16.8 kg/m2. On physical examination, the skin on her limbs and around her neck is inflamed and erythematous. Her tongue is bright red and smooth. She states that over the last 2 weeks, she has been eating nothing but small portions of fruit. She is diagnosed with a vitamin deficiency. Which of the following statements is true about the vitamin that is most likely deficient in this patient?

A 25-year-old woman first presented to your clinic due to morning stiffness, symmetric arthralgia in her wrist joints, and fatigue. She had a blood pressure of 132/74 mm Hg and a heart rate of 84/min. Physical examination revealed tenderness to palpation of both wrists but full range of motion. Test results for anti-citrullinated protein antibodies were positive, and the erythrocyte sedimentation rate was above the normal range. She was started on methotrexate therapy. She returns for follow-up 2 months later and is found to have megaloblastic anemia. What is the mechanism of action of methotrexate?

A mother with HIV gave birth to a healthy boy 2 days ago. She takes her antiretroviral medication regularly and is compliant with the therapy. Before being discharged, her physician explains that she cannot breastfeed the child since there is a risk of transmitting HIV infection through breastfeeding, and tells her that the child can benefit from formula feeding. The physician stresses the importance of not overheating the formula, as vitamin C may be inactivated by overheating. Which process could be impaired if the mother boiled the water for formula longer than needed?

A graduate student at the biochemistry laboratory decides to research the different effects of vitamin deficiencies in mice by completely depriving the mice of one vitamin. The symptoms of this vitamin deficiency include hemolytic anemia and neuromuscular signs of ataxia and peripheral neuropathy. Further blood analysis in the mice is negative for megaloblastic anemia, hypersegmented neutrophils, or elevated serum methylmalonic acid. What is another characteristic of the vitamin that these mice are lacking?

An 85-year-old woman is brought to her primary care provider by her son for a checkup. She is feeling well with no significant complaints. Her son is concerned because she has been bruising more easily over the last 2 weeks. Her past medical history is significant for hypertension and hyperlipidemia. She recently had a urinary tract infection that was successfully treated with an extended course of oral cephalexin 3 weeks ago. Family history is noncontributory. Today, her heart rate is 90/min, her respiratory rate is 17/min, her blood pressure is 125/85 mm Hg, and her temperature is 36.7°C (98.1°F). On physical exam, her heart has a regular rate and rhythm, and her lungs are clear to auscultation bilaterally. She has poorly demarcated purple-yellow bruising and areas of dark purple bruising as well. Lab testing reveals a prolonged PT that corrects with mixing studies, normal liver function tests, and a stool test that is guaiac negative. The physician administers an injection that should improve her condition and recommends a follow-up exam and testing. What is the patient deficient in that is replaced by the injection?

A 46-year-old homeless man was found wandering in the supermarket. On examination, an odor of alcohol was noted, he was confused, and appeared to have memory deficits. On exam, he had horizontal nystagmus and an ataxic gait. What is the most likely cause of his clinical presentation?

A 40-year-old man presents to the clinic for a consult. He states that he has been taking very high doses of vitamin E for the last few weeks in order to slow down the aging process because of an article he read on the internet and wants to know if it is safe to continue to do so. Which of the following is a potential complication of ingesting excessively high doses of vitamin E?

A 40-year-old man presents to the clinic with complaints of increased bilateral knee pain. The pain developed over time and now limits his mobility. He states that the pain is worse at the end of the day, though he does have some early-morning stiffness lasting about 20 minutes. He used to have success with over-the-counter NSAIDs, but they no longer help. He has been taking metformin for the past 2 years and is severely obese, with a BMI of 41 kg/m2. Additionally, he reports that he has felt increasingly tired during the day, often dozes off during work, and no longer feels refreshed when he wakes up in the morning. He has a family history of rheumatoid arthritis (RA) on his mother’s side. On physical exam, there is no swelling or tenderness on palpation, but crepitus is felt in both knees. Which of the following is the underlying cause of the patient’s symptoms?

A 5-year-old boy whose family recently immigrated from Africa presents for a well-child visit. The boy appears indifferent, does not make eye contact, and keeps to himself. It is noted that his height and weight are below the 5th percentile. Physical exam reveals a protuberant abdomen and the liver is palpated 3 cm below the right costal margin. There are multiple zones of hyper- or hypo-pigmentation and desquamation of the skin. Pitting edema is noted in the bilateral lower extremities. Which of the following is the most likely cause of this child’s condition?

A 38-year-old nursing home worker presents to the clinic with complaints of fever, loss of appetite, fatigue, and productive cough for the past couple of months. His fever is low-grade and sputum is often blood-tinged. He has lost 6.8 kg (15.0 lb) during this period and complains of profound night sweats. A plain radiograph of the patient’s chest shows consolidation in the apical part of the right lung. Baseline investigations show the following:

The physician suspects that the patient is suffering from a chronic lung infection. Which of the following statements best describes the type of pulmonary lesions seen in this patient?

A 6-year-old boy is rushed to the emergency department after being involved in a motor vehicle accident. He has abrasions on his left knee and left elbow. His wounds are cleaned and a pressure bandage is applied. Typically, neutrophils and macrophages are attracted toward the site of injury by various chemical mediators. Which of the following cells is responsible for the initial cascade by the release of TGF-β and PDGF?

A 28-year-old woman follows up at an outpatient surgery clinic due to abnormal scarring of an incisional wound from an abdominal surgical procedure performed six months ago. She reports a history of wound infection with purulent discharge 1 week after surgery. She also complains of an occasional itching sensation over the scar. There is no history of such scar changes in her family. On examination, the incision site has a dense, raised, healed scar. An image of the lesion is shown. Which of the following statements is true regarding this scar abnormality?

A 40-year-old man is rushed to the emergency department after being involved in a motor vehicle accident. He has lacerations on his right arm and some minor abrasions on his face and lower limbs. The resident on call quickly manages the patient with proper care of his open wounds in the emergency department. The patient is admitted to the surgery unit for the daily care of his wounds. His lacerations begin to heal with proper dressing and debridement. Which of the following best describes the healing process in this patient?

A 10-year-old boy is brought to the pediatrician by his mother for five days of fever, malaise, and new-onset, full-body, pruritic rash. His immunization history is unavailable. His pulse is 110/min, his temperature is 37.8°C (100.0°F), and his respirations are 26/min. On examination of the skin, diffuse peeling vesicular lesions involving the arms and chest are observed. The pediatrician diagnoses the boy with chickenpox and reassures the patient’s mother. A few days later, the boy returns to the clinic for a follow-up. The skin lesions have healed, and scars have formed. The formation of these scars is best described by which of the following statements?

A 20-year-old college student is brought to the emergency department by his friends with complaints of abdominal pain and vomiting twice in the past couple of hours. He describes the pain as 8/10 in intensity and he also complains of nausea. He says that there have been a couple of similar episodes in the past, though none this severe. He has no history of recent travel. The patient reports no smoking history, alcohol consumption, or recreational drug use. Family history is significant for his father being diagnosed with colon cancer at age 44. On physical examination, hyperpigmented macules are noted around the mouth and in the oral cavity. An abdominal exam shows mild tenderness to palpation in the left upper quadrant with no obvious palpable masses. A contrast CT of the abdomen confirmed the presence of intussusception in the small intestine. Which of the following is the mode of inheritance of the genetic condition most likely present in this patient?

A 58-year-old man presents with low back pain that began a couple of weeks ago and has been gradually increasing in severity. Today, he rates the pain intensity as 6/10. There is no radiation or associated paresthesias and no history of trauma. Past medical history is significant for an aggressive squamous cell carcinoma of the right lung with surgical resection followed by adjunct chemotherapy and radiation therapy that he completed 6 months ago. Technetium bone scan reveals metastatic lesions in the lumbar vertebrae at levels L2–L4. The physician explains that these are likely metastatic lesions from his primary lung cancer. What route of spread of these metastatic lesions is most likely?

A group of researchers is investigating oncogenes, specifically the KRAS gene, associated with colon, lung, and pancreatic cancer. They have established that the gain-of-function mutation in this gene increases the chance of cancer development. They are also advancing the research further to study tumor suppressor genes. Which of the following genes is considered a tumor suppressor gene?

An 8-month-old child presents with a history of poor growth and a chronic cough. He was born to a 21-year-old woman at 41 weeks of gestation. Soon after birth, he developed respiratory distress and was admitted to the neonatal intensive care unit, where he received mechanical ventilation for 24 hours. He was initially breastfed, but because of frequent vomiting and loose bowel movements, he was formula-fed after that. Despite this change, he continued to have loose, large, greasy, foul-smelling stools and failure to thrive. On today’s physical examination, his temperature is 37.0°C (98.6°F), his heart rate is 120/min, and his blood pressure is 80/60 mm Hg. Oxygen saturation is 97% on room air, and his weight is 6.7 kg (14.8 lb, < 5th percentile). Physical examination is significant for bilateral otitis media and mild nasal congestion. Normal breath sounds with mild wheezing and rales are heard. What is the pathophysiology behind the patient’s bowel habits?

A 55-year-old woman with diabetes presents to the emergency department due to swelling of her left leg, fever, and chills for the past 2 days. The woman’s maximum recorded temperature at home was 38.3°C (101.0°F). Her left leg is red and swollen from her ankle to the calf, with an ill-defined edge. Her vital signs include blood pressure 120/78 mm Hg, pulse rate 94/min, temperature 38.3°C (101.0°F), and respiratory rate 16/min. On physical examination, her left leg shows marked tenderness and warmth compared with her right leg. The left inguinal lymph node is enlarged to 3 x 3 cm. Which of the following chemical mediators is the most likely cause of the woman’s fever?

A 20-year-old woman presents to the emergency department with painful swelling in the middle of her neck for the past 3 days. She does not have pain with swallowing, difficulty breathing, or voice changes. On examination, a red, 5 x 5 cm, exquisitely tender, non-pulsatile, fluctuant mass is present in the midline on the anterior aspect of the neck. The patient is prepared for an incision and drainage of the neck abscess. What is the mechanism that allows inflammatory cells to enter the tissue space?

A 48-year-old man was treated in the emergency department for a stab wound to his chest. Three months later, he developed a firm 4 x 3 cm (1.6 x 1.2 in) nodular mass with intact epithelium over the site of the chest wound. On local examination, the scar is firm, non-tender, and there is no erythema. The microscopic examination of the excised mass reveals fibroblasts with plentiful collagen. Which of the following processes is most likely related to the series of events mentioned above?

A 67-year-old man presents to the surgical clinic with swelling of his right leg, fever, and chills for 2 days. The maximum recorded temperature was 38.3°C (101.0°F) at home. His right leg is red and swollen from the dorsum of the foot to the thigh with an ill-defined edge. Venous stasis ulcers are present in both of his limbs, but those on the right have a yellow discharge. The vital signs include blood pressure 120/78 mm Hg, heart rate 94/min, temperature 38.3°C (101.0°F), and respiratory rate 16/min. On physical examination, there is tenderness and warmth compared with his left leg. Dorsalis pedis pulses are present on both of the ankles. What is the most likely cause of the right shift of the hemoglobin dissociation curve for his condition?

