JCAT Mock 1

A 16-year-old girl comes to the office for the evaluation of absent menses. The patient has not had a menstrual period yet but is otherwise healthy. Past medical history is noncontributory. Vitals are within normal limits. Physical examination shows appropriate breast development and growth of pubic and underarm hair. The patient declined a vaginal exam. Karyotype analysis reveals 46 XX. Pregnancy test is negative; thyroid stimulating hormone, prolactin, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels are normal. Pelvic ultrasound shows 2 normal-sized ovaries but no uterus. Which of the following is the most likely underlying pathophysiology of this patient’s condition?

A 17-year-old girl comes to the office for a routine medical examination. Her medical history is relevant for a karyotype of 45, X0. The patient takes growth hormone, estrogen, and progesterone hormone replacement. Physical exam shows morbid obesity (BMI >40), short stature, webbed neck, parvus et tardus pulse, and a systolic heart murmur located at the right second intercostal space. Her temperature is 36.6°C (97.8 °F), the pulse is 56/min, respirations are 28/min, blood pressure is 120/84 mmHg, and pulse oximetry on room air shows an oxygen saturation of 95%. Which of the following is most likely related to this patient’s physical findings?

A 2-year-old boy is brought to the clinician by his parents due to easy fatigability and growth delay. They recently immigrated to the United States. The mother did not receive any prenatal care in her home country. The child was born at term by a normal vaginal delivery. He is at the 30th percentile for length and below the 10th percentile for weight. Temperature is 37.2°C (98.9°F), pulse is 115/min, respirations are 25/min, and blood pressure is 85/60 mmHg. Abdominal examination shows hepatosplenomegaly. Laboratory testing is obtained and the patient is diagnosed with β-thalassemia major. The patient is given the appropriate treatment and his condition dramatically improves. Which of the following is a likely long-term complication resulting from this treatment?

A 21-year-old man comes to the emergency department because he has been unconscious for the past 20 minutes. His friends tell you he collapsed at a nightclub He was initially conscious but was unable to move one side of his body. His temperature is 37.5°C (99°F), pulse is 96/min; respirations are 16/min, and blood pressure is 154/86 mm Hg. Examination shows a Glasgow coma score of 4 (E1V1M2). His left pupil is fixed and dilated, and there is redness around the nares bilaterally. Which of the following is the most likely vascular malformation?

A 22-year-old woman goes to an urgent care center for evaluation of left ear pain. The patient recently travelled to Las Vegas for a friend’s bachelorette party, and upon returning, noticed her ear had become red, itchy, and painful. She also has difficulty hearing out of the left ear. Past medical history is notable for chronic ear infections as a child. The patient takes only birth control pills. Vital signs are within normal limits. Otoscopic examination reveals an erythematous ear canal and the presence of yellowish-grey cerumen. The tympanic membrane is mildly erythematous but nondistended. Pain is elicited with manipulation of the pinna. Further discussion with the patient will most likely reveal which of the following historical features?

A 30-year-old man is brought to the emergency department for abdominal pain and tenderness that have been worsening over the past seven hours. He rates the pain as an 8 on a 10-point scale, and says that the pain is worse when he coughs. It is diffuse across his whole abdomen and does not radiate to other regions of the body. He denies prior similar episodes. On physical exam, the abdomen feels rigid and there is a positive Blumberg sign. Which of the following is the most likely diagnosis?

A 30-year-old woman comes to the office because of fatigue. She reports dry skin, increased hair loss, and constipation. She says that she has gained more than 4.5-kg (10-lb) over the past few months, and she has missed her period for the last two months. Her respirations are 12/min, her blood pressure is 115/92 mmHg, and her BMI: 28 kg/m². Obtaining which of the following laboratory values would be the next best step in diagnosing this patient?

A 32-year-old male is brought to the emergency department after being involved in a high speed motor vehicle collision. Per paramedics, the patient was the restrained driver and was rear-ended by another vehicle traveling approximately 60 miles per hour. The patient endorses difficulty moving his arms and legs, and endorses pain to the back of his neck. He is otherwise healthy and does not take any medications. Temperature is 37.0°C (98.6°F), pulse is 42/min, respirations are 17/min, blood pressure is 80/60 mmHg, and O₂ saturation is 97% on room air. On physical exam, the patient has a large bruise over the anterior chest wall and abdomen. Cardiopulmonary exam is otherwise unremarkable. He is unable to move his arms or legs to command and has absent reflexes below the C6 level. Which of the following best describes the underlying pathophysiology resulting in this patient’s clinical presentation?