A 71-year-old man presents to the clinic with complaints of right wrist pain for 2 days. On examination, redness and swelling were noted on the dorsal aspect of his right wrist. He had pain with extreme range of motion of the wrist. His history includes 2 hip replacements, 2 previous episodes of gout in both first metatarsophalangeal joints, and hypertension. Two days later, the swelling had increased in the dorsal aspect of his right wrist and hand. Wrist flexion was limited to 80% with severe pain. The pain was present on palpation of the scaphoid bone. Due to the suspicion of fracture, the patient was referred to his general practitioner for radiographs. These findings were consistent with gouty arthritis. What is the most likely cytokine involved in this process?

A 45-year-old man presents to a surgeon with a painless lump on his right leg. He noticed the lump 6 months ago but did not seek medical care since it didn’t bother him. However, he is more concerned now since the swelling has gotten bigger in the last 3 months. He mentions that his father and brother have lipomas on their extremities, so he wasn’t initially concerned about the lump on his leg. On physical examination, the swelling is well circumscribed and nontender, measuring approximately 4 x 5 cm (1.6 x 2 in). After evaluation, the surgeon performs a surgical resection and sends the tissue for histopathological examination. The pathologist reports the tumor to be a liposarcoma rather than a lipoma. What enzyme is most likely to show increased activity in this patient’s tumor cells?

A 40-year-old man presents to his physician with progressive weight loss for the last 3 months. He also notes that he frequently sweats profusely at night and has a recurring low-grade fever, for which he takes acetaminophen. The patient denies any symptoms such as cough, breathlessness, or gastrointestinal symptoms. His temperature is 37.1°C (98.8°F), his pulse is 76/min, his blood pressure is 116/78 mm Hg, and his respiratory rate is 13/min. On physical examination, he has generalized pallor. Bilateral cervical lymphadenopathy is present. Laboratory evaluation confirms the diagnosis of Hodgkin lymphoma. Which of the following viral infections is most likely to have played a role in the pathogenesis of this patient’s malignancy?

A 28-year-old woman presents to the emergency department because of the sudden onset of left-sided localized chest pain and dyspnea. She has no significant past medical history and takes no medications. Blood pressure is 110/68 mm Hg, pulse is 110/min, respiratory rate is 26/min, and temperature is 37.3℃ (99.1℉). Cardiac auscultation demonstrates no murmurs, rubs, or gallops. Breath sounds are diminished in the left lower posterior chest, which is also dull to percussion. Her right calf is swollen and tender.  A chest X-ray is taken (see picture). Laboratory studies show:

A 70-year-old man presents for his annual check-up. He says he feels well except for occasional abdominal pain. He describes the pain as 4–5 out of 10 in intensity, located in the periumbilical region. The pain occurs 1–2 times a month, and it always subsides on its own. The patient denies any recent history of fever, chills, nausea, vomiting, weight loss, or change in bowel or bladder habits. His past medical history is significant for hypertension, hyperlipidemia, and peripheral vascular disease, managed with lisinopril and simvastatin. The patient has a 40-pack-year smoking history and drinks 1–2 alcoholic beverages per day. His blood pressure is 150/100 mm Hg, and his pulse is 80/min. Peripheral pulses are 2+ bilaterally in all extremities. Abdominal exam reveals a bruit in the epigastric region and mild tenderness to palpation without rebound or guarding. There is also a pulsatile abdominal mass felt on deep palpation in the periumbilical area. The remainder of the physical exam is normal. Laboratory studies show:

A 60-year-old man presents to the clinic for his annual wellness visit. He has occasional leg cramps, and his legs feel heavy, especially after standing for long hours to teach his classes. His past medical history is significant for hypertension which is controlled with metoprolol and lisinopril. He has smoked half a pack of cigarettes daily for the past 30 years. He does not drink alcohol. Family history is significant for myocardial infarction (MI) in his father at age 55. His blood pressure is 130/80 mm Hg, and his pulse rate is 78/min. On physical examination, there are tortuosities of the veins over his lower leg, more pronounced on the left. Peripheral pulses are 2+ on both lower extremities, and there are no skin changes. Strength is 5 out of 5 in all extremities bilaterally. Sensation is intact. The rest of the examination and the laboratory tests are normal. What is the pathophysiology responsible for this patient’s symptoms?

A 23-year-old man has a sudden loss of consciousness while pitching in a baseball game. He has no history of sports-related injuries. He regains consciousness after cardiopulmonary resuscitation. Past medical history is negative for any neurological and cardiovascular problems. Physical examination reveals a prominent A wave on the jugular venous pulse and a double apical impulse. There are no audible murmurs, but an S4 is present. What is the most likely diagnosis?

An 11-year-old child complains of pain in the leg while playing. Blood pressure is 140/90 mm Hg in the upper limb and 110/70 mm Hg in the lower limb. There is a brachial-femoral delay in the pulse. Cardiac auscultation reveals a loud S1 and S2, along with the presence of an S4. A systolic ejection murmur is heard in the interscapular area. Chest X-ray reveals notching of the ribs. Which of the following is the most likely diagnosis?

A 54-year-old woman presents to the emergency department with a chief complaint of chest pain. The pain is described as sharp and located in the anterior part of the chest. There is no radiation of the pain; however, its intensity decreases while sitting and leaning forward. There is no associated shortness of breath. She is afebrile and her vital signs are all normal. The lungs are clear to auscultation, and cardiovascular examination demonstrates scratchy and squeaking sounds at the left sternal border. The ECG shows new widespread ST-segment elevation and PR depression in leads II, III, and aVF. Which of the following is the most likely cause of this patient’s presentation?

A 68-year-old woman presents to the physician for headaches and pain with chewing. She has a history of hypertension that is well controlled with lisinopril. She denies any tobacco use. Her blood pressure is 128/84 mm Hg, her pulse is 86/min, and her respiratory rate is 12/min. Physical exam reveals a tender and prominent left temporal artery. A biopsy of the temporal artery shows granulomatous inflammation. What is a serious complication of this patient’s condition if left untreated?

A 59-year-old man is brought to the emergency department after collapsing on the floor at a grocery store 30 minutes ago. His wife states that he complained of dizziness and chest pain prior to falling down. Medical history is significant for hypertension and diabetes mellitus but his wife says that he does not take his medications regularly. His temperature is 37.0°C (98.6°F), pulse rate is 67/min, respiratory rate is 16/min, and blood pressure is 152/98 mm Hg. Physical examination, including chest auscultation, is within normal limits. He is awake but in distress. The on-call resident who is evaluating him does a 12-lead ECG, which is shown in the exhibit. The initial blood test results are indeterminate and a second set of blood tests are sent to the lab after 4 hours. Which of the following results are most likely to be seen in this patient on the second set of tests?

A 27-year-old man has a pre-employment health evaluation. He has no past or current medical problems, but there is a strong family history of ischemic heart disease on his father’s side. The patient drinks alcohol occasionally but does not use any illicit drugs or smoke. On examination, the physician notices that the patient is very tall with hypermobile joints and long fingers (seen in the image). Auscultation of the heart reveals a mid-systolic click over the apex. What is the most likely mechanism behind this finding?

A 37-year-old man presents to the physician with complaints of breathlessness and fever for the past few days. He says that the shortness of breath is the same throughout the day and not related to exertion. His past medical history is not significant, and he denies any recent sick contacts. He admits that he uses marijuana frequently and illicit intravenous drugs intermittently. His vital signs include: blood pressure 120/60 mm Hg, temperature 38.3°C (101.0°F), respiratory rate 16/min, and pulse 65/min (regular). Physical examination reveals track marks on the arms and a lesion on the patient’s left ring finger, as shown in the picture. An early diastolic murmur is heard over the right second intercostal space; S3 and S4 are also present. Echocardiography shows vegetations on the aortic valve with mild valvular insufficiency. Serial blood cultures are performed, and results are pending. Which of the following is most likely to be responsible for this patient’s condition?

A 9-year-old boy is brought to the office because of exertional dyspnea and fatigability. The patient tires easily when running or playing. His parents say that he was diagnosed with congenital heart disease during infancy, but they refused treatment. They do not remember much about his diagnosis. The patient also had occasional respiratory infections throughout childhood that did not require hospitalization. He takes no medications and has no family history of heart disease. His pulse is 98/min, respirations are 16/min, temperature is 37.2°C (98.9°F), and blood pressure is 110/80 mm Hg. Physical examination shows toe cyanosis and clubbing but no finger abnormalities. Cardiac auscultation reveals a continuous machine-like murmur. All extremity pulses are full and equal. Which of the following is the most likely diagnosis?

A 50-year-old man presents to his primary care physician with a chief complaint of chest pain that is squeezing in nature. He used to have similar symptoms in the past while playing tennis with his friends. Yesterday, while moving furniture in his new home, he experienced this pain that lasted for 15 minutes and radiated towards his jaw and shoulder. He has been diagnosed with diabetes mellitus and hypertension for over 10 years and regularly takes his medications. The pain is not associated with nausea, vomiting, food intake, sweating, or cough. On physical examination, the patient is not in acute distress. The vital signs include blood pressure 135/85 mm Hg, heart rate 80/min, respiratory rate 16/min, temperature 36.9°C (98.5°F), and body mass index (BMI) of 30 kg/m2. On physical examination, bilateral vesicular breath sounds are heard with absent chest tenderness. Cardiovascular examination reveals normal S1 and S2 without any abnormal sounds or murmurs. Abdominal examination is within normal limits. What is the most likely cause of this patient’s condition?

A 24-year-old woman presents to her primary care doctor with complaints of intermittent fever and joint pain for approximately a month. During this time, the patient also reports a loss of appetite and 5 kg (11 lb.) unintentional weight loss. She has no chills, night sweats, or pertinent positive on review of systems and no significant past medical history. She does not take any regular medications. Family history is negative for cancer or hematologic disorders. A complete blood count (CBC) is performed which shows severe pancytopenia. What is the next best step in evaluating this patient?

A 68-year-old man presents to his primary care physician for a routine wellness exam. He currently has no complaints. He has a slightly elevated calcium level (10.7 mg/dL) on lab testing, and some plasma cells are found in his peripheral blood smear (less than 10%). His physician orders a serum protein electrophoresis which demonstrates a slight increase in gamma protein that is light chain predominate. What is the most likely complication of disease progression in this patient if left untreated?

A 52-year-old postmenopausal woman presents to her primary medical clinic with complaints of back pain and increased fatigue for the past 6 months. This past week, the back pain radiates to her legs, is described as stabbing in nature, and is severe (7/10 in intensity). There are no associated paresthesias. She unintentionally lost 4.5 kg (10.0 lb) in the past 6 months. She has not had any injuries or recent falls. Her past medical history is noncontributory, and she does not take any medications. The physical examination is normal. The laboratory studies show:

A peripheral blood smear shows normocytic normochromic cells. An X-ray reveals multiple osteolytic lesions in the vertebrae and long bones. Serum protein electrophoresis shows a monoclonal spike. A bone marrow biopsy shows increased plasma cells making up greater than 50% of the total cell population. What is the most likely diagnosis in this patient?

A 27-year-old man who recently immigrated to the United States with his family is diagnosed with an autosomal dominant disorder that causes anemia by extravascular hemolysis. The doctor explains that his red blood cells (RBCs) are spherical, which decreases their lifespan, and explains that a splenectomy may be required in the future. Which of the following is most likely to be defective in this patient?

A 15-year-old boy with a sore throat, fever, and generalized malaise is admitted to the pediatric floor. On physical exam, he has diffuse white exudate on both tonsils, in addition to a palpable spleen and mild hepatomegaly. Peripheral blood smear shows large and abundant lymphocytes with blue-gray cytoplasm, irregular nuclei, and dark chromatin with inconspicuous nucleoli. Which of the following is the most likely diagnosis?