A 34-year-old woman comes to her outpatient provider’s office for evaluation of recent skin changes. Past medical history is notable for seasonal allergies. She is not currently taking any medications. Her father passed away from a myocardial infarction at 32-years-old, and her mother has type 2 diabetes mellitus. Her paternal grandfather passed away from colorectal cancer at 62-years-old. Her vitals are within normal limits. Physical examination shows several subcutaneous nodules found above the Achilles tendon bilaterally. Laboratory testing reveals the following findings:

A 35-year-old man is brought to the emergency department by his roommate for evaluation of disorganized behavior. Two days ago, the patient refused to come out of his room claiming, “I have a plan to rid the world of climate change!” The patient has been refusing to eat or sleep. The roommate states, “I’m also missing my prescription for my ADHD.” The patient has a history of major depressive disorder and allergic rhinitis. His current medications include escitalopram and an over the counter nasal decongestant. He does not use tobacco or alcohol. Temperature is 100 °F (37.7 °C), pulse is 110 bpm, and blood pressure is 150/80 mmHg. The patient appears agitated and irritable. On physical examination, the pupils are mydriatic, and the patient is diaphoretic. Oral mucosa appears moist. No clonus is elicited in the bilateral lower extremities. Which of the following is the most likely diagnosis?

A 36-year-old woman comes to the clinic because of blood in her urine for the past 4 days. She also complains of painful urination, an increased urge to urinate, and an involuntary loss of urine. Physical examination shows suprapubic tenderness. Blood pressure is 123/84 mm Hg. Urinalysis shows 2+ blood, a positive urine leukocyte esterase test, and a positive nitrite test. Urine gram stain shows an organism count of >100,000/mm³. Which of the following is the most likely diagnosis?

A 38-year-old man comes to the office because of a persistent headache that has worsened in the last three days. His temperature is 38.1°C (100.6°F), pulse is 75/min, respirations are 12/min, and blood pressure is 120/75 mm Hg. He requests that the lights be dimmed. Acetaminophen helps with the pain temporarily. He has also been sweating profusely at night and says his muscles ache. Rales are heard on auscultation. He is the owner of a pet store, where he began remodeling the aviary last week. He does not know of any sick contacts. Which of the following is the most likely diagnosis?

A 38-year-old previously healthy man is referred to the office for the evaluation of pleuritic chest pain. His medical history is only relevant to a recent trip to South America. Upon medical interrogation, the patient denies abdominal pain or gastrointestinal disturbances. Shortly after his return, he started with an episode of wheezing and dyspnea, pleuritic chest pain, and productive cough with rusty colored sputum. The patient claims that this episode was short lived and resolved on its own. Physical examination reveals inspiratory crackles and a mild rash over his chest. Laboratory tests show a moderate eosinophilia (3400/mm³). Which of the following is the most likely causal organism?

A 40-year-old woman is brought to the emergency department following head trauma secondary to a ski accident. The patient slammed headfirst into a tree and was found unresponsive at the scene. Temperature is 37.0°C (98.6°F), pulse is 45/min, respirations are 8/min and irregular, and blood pressure is 190/70 mmHg. Glasgow coma scale is 8, and she is subsequently intubated and mechanically ventilated. On physical examination, there is a bruise noted to the left side temporal area. The left eye is abducted with downward displacement. The left pupil is dilated and areflexic to light. A non-contrast CT is obtained and shows a large, lens-shaped lesion with midline shift. Which of the following describes an early complication of this condition?

A 52-year-old woman comes to her primary care physician for evaluation of a painless mass that emerged on her right forearm several months ago. She has not had any recent trauma to the area. Past medical history is notable for rheumatoid arthritis and hypertension. Vitals are within normal limits. Physical examination of the hands reveals bilateral swelling and reduced range of motion in the metacarpophalangeal and proximal interphalangeal joints. Examination of the patient’s right forearm reveals the following finding:

A 58-year-old woman comes to the office because of progressively worsening abdominal pain during the past 4 months. She also reports bloating and difficulty eating. Menopause occurred 7 years ago. She takes no medications. Physical examination shows a right adnexal mass, visualized as a multilocular mass on pelvic ultrasound. The patient undergoes surgical exploration, which identifies a cystic ovarian mass and residual foci of endometriosis. Histopathology shows a villoglandular architectural pattern, with glands lined by stratified columnar cells with scant eosinophilic cytoplasm. Which of the following is the most likely diagnosis?