A 2-year-old boy develops right knee pain and is found to have bleeding in the joint. His birth and delivery were uncomplicated, and his mother had no issues with bleeding during labor. Of note, his maternal grandfather has a history of bleeding complications. Vital signs are within normal limits. Physical exam reveals scattered bruises on his lower extremities. Laboratory studies show:

Which of the following is the most likely diagnosis?

A 6-day-old infant is brought to the emergency department by her parents. They are concerned that she has been lethargic recently and have also noticed that she has easy bruising. Her mother reports that she has been eating less for the past few days. Today, she was difficult to arouse. She normally nurses 4–5 times a day but ate less yesterday and this morning. The girl was born at 39 weeks’ gestation via spontaneous vaginal delivery at home with minimal prenatal or postnatal care. This is her first visit to a physician of any type. The patient’s pulse is 70/min, respirations are irregular, temperature is 35.8°C (96.4°F), and blood pressure is 130/62 mm Hg. Physical examination shows diffuse petechiae and bruising, but without any patterns that are consistent with child abuse. Which of the following is the most likely cause?

A 32-year-old woman presents to the physician because of fatigue and pallor. She says that symptoms started several months ago and have gradually progressed. She reports that she has been exercising regularly and adhering to a vegan diet. She has normal monthly periods. She has no significant past medical history and takes no current medications. She denies any smoking history, alcohol use, or recreational drug use. Her pulse is 100/min, but vital signs are otherwise normal, and the physical exam is unremarkable. A complete blood count (CBC) reveals anemia with a low MCV (mean corpuscular volume), and a peripheral blood smear shows small erythrocytes. Which of the following is the most likely diagnosis?

A 45-year-old woman visits her primary care provider because of easy fatigability, shortness of breath on exertion, and paresthesias in her legs. Her past medical history is significant for hypertension. She takes hydrochlorothiazide, lisinopril, and a multivitamin every day. Her family history is non-contributory. She drinks alcohol almost every day and smokes cigarettes only when she drinks. Today, her vital signs are temperature 37.0°C (98.6°F), heart rate 94/min, respiratory rate 16/min, and blood pressure 130/92 mm Hg. On exam, she has marked pallor and a faint bluish tinge to her lips and distal fingertips. Her heart has a regular rate and rhythm, and her lungs are clear to auscultation bilaterally. Additionally, she has decreased sensation to light touch and decreased vibration sense in both lower legs. Her complete blood count is as follows:

What is the most likely diagnosis for this patient?

A 58-year-old woman presents with a 2-week history of fever, fatigue, generalized weakness, and bleeding gums. Her past medical history is significant for type 2 diabetes mellitus, managed with metformin. Vital signs are within normal limits. On physical examination, she has bilateral cervical lymphadenopathy and hepatosplenomegaly. A complete blood count and peripheral blood smear reveal normocytic anemia and leukocytosis. Bone marrow biopsy is performed, which shows > 20% myeloperoxidase-positive myeloblasts with splinter-shaped structures in the cytosol. The patient is started on a vitamin A derivative. Which of the following chromosomal translocations is most likely responsible for this patient’s condition?

A 25-year-old man is brought by ambulance to the emergency department after a high-speed motor vehicle collision. He has significant traumatic injuries, including a lacerated left arm, and has sustained a massive hemorrhage. Blood transfusion is required immediately. Which of the following ABO blood groups of red blood cells should this patient be transfused with?

A 43-year-old woman presents with left calf pain. She denies any previous episodes of such pain. Her medical history is significant for cervical cancer in the past treated with hysterectomy; she has had no evidence of recurrence of regular follow-up exams. Current medications are an estrogen-containing oral contraceptive and a multivitamin. The patient reports a 20-pack-year smoking history but no alcohol or recreational drug use. The patient is afebrile, and her vital signs are within normal limits. On physical examination, her left calf is swollen, erythematous, and tender to palpation. A D-dimer level is positive. Which of the following is the most likely etiology of this patient’s condition?

A 45-year-old chronic smoker presents to the physician with a complaint of worsening left shoulder pain that has lasted for several months. It has become acutely worse over the past 2 weeks and now radiates down his left arm. Physical examination reveals a palpable 2 x 1.5 cm supraclavicular lymph node along with decreased grip strength in his left hand. Examination of the face reveals partial ptosis of the left eyelid and miosis of the left eye. Laboratory testing shows the following values:

An X-ray of the chest reveals a soft tissue mass at the apex of the left lung with possible involvement of the first rib. What is the most likely diagnosis?

A 56-year-old man presents to the clinic for a checkup with a 1-year history of worsening shortness of breath and weight loss. He is a former construction worker and was employed in a steel mill when he was in high school. He is an active smoker with a 36-pack-year smoking history. His blood pressure is 130/78 mm Hg, pulse rate is 90/min, respiratory rate is 16/min, and BMI is 31 kg/m2. The patient is afebrile, and his oxygen saturation at rest is 95% on room air. Lung examination reveals a mildly prolonged expiratory phase and no wheezing or crackles are noted. A pulmonary function test is recommended for the patient. Two weeks later, he returns with a report that shows an FEV1/FVC ratio of 60% and FEV1 of 50% of the predicted value. The lung volumes show a total lung capacity of 110% of the predicted value, a residual volume of 115% of the predicted value, and a DLCO of 60% of the predicted value. Which of the following is the most likely diagnosis?

A 30-year-old man presents to the emergency room for left-sided chest pain, shortness of breath, and cough with purulent sputum. One week ago he was diagnosed with influenza. Pulse is 100/min, respiratory rate is 26/min, temperature is 38.7°C (101.7°F), and blood pressure is 120/60 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 92%. His complete blood count (CBC) and chest X-ray findings are as follows:

What is the most likely diagnosis?

A newborn delivered at 33 weeks of gestation has a respiratory rate of 70/min and a heart rate of 148/min now at two hours after birth. He is grunting and has intercostal and subcostal retractions. He also has peripheral cyanosis. An immediate chest radiograph is taken which shows fine reticular granulation on both lungs. Which of the following is the most likely diagnosis?

A 45-year-old man presents to an urgent care clinic because he coughed up blood this morning. Although he has had a persistent cough for 3 weeks, he had never coughed up blood until now. His voice is hoarse and he admits that it has been like that for the past few months. Both his past medical history and family history are non-significant. He has smoked a pack of cigarettes a day since the age of 20 and drinks a glass of wine every evening. His vitals include: pulse rate 78/min, respiratory rate 14/min, temperature 36.5°C (97.8°F), and blood pressure 140/88 mm Hg. An indirect laryngoscopy reveals a rough vegetating lesion on the free border of the right vocal cord. Which of the following is the most likely diagnosis?

A 14-year-old boy is brought to the office by his mother with the complaint of worsening nasal congestion for the past 5 months. He also complains of continuous bilateral nasal discharge. He adds that he no longer has any sense of smell. His medical history is significant for delayed growth and recurrent bronchitis since he was 6 years old. Anterior rhinoscopy reveals multiple semi-transparent, soft, and mobile masses in the middle meatus. Which of the following is the most likely etiology of this patient’s condition?

A 32-year-old man comes to the emergency room because of severe breathlessness for the past few hours. Over the past few years, he has been treated for asthma by several physicians, but his symptoms have continued to get worse. He has never smoked. Both his father and his uncle (father’s brother) died from chronic lung disease in their early 40’s. His respiratory rate is 20/min, and his temperature is 37.0°C (98.6°F). On physical examination, he has prolonged expiration, clubbing, and bilateral crackles. Hepatomegaly is noted. What is the most likely diagnosis?

A 28-year-old man presents to his general practitioner for a regular checkup. He has had trouble breathing lately with coughing, shortness of breath, and wheezing. The problems started when he went running outdoors, but he has recently had symptoms when taking a light walk or resting. As a child, he suffered from atopic dermatitis, just like his father and sister. He has a history of hay fever. Currently, his vital signs are within normal limits. What is the most likely cause of his symptoms?

A baby is born at 32 weeks of gestation by spontaneous vaginal delivery. The mother had gestational diabetes; however, she had no other pregnancy-related diseases and was otherwise healthy. The baby’s blood pressure is 100/58 mm Hg, heart rate is 104/min, and oxygen saturation is 88%. He has tachypnea, subcostal and intercostal retractions, nasal flaring, and cyanosis responding well to oxygen treatment. A nasogastric tube was positioned without problems. Which of the following is the most likely diagnosis?

A 65-year-old woman schedules an appointment with her physician because of weight loss and weakness over the past 5 months that is getting progressively worse. The weakness is more noticeable when climbing stairs and combing her hair, but it improves after brief exercise or repetitive movement. She also has experienced bladder incontinence for the past 4 weeks and was given an anticholinesterase agent with no improvement. She has no other significant past medical history except smoking a pack of cigarettes daily since age 17. Her vital signs are within normal limits. Physical examination reveals moderate symmetric weakness of the upper and lower extremities. What is the most likely cause of her symptoms?

A 66-year-old man presents with severe respiratory distress. He was diagnosed with pulmonary hypertension secondary to occupational pneumoconiosis. Biopsy findings of the lung show ferruginous bodies. What is the most likely etiology in this patient?

A tall, slender 32-year-old man presents to the emergency room because of sudden chest pain, cough, and shortness of breath. He denies any medical problems and takes no medications. He notes that both parents are healthy, but his father is also very tall and slender. On physical examination, he has decreased breath sounds on the right. Percussion reveals increased resonance. Chest radiography shows a white visceral pleural line on the right side of his chest. His pCO2 is elevated, and pO2 is decreased. What is the most likely cause of his symptoms?

A 69-year-old woman is brought by her husband to the emergency department because of the sudden onset of chest pain and shortness of breath that started 2 hours ago. The pain increases with deep inspiration. The patient had a total hip replacement 20 days ago. She has hypertension, for which she takes a calcium channel blocker. She has smoked 1 pack of cigarettes daily since age 18. Her blood pressure is 100/60 mm Hg, pulse rate is 82/min, and respiratory rate is 30/min. She is visibly tachypneic. Examination of the chest reveals dullness to percussion at the right lung base. A computed tomography (CT) scan of the chest shows a focal, wedged-shaped, pleura-based triangular area of hemorrhage in the right lower lobe of the lung. What is the most likely cause of this patient’s pulmonary lesion?

A 10-year-old boy presents to the clinic with complaints of a cough productive of yellow sputum. This cough has lasted two weeks and is the 4th episode the boy has had this year. He has had recurrent episodes of cough since childhood; previous episodes have subsided with antibiotics. There is no family history of respiratory disorders. The boy’s vaccinations are up to date. The heart rate is 98/min, the respiratory rate is 13/min, the temperature is 37.6 °C (99.7 °F), and the blood pressure is 102/70 mm Hg. Auscultation reveals the cardiac sounds heard more on the right side of the chest. Chest X-ray shows that the cardiac apex is on the right. CT scan results suggest bronchiectasis. Which of the following structures are most likely impaired in this patient?

A 47-year-old man with alcoholism presents to the office for a 72-hour history of intense right-sided chest pain. He also reports a 2-week history of fever, chills, diaphoresis, and persistent coughing with abundant malodorous sputum. Chest radiography shows a round consolidation with air-water levels in the middle third of the right lung. A sputum sample is sent for analysis, and the results are pending. Which of the following is the most likely diagnosis?

A 60-year-old man, who was a coal miner for more than 15 years, presents with a cough for the past 6 years and new shortness of breath for the past 4 months. His cough is dry and persistent, and his dyspnea is exacerbated by physical activity. He admits that he did not take any safety measures when working in the mines. Vital signs include: heart rate 85/min, respiratory rate 32/min, and blood pressure 125/90 mm Hg. Physical exam reveals diminished breath sounds on both sides. Chest X-ray shows interstitial fibrosis with reticulonodular infiltrates bilaterally. Which of the following is the most likely diagnosis?

A 45-year-old woman presents to the office with a chief complaint of a persistent cough for 6 weeks. She also has night sweats and has lost 5 kg (11 lb) in the last 2 months. She recently returned from a 6-month trip to Peru. Her vitals include: heart rate 82/min, respiratory rate 17/min, temperature 38.0°C (100.4°F), and blood pressure 107/80 mm Hg. On auscultation, she has diminished respiratory sounds at the base of the right lung. Chest radiography shows an opacity in the right apex. What is the most likely cause of her presentation?

A 65-year-old woman presents to the ER with shortness of breath, cough, and severe lower limb enlargement. The dyspnea began suddenly a week ago and gets worse with exercise but does not disappear with rest. Her cough is dry, persistent, and non-productive. She has a family history of maternal hypertension. Her heart rate is 106/min, respiratory rate is 28/min, and blood pressure is 140/90 mm Hg. On physical examination, thoracic expansion is diminished on the right side with rhonchi and crackles on the lower two-thirds of both sides, with left predominance. A systolic murmur is heard over the tricuspid foci, which increases in intensity with inspiration. There is jugular engorgement when the bed is placed at 45°. Palpation of the abdomen is painful on the right hypochondrium, with hepatomegaly 4 cm below the lower coastal edge. Hepatojugular reflux is also present. Soft, painless, pitting edema is present in both lower limbs up to the middle third of both legs. Lung computed tomography (CT) and transthoracic echocardiogram are performed and detect pulmonary fibrosis and right heart failure. What is the most likely diagnosis?

A 5-year-old immigrant girl presents to the office with her mother because she has had a fever and cough for the past month. They moved from Africa to the United States about eight months ago. She denies any sore throat, rhinorrhea, diarrhea,
or changes in appetite. However, since her well-child visit six months ago, she has lost weight, falling from the 36th percentile to the 19th percentile. Her pulse is 75/min, respirations are 15/min, temperature is 38.2°C (100.7°F), and blood pressure is 110/76 mm Hg. Physical exam reveals non-tender bilateral cervical lymphadenopathy. She is breathing normally, but breath sounds are diminished over the right hemithorax. There is no rhinorrhea and the posterior oropharynx is clear. After a chest X-ray is ordered, which of the following is the most appropriate next step in management?

A 2-month-old girl with a history of DiGeorge syndrome presents to the emergency department following a seizure. Her mother states that she had been inconsolable all day and refused to feed. She was born at 39 weeks’ gestation via spontaneous vaginal delivery. She is up to date on all vaccinations. Her pulse is 120/min, respirations are 40/min, and temperature is 37.0°C (98.6°F). On examination, she is somnolent, and her fontanelles are open and soft. While attempting to take her blood pressure, the patient’s arm and hand flex sharply and do not relax until the cuff is released. A light tap on the cheek results in an atypical facial muscle twitch. Laboratory studies are pending. Which of the following is the most likely cause of her symptoms?

A 65-year-old man presents to his physician complaining of a painful rash that developed over the last week. He does not have any other complaints. His past medical history is significant for occasional heartburn. His blood pressure is 132/86 mm Hg, heart rate is 84/min, and respiratory rate is 15/min. Physical examination reveals a rash on the right side of his chest. The rash does not appear to cross the patient’s midline. A picture of the skin lesion is shown below. Which of the following best describes this rash?

A 35-year-old woman who was recently ill with an upper respiratory infection presents to the emergency department with weakness in her lower limbs and difficulty breathing. Her symptoms began with a burning sensation in her toes along with numbness. She states that the weakness has been getting worse over the last few days and now involves her arms and face. Currently, she is unable to get up from a chair without assistance. Temperature is 37.0°C (98.6°F), blood pressure is 145/89 mm Hg, pulse is 99/min, and respiratory rate is 12/min. Pulse oximetry on room air shows an oxygen saturation of 95%. On physical examination, she has diminished breath sounds on auscultation of the bilateral lung fields with noticeably poor inspiratory effort. A neurological exam reveals 3/5 strength and diminished deep tendon reflexes of the bilateral lower extremities. What is the most likely diagnosis?

A 6-month-old girl is being evaluated at a pediatrician’s office for poor growth and to establish care. Her family has recently immigrated from an underdeveloped country. She sleeps a lot with poor appetite and constipation. She was born at 39 weeks’ gestation via spontaneous vaginal delivery. At the physician’s office, her blood pressure is 80/40 mm Hg, pulse is 95/min, respirations are 18/min, and temperature is 35.2°C (95.5°F). Physical examination reveals a puffy face with a dull expression and a large tongue. Her conjunctivae are pale. She does not have a social smile or head control. Abdominal examination shows an umbilical hernia. Testing of which of the following will most likely be abnormal?

A 28-year-old man is brought to the emergency room in a barely conscious state. He was feeling drowsy and fell to the floor several hours ago. His colleague who accompanied him says he has had similar episodes 5 times in the past 3 months. He has no significant medical history and takes no medications. His blood pressure is 110/80 mm Hg, pulse is 114/min, and capillary blood glucose is 15 mg/dL. Immediate intravenous (IV) dextrose with thiamine is started, and the patient rapidly regains consciousness. A contrast computed tomography (CT) scan of the abdomen is performed, which reveals a tumor in the pancreas. Which of the following relative laboratory findings would you most likely expect to find in this patient?

A 36-year-old woman presents to the physician with a recent onset of generalized weakness and weight gain. Physical examination reveals diffuse nontender enlargement of the thyroid gland. Fine-needle aspiration and cytology show lymphocytic infiltration with germinal centers and epithelial Hürthle cells. Which of the following autoantibodies is most likely to be found in this patient?

A 34-year-old woman presents to her family physician with concerns about constant fatigue and difficulty with breastfeeding. She delivered her first child 2 weeks ago and required treatment in the intensive care unit for severe postpartum hemorrhage. She has tried multiple pumps and self-stimulation techniques to promote breast milk production, but none of these strategies has worked. Her blood pressure is 88/56 mm Hg, and her pulse is 120/min. What is the most likely cause of her symptoms?

A 42-year-old man who is employed as a construction worker presents to his primary care physician with complaints of moderate headaches and profuse sweating. He reports the need to carry up to 3 additional shirts to work because they are quickly drenched, even with tasks of low physical exertion. His coworkers have commented about his changing glove and boot sizes, which have increased at least 4 times since he joined the company 10 years ago. His blood pressure is 160/95 mm Hg. Physical exam reveals hyperhidrosis, noticeably large skin pores, hypertrichosis, widely spaced teeth, and prognathism. Which of the following best explains the patient’s clinical manifestations?

A 28-year-old woman presents to the clinic with palpitations, tremors, heat intolerance, insomnia, and loose bowel movements for the past 2 months. She has lost 8 kg (17.6 lb). Her vital signs are temperature is 37.8°C (100.0°F), heart rate is 120/min, and blood pressure is 130/80 mm Hg. Physical examination also reveals a moderately-sized diffuse goiter with a bruit heard over it. She is agitated and has a fine tremor with warm moist palms; she also had increased deep tendon reflexes. Exophthalmos is noted. The laboratory results are:

The complete blood count is normal. A thyroid scan demonstrates diffusely increased uptake. A high level of thyroid-stimulating immunoglobulin antibodies is detected. What diagnosis explains these findings?

А 42-уеаr-old woman рrеѕеntѕ wіth fасіаl аѕуmmеtrу. Yesterday, she noticed that her face appeared to be dеvіаted to the rіght. Ѕhе dеnіеѕ аnу trаumа or rесеnt trаvеl. Неr раѕt mеdісаl hіѕtorу іѕ nonсontrіbutorу. Vital signs include: blood pressure 110/78 mm Hg, temperature 36.5°C (97.8°F), pulse 78/min, and respiratory rate 11/min. Оn рhуѕісаl ехаmіnаtіon, thеrе іѕ drooріng of thе left ѕіdе of thе fасе, thе left nаѕolаbіаl fold іѕ аbѕеnt, аnd ѕhе іѕ unаblе to сloѕе hеr left еуе or wrinkle thе left ѕіdе of hеr forеhеаd. Whеn the patient is аѕkеd to ѕmіlе, thе result is shown in the photograph. The remainder of the nеurologіс ехаm іѕ normаl. No lesions are seen on the skin, mucous membranes, or ear canal. A non-contrast computed tomography (CT) scan of the head is unremarkable. Which of the following is the most likely cause of her symptoms?

A 13-year-old girl presents after losing consciousness during class 30 minutes ago. According to her friends, she was doing well this morning, and they did not notice anything abnormal. The patient’s mother says that her daughter does not have any medical conditions but recently developed increased urinary frequency and lost weight despite a regular diet. Her blood pressure is 100/78 mm Hg, pulse is 89/min, and temperatureis 37.2°C (99.0°F). Her breathing is rapid but shallow. Fingerstick glucose is 300 mg/dL. Blood is drawn for additional laboratory tests, and she is started on intravenous insulin, normal saline, and electrolyte replacement. Which of the following human leukocyte antigen (HLA) subtypes is associated with this patient’s most likely diagnosis?

A 28-year-old woman presents with facial flushing, weakness, and diarrhea for the past month. She denies any history of smoking, alcohol use, or recreational drug use. She went on a trip to Thailand 2 years ago with her family but denies any recent travel. Her vital signs are temperature 37.2°C (99.0°F), heart rate 78/min, respiratory rate 16/min, and blood pressure 120/88 mm Hg. Laboratory findings are significant for a potassium level of 3.3 mmol/L and serum calcium of 11.0 mg/dL. Genetic analysis reveals a mutation in the menin 1 gene on chromosome 11. Which of the following is the most likely diagnosis?

A 27-year-old woman presents to the emergency department for loss of consciousness while at work. Her colleagues say that she had been complaining of a headache all day. Her past medical history is significant for diabetes mellitus type 1. Blood pressure is 70/60 mm Hg, pulse is 105/min, temperature is 37.2°C (99.0°F), and respiratory rate is 28/min and shallow. Physical exam reveals black eschar formation on her nose and her breath has a fruity odor. She is poorly responsive, but her pupils are equal and there are no focal neurological signs. Laboratory findings are significant for serum glucose of 750 mg/dL, potassium of 3.3 mmol/L, and blood pH of 7.1. Which of the following diabetic complications is most likely the cause of this woman’s presenting symptoms?

A 27-year-old man who was involved in a motor vehicle collision is brought into the emergency room with a fractured skull. The paramedics report that the patient was conscious and lucid on the way to the hospital, but is now unresponsive. Vital signs include: blood pressure 122/78 mm Hg, temperature 37.0°C (98.6°F), pulse rate 88/min, and respiratory rate 14/min. A noncontrast CT scan of the head shows an epidural hematoma. Which of the following structures is involved in the development of an epidural hematoma?