A 22-year-old male comes to the office because of urinary incontinence for 2 days. He states that he has wet himself while at work two days in a row, and feels that something must be wrong. He says he has also had central back pain for 4 months, which is worse when lying down. Otherwise, he has felt well. Medical and family histories are noncontributory. Examination shows normal male external genitalia. Neurological examination shows that there is reduced sensation to both pain, and temperature at the level of the umbilicus. Which of the following is the most likely diagnosis?

A 22-year-old woman is brought to the office by her partner due to hand tremors and a clumsy gait, which have progressively worsened over the last 4 months. Past medical history is noncontributory. She lives with her partner, who has noticed that she has become more withdrawn lately. The patient does not drink alcohol, smoke cigarettes, or use illicit substances. Vital signs are within normal limits. Her BMI is 20 kg/m². During the physical examination, the patient exhibits a flat affect while speaking. Her liver is palpated 4 cm below the costal margin and is mildly tender. No palmar erythema, spider angiomata, or ascites is noted. A resting tremor is present in the bilateral hands. Further physical examination of this patient would most likely reveal which of the following?

A 61-year-old woman is brought to the emergency department by her daughter with acute left-sided facial weakness, dizziness, and loss of pain and temperature sensation of the left side of her face and right side of her body. She also says that her mouth and eyes are dry, and she could not taste the food she was eating prior to the onset of these symptoms. Past medical history is significant for hypertension, diabetes mellitus, and atrial fibrillation. She has smoked 1 pack of cigarettes daily for the last 30 years. Physical examination shows absent corneal reflex on the left side, nystagmus, ataxia, and dysmetria. Which of the following is the most likely diagnosis?

A 34-year-old man comes to the clinic because of skin changes and numbness in his hands and feet for the past few months. For the past three years, he has worked as a zookeeper, spending most of his time with the armadillos. He says that his skin, especially on his face, has gradually begun to develop folds and feel tough. His temperature is 38.3°C (101.5°F), pulse is 82/min, respirations are 14/min, and blood pressure is 132/84 mm Hg. Physical examination shows leonine facies, diffuse skin changes, and loss of sensation in the distal upper and lower extremities. A skin biopsy is performed and shows acid-fast bacilli invading a cutaneous nerve. Which of the following is the most likely cause of this condition?

A 35-year-old man is brought to the emergency department by EMS after he was found at a public park yelling at bystanders. Several unlabeled pill capsules are found in his belongings. Temperature is 100°F (37.7 °C), pulse is 117 bpm, respiratory rate is 18 breaths per minute, and blood pressure is 177/90 mmHg. The patient appears agitated and diaphoretic. On physical examination, the patient has noted mydriasis bilaterally. There is absence of clonus in the lower extremities bilaterally. Oral mucosa appears moist. Intranasal examination reveals septal ulceration. Which of the following is the most likely etiology of this patient’s clinical presentation?

A 13-year-old girl comes to the office because she is concerned about not getting her first menstrual cycle. Her older sister had menarche at age 11. She states that she has also noticed that her voice has been getting deeper. Examination shows partial labial fusion, with clitoromegaly, and partially descended testes. Laboratory investigations show that the karyotype is 46 XY. Ultrasound scanning shows neither ovaries, nor a uterus. Which of the following best explains the direct cause of this patient’s condition?

A 40-year-old woman comes to the clinic due to vaginal lesions, bleeding, and pruritus. Medical history is significant for type 2 diabetes mellitus and hypertension. The patient has smoked 1 pack of cigarettes per day for the past 20 years. She does not use alcohol excessively and has no history of sexually transmitted diseases. The patient has had 4-lifetime sexual partners and used condoms inconsistently. She has been in a monogamous relationship with her partner for the past 15 years. The patient has regular menstrual cycles; the last period was two weeks ago. In the office, the patient’s temperature is 37.5°C (99.5°F), pulse is 72/min, and blood pressure is 135/84 mmHg. On physical examination, 2 foci of ulcerated, warty-like, fleshy masses that easily bleed are observed over the left labia majora. Following a biopsy, the diagnosis of vulvar carcinoma is confirmed. Further history will most likely reveal which of the following?