A 56-year-old man presents with anxiety and fatigue for the past 4 months. He has also had some weight loss and occasional double vision, and a gritty sensation in his eyes for the last 2 months, which are worse at the end of the day. He has also noticed some painless swelling in his fingers and lower legs during the same time period. The patient denies any recent history of fevers, chills, night sweats, nausea, or vomiting. Current medications include aspirin, simvastatin, and omeprazole. Which of the following mechanisms is most likely responsible for this patient’s condition?

А 43-уеаr-old mаn рrеѕеntѕ wіth tіnglіng аnd numbnеѕѕ of the lowеr lіmbѕ for 2 wееkѕ. Не also сomрlаіnѕ of реrѕіѕtеnt раіn in his legs whісh is not relieved by over-the-counter analgesics. His past medical history is significant for type 2 dіаbеtes Mellitus for 2 уеаrѕ, inconsistently managed with mеtformіn аnd glіmеріrіdе. Оn physical ехаmіnаtіon, thеrе іѕ dесrеаѕеd ѕеnѕаtіon to pain in both lower lіmbs, but the deep tеndon rеflехеѕ аrе іntасt. Ніѕ vіtаl ѕіgnѕ include: blood рrеѕѕurе 122/84 mm Нg, tеmреrаturе 36.7°C (98.1°F), and rеѕріrаtorу rаtе 10/mіn. His ankle-brachial pressure index (ABPI) on the right side is 1.1. His blood sugar analyses are as follows:

Which of the following is the best measure for preventing the progression of the symptoms present in this patient?

A 49-year-old woman presents to the office because of tremors for 2 months. She says that her hands have been shaking a lot, especially when she feels stressed. She has also been sweating more than usual and lost 8 kg (17.6 lb) in the last 2 months. She has a past medical history of vitiligo. Vital signs include: heart rate 98/min, respiratory rate 14/min, temperature 37.6°C (99.7°F), and blood pressure 115/75 mm Hg. Physical examination reveals a fine, bilateral hand tremor, and diffuse goiter. Which of the following hormonal imbalances is most likely present?

A 29-year-old woman presents with progressive vision loss in her right eye and periorbital pain for 5 days. She says that she has also noticed weakness, numbness, and tingling in her left leg. Her vital signs are within normal limits. Neurological examination shows gait imbalance, positive Babinski reflexes, bilateral spasticity, and exaggerated deep tendon reflexes in both lower extremities. MRI is obtained and is shown in the image. What is the most likely cause of this patient’s condition?

A 65-year-old woman presents to the clinic for a routine checkup. She has unintentionally lost 4.5 kg (9.9 lb) in the past month, but denies any other symptoms. Her pulse is 90/min, respiratory rate is 18/min, temperature is 37.0°C (98.6°F), and blood pressure is 150/70 mm Hg. An irregularly irregular rhythm is heard on auscultation of the heart. Neck examination reveals a markedly enlarged thyroid with no lymphadenopathy or bruit. Laboratory tests show a low serum thyroid-stimulating hormone level, high T4 level, absent thyroid-stimulating immunoglobulin, and absent anti-thyroid peroxidase antibody. Nuclear scintigraphy demonstrates patchy uptake in the thyroid with multiple hot and cold areas. Which of the following is the most likely diagnosis?

A 13-year-old girl presents with a 4-week history of unrelenting cough, night sweats, and fever. She has no known past medical history and no current medications. The patient recently immigrated to the US from a rural town in northern India. Vaccination status is unknown. Vital signs include: temperature 38.5°C (101.3°F), pulse 115/min, blood pressure 95/65 mm Hg, and respiratory rate 22/min. Physical exam is significant for decreased breath sounds in the right upper lobe and right cervical lymphadenopathy. A chest radiograph reveals multiple cavitations in the right upper lobe and right hilar lymphadenopathy. A sputum culture shows acid-fast bacilli. In addition to the recommended antibiotic therapy for this infection, which of the following compounds should be prescribed?

A 35-year-old woman presents with an unsteady and broad-based gait, dysmetria, and intention tremor in the distal upper extremities. Her medical history is relevant for depression, personality changes, and declining work performance. She has been put on leave from her current job as an elementary school teacher. On physical examination, the patient has dysarthria, dystonia, and an ataxic gait. Ophthalmologic examination reveals multicolored irises with concentric rings around the periphery (findings shown in the photo). Her neurologic exam shows normal motor function with sensation intact. What substance is most likely to have abnormally accumulated in this patient’s tissues?

An 80-year-old woman is brought to the physician by her two daughters for worsening memory loss. They report that their mother has become increasingly forgetful about recent conversations and events. She is unable to remember her appointments and commitments. Three years ago, the patient was moved into a memory care facility because she often got lost on her way home and kept forgetting to take her medications. The patient reports that she is very socially active at her new home and has long conversations with the other residents about her adventures as a flight attendant during her younger years. Which of the following cerebral pathologies is most likely present in this patient?

A 25-year-old man presents to the office for a 3-day history of fever, nausea, and poor appetite. He has also had abdominal pain, joint pain, and fever during this time. He gives a history of regular unprotected sexual relations with multiple partners. He is a non-smoker and drinks alcohol only occasionally. His temperature is 38.0°C (100.4°F), heart rate is 102/min, respiratory rate is 18/min,  and blood pressure is 120/80 mm Hg. On physical examination, his sclerae are icteric and he has hepatosplenomegaly. His abdomen is slightly tender in the right upper quadrant. Serologic markers show the following:

What is the most likely diagnosis?

A 67-year-old man presents with fatigue, progressive abdominal distention, and yellow skin coloration for 2 weeks. He denies fever, chills, or other symptoms. His past medical history is unremarkable. He reports heavy alcohol consumption for several years but says he recently quit. On physical examination, the patient appears jaundiced and is ill-appearing. The sclerae are icteric. Bilateral gynecomastia is present. There is shifting dullness on abdominal percussion with a positive fluid wave. Laboratory findings are significant for the following:

Which of the following is the most likely diagnosis in this patient?

A 40-year-old woman presents with abdominal pain and yellow skin discoloration for the past 4 days. She says that her symptoms started gradually and progressively worsened. Her past medical history is unremarkable. She has been taking oral contraceptive pills for 4 years. Her vitals are temperature 37.5°C (99.5°F), heart rate 102/min, respiratory rate 14/min, and blood pressure 116/76 mm Hg. Physical examination reveals abdominal tenderness, hepatomegaly 4 cm (1.6 in) below the right costal margin, and shifting dullness with a positive fluid wave. A hepatitis viral lab panel for hepatitis, A, B, C, and D is all negative. Abdominal ultrasound reveals evidence of hepatic vein thrombosis. A liver biopsy shows congestion and necrosis in the central zones. Which of the following is the most likely diagnosis in this patient?

A 45-year-old woman presents to the office with a 2-week history of painless rectal bleeding every day with bowel movements. Apart from this, she does not have any other complaints. Her past medical history is significant for 5 normal vaginal deliveries. Her temperature is 36.7°C (98.1°F), heart rate is 72/min, respiratory rate is 14/min, and blood pressure is 115/85 mm Hg. On rectovaginal examination, there is a palpable, nontender, prolapsed mass that can be pushed back by the examiner’s finger into the anal sphincter. What is the most likely diagnosis?

A 46-year-old woman presents for a pre-employment health assessment. She has no complaints. Her last routine wellness examination 8 months ago was normal. She has no significant past medical history and takes no regular medications. She is a nonsmoker and says she quit all alcohol consumption last year. She has never traveled outside the US. A complete hepatic biochemistry panel is performed, which is significant for a serum alkaline phosphatase (ALP) level 5 times the upper limit of the normal range. Immunologic tests are positive for antimitochondrial antibodies. A liver biopsy is performed and reveals an inflammatory infiltrate surrounding the biliary ducts. What is the most likely diagnosis in this patient?

A 25-year-old man who works in construction presents to his primary care physician with a complaint of yellowish discoloration of his skin and eyes for the past 2 weeks. He also complains of nausea and loss of appetite for the same duration. He has no significant medical history. The patient usually smokes cigarettes regularly, but he recently has developed a distaste for smoking. His temperature is 36.5°C (97.7°F), his blood pressure is 111/74 mm Hg, his pulse rate is 83/min, and his respiratory rate is 12/min. On physical examination, there is mild hepatomegaly. Laboratory studies show:

What is the most common mode of transmission for this patient’s diagnosis?

A 4-month-old girl is brought to the office by her parents because they noticed a mass protruding from her rectum while she had a bowel movement during a diaper change. This occurred about 24 hours ago. Shortly afterward, she had 3 episodes of emesis with greenish emesis. She has a past medical history of failure to pass meconium for 2 days after birth, but her newborn screening was otherwise normal. Her vital signs include: heart rate 190/min, respiratory rate 44/min, temperature 37.2°C (99.0°F), and blood pressure 80/50 mm Hg. On physical examination, the abdomen is distended. Examination of the anus reveals extrusion of the rectal mucosa through the external anal sphincter, and digital rectal examination produces an explosive expulsion of gas and stool. The abdominal radiograph shows bowel distention and the absence of distal gas. What is the most likely cause of this condition?

A 25-year-old man presents to the office because of extreme fatigue for the past 2 days. He is also worried about his skin looking yellow. He does not have any other complaints and denies fever or headache. He admits to using intravenous drugs in the past. He does not have any immunization records because he moved from Africa to the US at the age of 18. His vital signs are temperature 37.9°C (100.2°F), heart rate 72/min, respiratory rate 14/min, and blood pressure 100/74 mm Hg. Physical examination is significant mild diffuse abdominal tenderness. His blood tests show an alanine aminotransferase level (ALT) of 2,000 IU/L. A viral hepatitis  panel is ordered which shows:

What is the most likely diagnosis?

A 54-year-old man with worsening refractory epigastric pain secondary to long-standing gastroesophageal reflux disease (GERD) presents for endoscopic evaluation. His medical history is significant for type 2 diabetes mellitus, diagnosed 3 years ago. Current medications are metformin and omeprazole. Which of the following best describes this patient’s most likely endoscopic findings?

A 5-year-old boy with Down syndrome presents to the doctor’s office with his mother. The patient’s mother says that he is not playing or eating as much as he used to and seems lethargic. Expected developmental delays associated with Down syndrome are present and stable. Physical examination reveals dry mucous membranes and abdominal distention with no tenderness to palpation. An abdominal radiograph found in his chart from shortly after birth is shown. Which of the following is the most likely diagnosis in this patient?

It is the first day of your pathology rotation and the attending pathologist gives you a biopsy specimen to examine. She says it is from the antrum of the stomach of a 32-year-old man who has been complaining of abdominal pain for the past 6 months. The patient states the pain gets worse when he is eating. On endoscopy, there was a single ulcerated lesion with a ‘punched out’ appearance. Which of the following is most likely to be seen in this biopsy specimen?

A 60-year-old man presents to your office because he noticed a “weird patch” on the floor of his mouth. He states that he noticed it a few months ago but did not report it because it did not hurt. However, he is concerned because it has not regressed, and its shape has changed. He chews tobacco daily. On examination, you notice the patient has poor dentition. The patch on the floor of his mouth is red with irregular borders. What is the most appropriate way to counsel this patient on his current condition?

A 25-year-old man presents to the emergency department after numerous episodes of vomiting. The patient states that he thinks he “ate something bad” and has been vomiting for the past 48 hours. Today there was blood in the emesis, and he is concerned. He is hypotensive with a blood pressure of 90/55 mm Hg and a pulse of 120/min. IV fluids were started. Physical examination is normal except for mild epigastric tenderness. An immediate endoscopy is performed, and a tear involving the mucosa and submucosa of the gastroesophageal junction is visualized. What is the most likely cause of his hematemesis?

A 70-year-old man presents to the emergency department after several episodes of bloody stools that started six hours ago. He denies nausea, vomiting, or diarrhea and states he has no abdominal pain. On physical exam, he appears pale and the abdomen is nontender to palpation. Pulse is 120/min and blood pressure is 80/60 mm Hg. A stool sample demonstrates bright red blood. Which of the following is the most likely location of his bleeding?

A 42-year-old man presents to his primary care physician complaining of right-sided facial swelling that has progressively worsened over the last month. He has difficulty chewing food but no associated pain. He is up to date on all recommended immunizations. His temperature is 37.2°C (98.9°F), blood pressure is 115/80 mm Hg, and heart rate is 65/min. Physical exam reveals an obvious asymmetry of facial features with edema on the right, but no erythema or lymphadenopathy. There are no focal neurologic deficits. Which of the following is the most likely cause of this patient’s symptoms?

A 5-week-old boy is brought to the emergency department by his mother due to severe vomiting and lethargy for the past 3 days. His mother describes the vomiting as forceful and projectile and says that it contains undigested breast milk but that she did not notice any green fluid. He does not seem to have gained any weight in the past 3 weeks. He has a pulse rate of 144/min, a temperature of 37.5°C (99.5°F), and a respiratory rate of 18/min. Mucous membranes are dry, and the infant is lethargic. Blood chemistries show normal serum sodium and potassium. Abdominal examination reveals a small, palpable mass in the epigastrium that becomes more prominent after vomiting. An ultrasound is ordered. What is the most likely diagnosis causing this patient’s vomiting?

A 41-year-old G3P3 woman presented with acute-on-chronic right upper quadrant abdominal pain. Her last episode of symptoms started about 8 hours before being seen and began after eating a large meal. Her pain was severe, sharp, cramping in character, and localized to the right upper quadrant. She had associated nausea. The patient had experienced similar less severe episodes intermittently over the past 2 years, usually precipitated by the intake of fatty foods. There was no history of fever or jaundice. Vital signs were normal and physical examination was unremarkable. Laboratory findings showed normal liver function tests, serum bilirubin, and serum amylase levels. Ultrasonography of the abdomen revealed multiple stones in the gallbladder. The patient underwent elective cholecystectomy, and her stones are shown in the image. Which of the following best describes these gallstones?

A 42-year-old man presents with acute-onset jaundice. His medical history is significant for chronic obstructive pulmonary disease diagnosed 4 years ago, which is being managed medically, and hospitalization for acute pancreatitis 6 months ago. The patient denies any history of smoking, alcohol, or recreational drug use. His vital signs are within normal limits. His physical examination is significant for jaundice, scleral icterus, wheezing on expiration, and normal heart sounds. Which of the following is the most likely etiology of the liver damage in this patient?

A 10-month-old infant is brought in by his parents because he is vomiting and not passing stool. His parents say he has vomited multiple times over the past couple of hours, but the most recent vomit was green. The patient has no significant past medical history. On physical examination, the patient is irritable and crying. On palpation in the periumbilical region, an abdominal mass is present. Emergency laparotomy is performed, which shows a part of the patient’s intestine folded into the section adjacent to it. Which of the following is the most likely diagnosis for this patient?

A 13-year-old boy is brought to the pediatrician by his parents, as they are concerned about his short stature. He has also had recurrent episodes of diarrhea. His past medical history is significant for iron deficiency anemia diagnosed six months ago. Physical examination is unremarkable, but he is in the 9th percentile for height. Serum anti-tissue transglutaminase (anti-tTG) antibodies are positive. An upper endoscopy, along with small bowel luminal biopsy, is performed. Which of the following histopathologic changes would most likely be present in the duodenal mucosa of this patient?

A 35-year-old woman presents with abdominal pain and fullness plus irregular bowel movements for the past month. She denies any recent change in diet or rectal bleeding. She has no allergies, takes no medications, and has no significant family medical history. She has not traveled recently. A fecal occult blood test is negative. A colonoscopy with biopsies was all normal. Which of the following is the most likely pathophysiology of this patient’s condition?

A 25-year-old woman presents with a slight yellow discoloration of her skin and eyes for the past 2 days. She says she has previously had multiple episodes with similar symptoms. She denies any recent history of nausea, fatigue, fever, or change in bowel and bladder habits. She has no significant past medical history. The patient is afebrile, and her vital signs are within normal limits. On physical examination, her sclerae are icteric and she has mild jaundice. Laboratory findings are significant only for mild unconjugated hyperbilirubinemia. The remainder of her laboratory results are unremarkable. What is the most likely diagnosis in this patient?

A 32-year-old woman presents to her family physician with a long history of depression, irritability, and, more recently, personality changes. Her partner says she has stopped engaging in activities she used to enjoy, such as dancing, drumming lessons, and yoga. The patient denies changes in skin pigmentation and says she keeps a balanced diet low in fat and carbohydrates. Physical exam reveals jaundice and dark rings encircling the irises of both eyes, as well as hepatomegaly and gait disturbances. At a follow-up visit, the patient brings a battery of laboratory tests, including a complete blood count that shows normocytic normochromic anemia, a negative Coombs, normal iron levels, normal fasting glucose levels, elevated aminotransferases and bilirubin, and decreased serum ceruloplasmin levels. Antinuclear antibodies are negative. What is the most likely diagnosis?

A 41-year-old woman presents with pain in her abdomen for the last 3 hours. She says pain is intense, dull, constant, and localized to the right upper quadrant. The pain started about 30 minutes after she had a high-fat meal this morning and is accompanied by nausea. She has had similar episodes in the past after a fatty meal, but they were less severe and resolved after an hour. Her past medical history is otherwise noncontributory. Her temperature is 37.6°C (99.6°F), heart rate is 85/min, respiratory rate is 16/min, and blood pressure is 120/80 mm Hg. Physical examination is within normal limits. An abdominal ultrasound is pending. Which of the following hormones is the likeliest cause of the postprandial aggravation of this patient’s symptoms?

A 38-year-old man arrives at the emergency department with severe periumbilical, colicky pain, and abdominal distention for the past 2 days. He is nauseated and reports light-green emesis 8 times since yesterday morning. He has not had a bowel movement or passed any flatus for 3 days. Past medical history includes a ventral hernia repair 5 years ago. His heart rate is 110/min, respiratory rate is 24/min, temperature is 38.0°C (100.4°F), and blood pressure is 120/90 mm Hg. The abdomen is distended and mildly tender to deep palpation. Bowel sounds are high-pitched and tinkling. Which of the following is the most likely diagnosis?

A 27-year-old woman visits her family physician with a 1-week history of an unpleasant fishy vaginal odor. She was recently treated for traveler’s diarrhea after a trip to Thailand. Pelvic exam reveals normal external genitalia and a gray, thin, malodorous vaginal discharge. There is no cervical motion tenderness or adnexal masses. What will most likely be seen in a saline wet mount examination of this patient’s vaginal discharge?

A 22-year-old woman seeks evaluation at a local walk-in clinic for lower abdominal pain, vaginal discharge, and painful intercourse over the last couple of weeks. The last day of her menstrual cycle was 1 week ago, and the pain has worsened since then. She describes it as severe. She is an out-of-town college student in an open relationship and has another partner from her hometown. She takes oral contraceptives and does not use condoms. Additional concerns include painful micturition and a low-grade fever for the same duration. Vital signs include temperature 38.6°C (101.5°F), heart rate 120/min, and respiratory rate 24/min. Pelvic examination shows an erythematous cervix with mucopurulent exudate. The cervix bleeds when manipulated with a swab and is extremely tender with movement. Which of the following is the most likely causative organism?

A 17-year-old boy presents to the pediatrician for an evaluation of his penis. He feels increasingly anxious during physical education (PE) class, as he has noticed that the size of his penis is significantly smaller than those of his peers. His height and weight are 175 cm (5 ft 9 in) and 60 kg (132 lb), respectively. Physical exam reveals that he is Tanner stage 1 and has difficulty identifying coffee grounds by smell. Which of the following is the most likely cause of his condition?

A 34-year-old man presents to a clinic with complaints of abdominal discomfort and blood in the urine for 2 days. He has had similar abdominal discomfort during the past 5 years, although he does not remember passing blood in the urine. He has had hypertension for the past 2 years, for which he has been prescribed medication. There is no history of weight loss, skin rashes, joint pain, vomiting, change in bowel habits, and smoking. On physical examination, there are ballotable flank masses bilaterally. The bowel sounds are normal. Renal function tests are as follows:

The patient underwent ultrasonography of the abdomen, which revealed enlarged kidneys and multiple anechoic cysts with well-defined walls. A CT scan confirmed the presence of multiple cysts in the kidneys. What is the most likely diagnosis?

A 10-year-old boy is brought to his pediatrician after discovering a painless mass in his left testicle. Results from tumor markers and a biopsy are as follows:

AFP 350 ng/mL (normal value < 10 ng/mL) hCG 0.4 IU/L (normal value < 0.5 IU/L) Biopsy Presence of glomeruli-like structures with a central capillary within a mesodermal core, lined by flattened layers of germ cells. What is the most likely diagnosis in this patient?

A 27-year-old woman presents to the office to discuss her struggle with her physical appearance since adolescence. She says she has always been “large” and was bullied by her classmates and coworkers. Her main concern at the moment is her acne and unwanted facial hair on her upper lip, for which she often visits a local esthetician. She has tried numerous diet plans, exercise regimens, and cosmetic products with little to no effect. Her menstrual cycle is irregular and occurs about every 45 days on average. She has a family history of type 2 diabetes mellitus in her mother. Recently, she had labs that showed a fasting plasma glucose level of 150 mg/dL and a hemoglobin A1c of 6.3%. Her height is 160 cm (5 ft 3 in), weight is 85 kg (187 lb), and body mass index (BMI) is 33.1 kg/m². Her pulse is 72/min and blood pressure is 138/80 mm Hg. On physical examination, she has severe inflammatory acne over the cheeks and forehead and dark coarse hairs on her back. What is the most likely diagnosis?

A 3-year-old boy presents to the office with his mother because of weakness and difficulty walking. He was born at 39 weeks gestation via spontaneous vaginal delivery. He is up to date on all vaccinations. He is meeting all verbal and social milestones, but gross and fine motor skills are delayed. Past medical history is noncontributory. He takes a multivitamin every day. His mother states that some boys on her side of the family have had similar symptoms and worries that her son might have the same condition. Blood pressure is 104/62 mm Hg, pulse is 90/min, respiratory rate is 22/min, and temperature is 37.0°C (98.6°F). On physical exam, the boy appears well-developed and pleasant. He listens and follows directions. His heart has a regular rate and rhythm and his lungs are clear to auscultation bilaterally. He struggles to get up to a standing position after sitting on the floor. Genetic studies reveal a deletion in the gene that codes for dystrophin. Which of the following is the most likely diagnosis?

A 4-year-old boy presents with a recent history of frequent falls. The images depict his movements when he tries to get up from the floor. Which of the following is the most likely diagnosis?