A 22-year old college student comes to the office because of a 3-week history of progressive back pain. The patient is currently taking aspirin.  His medical history is noncontributory. When asking the patient about symptom description, he mentions that his pain is worse at night and he has no relief with aspirin. Upon further interrogation, the patient denies history of trauma, fever or any other disease. Physical exam shows limited range of motion of his spine and spinal tenderness at C5 and C6 levels. His temperature is 36.1°C (96.9°F), pulse is 84/min, respirations are 15/min, and blood pressure is 110/70 mmHg. A plain spine radiograph shows a 3 cm, well-circumcised radiolucent area surrounded by rim area of sclerosis at C5. Which of the following is the most likely cause of this patient’s current condition?

A 15-year-old girl comes to the office with her mother for a routine health checkup. The patient has not had a menstrual period yet but is otherwise healthy.  She wears corrective spectacles for myopia. The patient performs well academically and plays the flute in her school’s marching band. The patient’s height and weight are at 5th and 60th percentile, respectively. Temperature is 37°C (98.6°F), pulse is 95/min, respirations are 18/min and blood pressure is 150/85 mmHg in the right upper arm and 90/65 mmHg in the left upper arm. Physical examination shows a Tanner stage I breast with widely-spaced nipples. Serum FSH is 65 mU/mL. Which of the following is the most likely underlying cause of this patient’s condition?

A 30-year-old woman comes to the office because of intermittent diarrhea that has been recurring over the past two months. She has noticed blood in her stool and has had occasional abdominal cramps and nausea. Her temperature is 37.2°C (99°F). Colonoscopy shows skip areas of involvement with a predominance of focal ulcerations in the terminal ileum. Which of the following gene mutations most likely confers susceptibility to this patient’s disease?

A 35-year-old man comes to the office due to difficulty swallowing, food regurgitation, and chest pain for the past several months. The patient describes difficulty swallowing both liquids and solids. He often regurgitates large pieces of undigested food mixed with saliva. History is notable for drinking 2 beers every evening and smoking 1 pack of cigarettes per day for the past 5 years. He has had no recent illness, weight loss, or fatigue. He has not traveled out of the country recently. Vital signs are within normal limits. Physical examination, including cardiopulmonary examination, is normal. Which of the following is the most likely diagnosis?

A 44-year-old woman comes to the clinic with fatigue, weight loss, and nausea. Over the past six months, she has felt her energy gradually decrease, and she now gets tired walking one city block. She has lost her appetite for most foods except french fries and potato chips. Every few days, she experiences a wave of nausea and cramping abdominal pain that causes her to vomit. Family history is significant for autoimmune hypothyroidism in her mother. His/her temperature is 37.0°C (98.6°F), pulse is 80/min, respirations are 18/min, and blood pressure is 90/60 mmHg. Physical examination shows a thin female with a non-distended, minimally tender abdomen. Oral examination shows the following:

A 32-year-old man comes to his outpatient provider because of headaches that began five-months ago. The patient reports that the headaches are worse in the morning and improve over the day. In addition, the patient endorses reduced body hair. He does not use any medications. Temperature is 37.4°C (99.3°F), pulse is 68/min, respirations are 20/min, and blood pressure is 125/72 mmHg. Physical exam is notable for restricted peripheral vision and white watery discharge from the nipples. Further review of the patient’s history will most likely reveal which of the following findings?

A 52-year-old homeless man comes to the emergency department because of several episodes of severe bloody diarrhea. He is responsive only to painful stimuli and is unable to answer questions. His temperature is 39.2°C (102.6°F), pulse is 125/min, respirations are 8/min, and blood pressure is 86/54 mm Hg. Physical examination shows marked lower abdominal distension. A complete blood count shows a hemoglobin concentration of 6.5 g/dL, hematocrit of 25%, and a leukocyte count of 14,000/mm³. Despite aggressive antibiotic treatment and multiple blood transfusions, he passes away. An autopsy shows extensive, continuous inflammation and necrosis of the distal colon from the sigmoid colon to the rectum. Which of the following is the most appropriate diagnosis?

A 30-year-old woman, gravida 2 para 1, at 20 weeks gestation comes to the physician due to abdominal discomfort and early satiety for the past few days. She denies headache, visual changes, cramping or vaginal bleeding. Fetal movement is normal. Medical history is unremarkable. Abdominal ultrasound reveals a homogenous, well-demarcated, hyperechoic mass within the left lobe of the liver. A decision is made to follow up on the lesion post-partum. The follow-up ultrasound obtained 3 months after delivery shows an increase in the mass size without changes in the appearance. Which of the following is the most likely diagnosis?