A 24-year-old woman recently noticed a mass in her left breast. The examination shows a 4 cm (1.6 in) mass in the left upper quadrant. The mass is firm, mobile, and has well-defined margins. She complains of occasional tenderness. There is no lymphatic involvement. Mammography shows a dense lesion. Her physical examination and vital signs are otherwise within normal limits. What is the most likely cause of the patient’s presentation?

A 45-year-old construction worker presents to his primary care physician with a painful and swollen wrist joint. A joint aspiration shows crystals, which are shown in the accompanying picture. The crystals are negatively birefringent in polarized light, meaning they are yellow under parallel light and blue under perpendicular light. What is the most likely diagnosis?

A 30-year-old man with a BMI of 33.7 kg/m2 presents with severe pain in his right great toe that began this morning. He had a few beers last night at a friend’s party but otherwise has had no recent dietary changes, and there is no history of toe or foot injury. On examination, the metatarsophalangeal (MTP) joint of the right great toe appears swollen, warm, red, and tender to touch. Joint aspiration is performed. What will examination of the synovial fluid most likely reveal?

A 27-year-old woman seeks evaluation for a malodorous yellow vaginal discharge and irritation for the past 3 days. She also complains of vaginal itching and soreness. The medical history is unremarkable. She has been sexually active with a single partner for the last 3 years. A vaginal swab is sent to the laboratory for microscopic evaluation and results are shown in the image. Culture yields heavy growth of protozoa. A pregnancy test is negative. What is the most appropriate treatment for this patient?

A 32-year-old woman presents with diplopia. She says that she has been experiencing drooping of her eyelids and severe muscle weakness. She reports that her symptoms are worse at the end of the day. Which of the following additional findings would most likely be seen in this patient?

A 5-year-old boy is brought to the emergency department by his foster mother because of multiple injuries. She says that he sustained these injuries while playing. Radiographic findings show multiple fractures in various stages of healing. She notes that he has always bruised easily. His family history is unknown. His blood pressure is 118/78 mm Hg, pulse is 76/min, and respirations are 15/min. Physical examination shows blue sclera. What is the most likely diagnosis in this patient?

A 70-year-old man presents to the outpatient clinic for a routine health checkup. He recently lost his hearing completely in both ears and has occasional flare-ups of osteoarthritis in his hands and hips. He is not diabetic and had hypertension for the past 25 years. His brother recently died of prostate cancer. His current blood pressure is 126/84 mm Hg. His cholesterol and prostate-specific antigen (PSA) levels are within normal limits. Flexible sigmoidoscopy and stool guaiac test results are negative. Serum calcium, phosphorus concentrations, and liver function test results are within normal limits. However, alkaline phosphatase (ALP) levels are increased by more than three times the upper limit. Radiography of the axial skeleton shows cortical thickening. What is the most likely diagnosis?

A 3-year-old boy presents with his parents to a pediatric urologist due to undescended testes. The physical examination shows an absent left testis in the scrotum. Inguinal swelling was noted on the left side and was surgically corrected. Which of the following conditions will most likely occur in the later stages of his life?

A 70-year-old man presents to a medical office with painful micturition for 2 weeks, but no other symptoms. The past medical history is unremarkable. He has been a smoker most of his life, smoking approx. 1 pack of cigarettes every day. The physical examination is benign. A urinalysis shows an abundance of red blood cells. A cystoscopy is performed, which reveals a slightly erythematous area measuring 1.5 x 1 cm on the bladder mucosa. A biopsy is obtained and microscopic evaluation shows cells with an increased nuclear/cytoplasmic (N:C) ratio and marked hyperchromatism involving the full thickness of the epithelium, but above the basement membrane. Which of the following best describes the biopsy findings?

A 31-year-old woman presents with painful vesicles on the right side of her torso. She notes that the lesions appeared two days ago and have not improved. One day prior to their appearance, she says that she experienced a burning sensation in the affected area. The patient is afebrile and vital signs are within normal limits. Upon physical examination, there are vesicles noted that are localized to the right T10 skin dermatome. Which of the following complications is associated with this woman’s likely diagnosis?

A 7-day-old newborn boy presents to the emergency department with a history of fever, irritability, and generalized erythema. During the first two days of clinical manifestations, the child’s parents tried to control the symptoms using acetaminophen; however, the newborn continued to be ill, and blisters were noticeable around the buttocks, hands, and feet. During the physical examination, his temperature is 39.0°C (102.3°F), pulse is 130/min, and respirations are 45/min. Ears, nose, and oral mucosa preserved their integrity, while the skin presents with diffuse blanching erythema and flaccid blisters with a positive Nikolsky sign. What is the most likely diagnosis in this patient?

A 26-year-old man presents to the office complaining of persistent back pain for the past three months. You saw the patient previously and prescribed non-steroidal anti-inflammatory drugs (NSAIDs) and rest, but he has not improved. The man states that his maternal grandfather had ‘back problems his whole life’, and he worries that he might have the same problem. An X-ray is performed and shows squaring of the vertebrae with longitudinal fibrous bands. What is the most likely diagnosis?

A 52-year-old woman presents to the clinic complaining of dry mouth for the past two months. She states that she drinks a lot of water but that her mouth is always dry. She says that she recently went to the dentist and had three cavities, which is more than she has ever had in her adult life. She has a history of type 2 diabetes and rheumatoid arthritis. Her vital signs are within normal limits. Her physical exam is unremarkable except that her sclerae are dry and erythematous, and she has a deformity in the joints of her hands, bilaterally. What is the etiology of this woman’s symptoms?

A 62-year-old carpenter presents to your clinic complaining of worsening joint pain in her hands. She states that the pain is present in all of her fingers, but is worse in the right hand and gets better when she has a few days off from work. She denies any paresthesias, fevers, or fatigue. Vital signs are normal. Physical exam reveals hard, non-tender lesions overlying the proximal interphalangeal joints of the 2nd and 3rd fingers of the right hand. All five digits of the right hand have a decreased range of motion. An X-ray of her hands is shown. What is the most likely pathogenesis underlying the X-ray findings?

A 45-year-old woman presents to the clinic complaining of weakness that has progressively worsened over the past two weeks. She states that she has a hard time lifting both her arms, but they otherwise function normally. She notes no history of trauma or other deficits. On examination, she has 2/5 muscle strength on shoulder shrug and arm abduction bilaterally, but the neurological exam is otherwise normal. You notice some skin changes and ask her about them. She states that she has had a rash around her eyes and on her lower face, going down to her neck and chest. The rashes started around the same time as the weakness began. A complete blood count and basic metabolic panel are normal. Which of the following is the most likely diagnosis?

A 15-year-old boy presents to the clinic complaining of an uncomfortable skin condition that started two years ago. The patient states that his skin feels “oily” and that he is embarrassed by his appearance. On examination, he is a healthy-looking teenager who has reached the expected Tanner stage for his age. The skin on his face and back is erythematous and shows signs of inflammation. What is the microbiologic agent most associated with this presentation?

A 2-month-old boy presents to the clinic with his mother for evaluation of crusty, greasy patches on the skin of the scalp that appeared one week ago. The mother states that the patient has been acting normally and is feeding well. She had a vaginal birth with no complications. On examination, the patient is smiling and playful in his mother’s arms. He can hold his head up, focus on faces, and is happily gurgling. Vital signs are stable, and weight, length, and head circumference measurements are all within normal limits for his age. The skin on the scalp appears greasy, with yellow, scaly patches. What is the most likely diagnosis?

A 75-year-old man presents to a medical clinic because of large, tense, pruritic bullae on his inner thighs and lower abdomen. Skin biopsy shows an epidermal basement membrane with immunoglobulin G (IgG) antibodies and linear immunofluorescence. What cell junction do the antibodies most likely bind to?

A 51-year-old man goes to his family physician with a complaint of heartburn, which has been gradually increasing over the last 10 years. The heartburn gets worse after eating spicy foods and improves with antacids. His past medical history is benign. He is a security guard and works long hours at night. He admits to smoking 1.5 packs of cigarettes every day. Upper gastrointestinal endoscopy reveals several gastric ulcers and regions of inflammation. A biopsy was obtained, which revealed gram-negative bacteria colonizing the surface of the regenerative epithelium of the stomach, as shown in the image. Which of the following products from this bacteria is responsible for neutralizing the acidity of the stomach?

A young girl who recently immigrated from Africa presents with low-grade fever, sore throat, painful swallowing, and difficulty breathing. Her voice has an unusual nasal quality, and her neck appears swollen. On examination, a large gray membrane is noticed on the oropharynx, as shown in the picture. Removal of the membrane reveals a bleeding edematous mucosa. Culture on potassium tellurite medium reveals several black colonies. What is the mechanism of action of the bacterial toxin responsible for this condition?

A 24-year-old sexually active man complains of red plaques on his penis. Biopsy shows squamous cells with perinuclear cytoplasmic vacuolization, nuclear enlargement, and koilocytes. The doctor treats the patient with cryoablation of the lesions and encourages his girlfriend to get tested. She may be at increased risk of which of the following malignancies?

A 54-year-old man presents with fever and a painful jaw mass with a yellowish discharge. He says that he first noticed the jaw mass six weeks ago and that it has been progressively increasing in size. He reports a history of chronic alcoholism and currently drinks more than six beers daily. His temperature is 37.9 °C (100.2 °F). On physical examination, there is a 7 × 7 cm (2.7 x 2.7 in) mass at the tip of the jaw bone with significant surrounding edema and sclerosis. The mass is severely tender on light palpation and has a yellowish malodorous discharge. The oral cavity shows signs of very poor dentition. Laboratory analysis of the discharge reveals gram-positive anaerobic filamentous bacteria. Which of the following organisms is the most likely cause of this patient’s condition?

A 65-year-old man presents with four months of low-grade fever and malaise. He also says he has lost 9 kg (20 lb) during this period and suffers from extreme fatigue. Past medical history is significant for a mitral valve replacement five years ago. His temperature is 38.1°C (100.6°F), respirations are 22/min, pulse is 102/min, and blood pressure is 138/78 mm Hg. On physical examination, there is a new onset 2/6 holosystolic murmur, loudest in the apical area of the precordium. Which of the following organisms is the most likely cause of this patient’s condition?

A 15-year-old girl presents to her primary care physician with her parents. She has been complaining of fever and a sore throat for the past four days. She was born at 39 weeks’ gestation via spontaneous vaginal delivery, is up to date with all vaccines, and meets all developmental milestones. Her boyfriend at school has the same symptoms. Today, her pulse is 90/min, respirations are 17/min, blood pressure is 110/65 mm Hg, and temperature is 38.2°C (100.8°F). Examination revealed cervical lymphadenopathy and mild hepatosplenomegaly. Oral exam reveals focal tonsillar exudate. A heterophile antibody test is positive. This patient is most likely infected with which of the following viruses?

A 22-year-old woman presents to her primary care provider with four days of an unrelenting headache accompanied by fever, chills, and malaise. She also complains of an earache and dry hacking cough. Past medical history is noncontributory. She takes oral contraceptives and a multivitamin with calcium daily. She drinks alcohol socially and smokes occasionally. Her temperature is 37.9°C (100.2°F), pulse is 104/min, respirations are 20/min, and blood pressure is 102/82 mm Hg. Physical exam reveals mild rhonchi in the lower lobes bilaterally. A chest X-ray shows bilateral patchy, diffuse interstitial infiltrates worst in the lower lobes. Sputum culture yields growth of an organism that is small, pleomorphic, and lacks a cell wall. Which of the following is the most likely pathogen?

A group of researchers conducted various studies on hepatitis C incidence and prevalence. They noticed a high prevalence of hepatitis C in developing countries, where it has a significant impact on the quality of life of the infected individual. The research group made several attempts to produce a vaccine that prevents hepatitis C infection, but all attempts failed. Which of the following would most likely be the reason for the failure to produce a vaccine?

Scientists are experimenting with the human cells involved in the immune response. They genetically modify B cells not to express the cluster of differentiation 21 (CD21) on their cell surfaces. The pathogenesis of which of the following organisms would most likely be affected by this genetic modification?

A 14-year-old girl presents with sudden drooping of the right side of her face with drooling and excessive tearing. The patient’s mother says that the patient was recently in northern Maine and spent most of her time during the trip outdoors. Physical examination reveals a slight asymmetry of the facial muscles with an inability to whistle or close the right eye. A circular red rash with central clearing is present on the trunk. There is also a decreased taste sensation. Which of the following most likely transmitted the organism responsible for this patient’s illness?

A 12-year-old girl presents to the pediatric dermatologist with an expanding but otherwise asymptomatic erythematous patch on her right shoulder, which she first noticed three days ago. The girl states the rash started as a small red bump but has gradually progressed to its current size. No similar lesions were observed elsewhere by her or her mother. She has felt ill, and her mother has detected intermittent low-grade fevers. During the skin examination, a target-like erythematous patch, approximately 7 cm in diameter, was noted on the left shoulder (as shown in the image). Another notable finding was axillary lymphadenopathy. On further questioning, it was revealed that the patient went camping with her grandfather approximately 11 days ago; however, she does not recall any insect bites or exposure to animals. The family has a pet cat living in their household. Based on the history and physical examination results, what is the most likely diagnosis?

An 8-year-old child is brought to the emergency department because of profuse diarrhea and vomiting for the past two days. The boy was born at 39 weeks’ gestation via spontaneous vaginal delivery. He is up to date on all vaccines and is meeting all developmental milestones. Past medical history is noncontributory. The family recently made a trip to India to visit relatives. Today, his pulse is 100/min, respirations are is 22/min, blood pressure is 105/65 mm Hg, and his temperature is 37.2°C (99.0°F). On physical examination, he appears unwell with poor skin turgor and dry oral mucosa. His heart has a regular rate and rhythm, and his lungs are clear to auscultation bilaterally. His abdomen is sensitive to shallow and deep palpation. A gross examination of the stool reveals a “rice water” appearance. Diagnostic microbiology results are pending. What is the next best step in management?

A 24-year-old woman presents to her gynecologist complaining of mild pelvic discomfort and frothy, yellowish discharge from her vagina for the past two weeks. She also complains of pain during sexual intercourse and sometimes after urination. Her past medical history is noncontributory. She takes oral contraceptives and a multivitamin daily. She has had two male sexual partners in her lifetime and uses condoms inconsistently. Today, her vitals are normal. She has vulvovaginal erythema and a “strawberry cervix” that is tender to motion, with minimal green-yellow malodorous discharge on pelvic exam. A swab of the vaginal wall is analyzed for pH at the bedside. Vaginal pH is 5.8. Which of the following is the most likely diagnosis for this patient?

A 30-year-old woman presents to her primary care provider complaining of intermittent fever and loss of appetite for the past two weeks. She also reports painful genital lesions. Past medical history is noncontributory. She takes oral contraceptives and a multivitamin daily. She admits to being sexually active with two partners in the last three months and uses condoms inconsistently. Vital signs are within normal limits. On pelvic exam, there are red-rimmed, fluid-filled blisters over the labia minora with swollen and tender inguinal lymph nodes. Which of the following is the most likely diagnosis?

An 18-year-old woman makes an appointment for her first gynecologic evaluation. She does not disclose her sexual history but had unprotected sex with her boyfriend three weeks ago. She is now complaining of a yellow-green, diffuse, malodorous vaginal discharge that she noticed one week ago for the first time. She also reports mild pelvic and abdominal pain. Pelvic exam reveals cervical motion tenderness and an inflamed cervix with a preponderance of small red punctate spots. There is a frothy white discharge with a malodorous odor in the vaginal vault. A wet mount is prepared for light microscopy, which reveals numerous squamous cells and motile organisms. Which of the following is the most likely causative organism?

A 21-year-old man presents to a physician because of extreme fatigue, palpitations, fever, and weight loss. He developed these symptoms gradually over the past three months. His blood pressure is 110/80 mm Hg, pulse is 109/min, respirations are 17/min, and the temperature is 38.1°C (100.6°F). The patient is emaciated and pale. There are conjunctival hemorrhages, and several bruises noted bilaterally in the inner cubital area. There are also a few lesions on the left foot. The cardiac examination reveals a holosystolic murmur best heard at the 4th intercostal space at the left sternal edge. Two blood cultures grew Staphylococcus aureus, and echocardiography shows a tricuspid valve aneurysm. Which of the following would most likely be revealed in a detailed history from this patient?

A 31-year-old woman presents with dysuria and pain in her lower abdomen. It is the first time she has experienced such symptoms. She denies a history of any genitourinary or gynecologic diseases. The blood pressure is 120/80 mm Hg, pulse is 78/min, respirations are 13/min, and temperature is 37.0°C (98.6°F). The physical examination is within normal limits. A urine culture grew the pathogens pictured. The presence of which of the following factors specifically allows this pathogen to cause urinary tract infections?

A 41-year-old woman presents with occasional dyspareunia and vaginal bleeding after a sexual encounter. She is in a monogamous relationship and uses oral contraception. She does not have a family history of gynecologic malignancies. She has smoked one pack of cigarettes per day for 15 years and drinks several glasses of wine each day. She has not received an HPV vaccination. Her blood pressure is 120/70 mm Hg, pulse is 71/min, respirations are 14/min, and the temperature is 36.7°C (98.1°F). A speculum examination shows a nulliparous cervix in the mid-plane of the vaginal vault with a red discolouration – approx. 1 × 2 cm (0.4 x 0.8) in diameter. Bimanual examination revealed no apparent pathologic changes. The Papanicolaou smear shows intensely stained eosinophilic cells with prominent nucleoli and mitotic activity and is suggestive of cervical adenocarcinoma. Gene coding for which of the following proteins is most likely to be mutated in the affected cells in this case?

A 20-week-old infant is brought to an urgent care clinic by her mother because she has not been eating well for the past 2 days. The mother said her daughter has also been ‘floppy’ since yesterday morning and has been unable to move or open her eyes since the afternoon of the same day. The child has recently started solid foods, like cereals sweetened with honey. There is no history of loose, watery stools. On examination, the child is lethargic with lax muscle tone. She does not have a fever or apparent respiratory distress. What is the most likely mode of transmission of the pathogen responsible for this patient’s condition?

A 7-year-old boy is brought to a pediatric clinic by his mother because he had difficulty swallowing for four days. He was diagnosed with asthma three months ago and used an inhaler as directed by the paediatrician. The child does not have a fever or a cough and is not short of breath. His temperature is 37℃ (98.6℉), respirations are 14/min, blood pressure is 90/40 mm Hg, and pulse is 80/min. The oral examination reveals a slightly raised white lesion over his tongue and oropharynx suggestive of oral thrush. What is the most likely diagnosis?

A 10-year-old boy is brought to the pediatric clinic because of a sore throat of a 1-week duration. He also has a cough and fever. He has pain when swallowing and sometimes water regurgitates from his nose when drinking. His immunization status is unknown as he recently moved to the US from Africa. On examination, he is alert and oriented to time, place, and person. On inspection of his oral cavity, an edematous tongue with a grey-white membrane on the soft palate and tonsils is noted. The neck is diffusely swollen with bilateral tender cervical lymphadenopathy. Which of the following is the cause of this patient’s condition and could have been prevented through vaccinations in early childhood?

A 6-year-old girl is brought to a clinic with complaints of fever and sore throat for two days. This morning, she developed a rash in her armpits, which is progressing towards the trunk. The teachers in her school report that none of her classmates has similar symptoms. She has a normal birth history. On physical examination, the child looks healthy. Her pulse is 135/min, respirations are 20/min, the temperature is 39.0°C (102.2°F), and blood pressure is 90/50 mm Hg. An oropharyngeal examination reveals circumoral pallor with a red tongue. The chest and cardiac examinations are within normal limits. No hepatosplenomegaly is noted. What is the most likely diagnosis?

A 62-year-old man is referred to a gastroenterologist because of difficulty swallowing for the past five months. He has trouble swallowing both solid and liquid foods, but there is no associated pain. He denies any shortness of breath or swelling in his legs. He immigrated from South America ten years ago. He is a non-smoker and does not drink alcohol. Physical examination is unremarkable. A barium swallow study was ordered and the result is shown. Esophageal manometry confirms the diagnosis. Which of the following is the most likely diagnosis?

During a humanitarian medical mission trip in rural Vietnam, a medical resident encounters a 50-year-old man with a year-long history of a pruritic rash on his upper body and face, along with numbness and tingling sensation of both of his palms. He mostly works on his family’s rice farm, where he also takes care of livestock. A physical examination revealed multiple erythematous macules and papules on the face, arms, chest, and back, as well as thinning of the eyebrows and loss of some eyelashes. Additional findings include hypopigmented macules around the elbows, which are insensitive to light touch, temperature, and pinprick. His grip strength is slightly diminished bilaterally and he has normal bilateral biceps deep tendon reflexes. What is the most likely diagnosis?

A 1-year-old boy presents to the clinic due to a peeling erythematous rash on his face, back, and buttocks. According to the mother, his skin was extremely tender two days ago and quickly progressed to desquamation. She also says that he was very irritable for the past few weeks and cried more than usual during diaper changes. He is up to date on his vaccinations and has been meeting all developmental milestones. There is no significant family history. His temperature is 38.4°C (101.1°F) and pulse is 150/min. The top layer of the skin sloughs off with gentle lateral stroking of the skin. Systemic antibiotics are prescribed, and adequate fluid replacement is provided. Which of the following microorganisms most likely caused this patient’s condition?

A 20-year-old woman presents with vaginal discharge, pruritus, and painful urination for the past five days. She is sexually active with multiple partners and admits to using barrier protection inconsistently. Her last menstrual period was two weeks ago. The patient denies fever, chills, abdominal pain, menorrhagia, or flank pain. She is afebrile, and the vital signs are within normal limits. Speculum examination reveals cervical erythema with a profuse, greenish-yellow, purulent, malodorous discharge. The vaginal pH is 5.5. Vaginal swab and urine samples are obtained for microscopy and culture, and results are pending. Which of the following is the most likely diagnosis in this patient based on her presentation?

A 23-year-old gravida 1-para-1 (G1P1) presents to the emergency department with severe lower abdominal pain that started several hours ago. She reports fever, malaise, and nausea for the last 2 days. Her last menstrual period was 3 weeks ago. Her past medical history has no pertinent findings. She has had 3 sexual partners in the past month and uses oral contraception. Her vital signs include temperature 38.8°C (101.8°F) and blood pressure 120/75 mm Hg. The physical examination is positive for tenderness to light palpation of the lower abdominal quadrants as well as for uterine and adnexal tenderness elicited on pelvic exam. On speculum examination, the cervix is erythematous, with yellow-white purulent discharge. Urine pregnancy test is negative. Which of the following is the most likely diagnosis?