A 55-year-old healthy man comes to the office because of an evolving nevus. He states it has been present on the dorsum of his right hand for “quite a while,” but it started growing in size and changing color recently. He has been a gardener for the past 20 years and spends much of his time working outdoors. Physical examination shows a hyperpigmented lesion on the dorsum of the right hand with irregular borders, measuring 8-mm in diameter. Excisional biopsy of the lesion reveals the following findings on histopathology.

A 40-year-old man comes to the emergency department because of fever and muscle rigidity. He reports having taken haloperidol 6 hours ago. Physical examination shows his temperature is 39.4°C (103°F), he is diaphoretic and has diffuse muscle rigidity. Over the next day, the patient continues to deteriorate, becoming more obtunded and showing fluctuating increases in his blood pressure. Which of the following is the patient’s most likely diagnosis?

An autopsy is being performed on a 57-year-old man who was found unresponsive on the kitchen floor by his daughter. His medical history is remarkable for a 30 pack year smoking history. The pathologist notes small, red punctate lesions at the upper level of the pons. These findings are associated with which of the following cerebral pathologies?

An 87-year-old woman is brought to the emergency department from a nearby skilled nursing facility with confusion and vomiting for the past day. According to the nursing staff, the patient was in her usual state of health before the last 24 hours, during which she was complaining of nausea. She is normally alert and oriented to person, place and time. She has a past medical history of diabetes and hypertension, and she was recently discharged from the hospital after having an obstructed kidney stone removed and a postoperative course complicated by recurrent urinary retention. Her temperature is 38°C (100.4°F), pulse is 107/min, respirations are 22/min, blood pressure is 121/64 mmHg, and oxygen saturation is 96% on room air. She is oriented to person but not to place or time. Physical examination shows tenderness to palpation over her left flank. A Foley catheter is in place and draining dark brown urine. Which of the following is the strongest risk factor for this patient’s current clinical condition?

A 65-year-old man comes to clinic because of urinary incontinence for the past 2 weeks. He describes having difficulty initiating urination or telling when or if his bladder is full or empty. He denies frequency, urgency, or bowel dysfunction. Past medical history is significant for stroke 1 year ago in addition to hypertension and coronary artery disease. Past surgical history is significant for lower back surgery 1 month ago after a car accident. Physical examination shows decreased sphincter tone and 110 ml of post-void residual urine. Diagnostic tests show normal bladder capacity, no sign of infection, normal prostate-specific antigen levels, and normal creatinine. Which of the following is the most likely diagnosis?

A 65-year-old man comes to the physician’s office due to a recent fall and the feeling of unsteadiness. The patient fell 2 days ago when going down the stairs but did not experience any head trauma. The patient’s partner reports that the patient has been acting differently for the past several months and is often anxious. The patient is healthy with no significant past medical history, and he does not take any medications. Vital signs are within normal limits. On physical examination, there is mild hyperkyphosis, and the patient is walking slowly. The muscle tone is increased bilaterally. There is a mild tremor on the right hand during rest which disappears on a finger-to-nose test. The patient is started on appropriate therapy. Which of the following is most likely to be found on examination of a patient’s brain with this condition?

A 9-year-old girl is brought to the clinic by her father because of a mass on her neck for the past two months. He says that since he first noticed the mass, it seems to have steadily grown in size. She has not had any recent illnesses and has not complained of pain. The patient’s medical history is noncontributory. Her temperature is 37.0°C (98.6°F), pulse is 82/min, respirations are 10/min, and blood pressure is 118/72 mm Hg. Physical examination shows a 3 x 3 cm nontender mass on the left side of her neck over the sternocleidomastoid along with multiple abnormally enlarged lymph nodes nearby. A biopsy of the mass is performed and shows positive staining with desmin. Further evaluation shows the presence of desmin within the lymph nodes as well. Which of the following is the most likely diagnosis?

A 65-year-old man comes to the emergency department because of a sudden onset of chest pain and dizziness. He has a history of uncontrolled hypertension, hyperlipidemia, alcohol abuse, and a family history of coronary artery disease. He currently takes enalapril, simvastatin, and low-dose aspirin. His temperature is 35.3°C (95.5°F), the pulse is 110/min, respirations are 30/min, blood pressure is 80/60 mm Hg, and pulse oximetry on room air shows an oxygen saturation of 90%. He looks pale and diaphoretic and when his head is positioned at 45°, the filling level of the external jugular vein is 9 cm vertical height above the sternal angle. His heart sounds are clear and he has no extra cardiac sounds on examination, nor rales on pulmonary examination. There is no change in blood pressure on inspiration. An electrocardiogram reveals ST-elevation in the right precordial leads. This clinical presentation is most consistent with which of the following conditions?

A group of students is studying gluteal and thigh anatomy. The students identify the primary nerve that innervates the gluteus maximus muscle. Which of the following statements regarding this nerve is true?

A 70-year-old man comes to the office because of increasing shortness of breath on exertion for 3 months. Past medical history includes poorly controlled diabetes and hypertension. Temperature is 36.5°C (97.7°F), pulse is 82/min, respirations are 14/min, and blood pressure is 122/83 mm Hg. Examination shows a loud ejection systolic murmur which radiates to the carotid vessels. Which of the following is the most likely conduction abnormality seen on his ECG?

A newborn female is delivered at 30 weeks gestation and presents with expiratory grunting and cyanosis in the neonatal intensive care unit. Her temperature is 37.2°C (102.6°F), pulse is 225/min, and respirations are 85/min. Physical examination shows nasal flaring and chest wall retractions. Chest x-ray shows a “bell-shaped chest,” a small, uniform right lower lobe infiltrate, and air-bronchograms. Which of the following interventions could have been used to prevent this patient’s clinical condition?

A 59-year-old man comes to the clinic for evaluation of worsening productive cough and fevers over the last few days. The patient has a past medical history of hypertension that is well-controlled with metoprolol. He recently completed a course of antibiotics for cellulitis of the left shin. He actively smokes, has a 15-pack-year smoking history, and drinks 2-3 beers on the weekends. He rarely exercises. Temperature is 38.5°C (101.3°F), pulse is 101/min, respirations are 16/min, and blood pressure is 125/85 mmHg. Physical examination reveals dullness to percussion and bronchial breath sounds over the left lung. Chest radiograph demonstrates a left lower lobe consolidation. Sputum microscopy shows Gram-positive diplococci. Which of the following is the most important risk factor for this patient’s current condition?

A 32-year-old man presents to the clinic with increasing lower back pain. He reports his pain is worse in the morning and improves with exercise. His other past medical history is notable for ulcerative colitis. He undergoes testing for HLA-B27, and his results are positive. On follow up several years later, the patient reports worsening shortness of breath with exertion. Which of the following pulmonary parameters is most likely to be normal in this patient?

A 16-year-old boy presents to his pediatrician for evaluation of sore throat. Around a week ago, he began experiencing difficulty swallowing due to pain. He has also had associated fevers, fatigue, and anorexia. The patient is otherwise healthy and does not take any medications daily. He does not consume tobacco, alcohol, or illicit substances. The patient is sexually active with one female partner. Temperature is 38.3°C (100.9°F), pulse is 101/min, respirations are 16/min, and blood pressure is 120/71 mmHg. Physical examination demonstrates tender posterior auricular and posterior cervical lymphadenopathy, as well as bilateral tonsillar swelling with exudates. A screening heterophile antibody test returns positive. Which of the following clinical features represents a potentially life-threatening complication of this patient’s condition?

A 30-year-old woman is brought to the emergency department due to progressive fatigue and shortness of breath for the past few hours. A week ago, she had an upper respiratory infection, and since then, she has not recovered completely. Medical history is significant for smoking half-a-pack of cigarettes daily and drinking 3 beers a week but is otherwise unremarkable. Medications include oral contraceptives and ibuprofen for occasional migraine headaches. Temperature is 37.0°C (98.6°F), pulse is 122/min, respirations are 20/min, and blood pressure is 85/60 mmHg. Pulse oximetry shows an oxygen saturation of 98% on room air. Physical examination reveals jugular venous distension. When the patient inhales, the radial pulse suddenly becomes undetectable. The lungs are clear to auscultation, and no wheezes are heard. Which of the following is the most likely diagnosis?

A 62-year-old woman comes to the physician complaining of a “gritty” sensation in the eyes for the last several months. She states her eyes have also been increasingly itchy and red, and she also needs to chew food for a longer period of time in order to swallow it properly. Past medical history is significant for rheumatoid arthritis that is well managed with methotrexate. Vital signs are within normal limits. Physical examination shows redness of both eyes. Bilateral wrist and first metacarpophalangeal joints show mild swelling and tenderness. There is nontender, diffuse parotid gland enlargement bilaterally. Oral examination reveals mucosal atrophy and multiple dental caries. Ophthalmologic examination reveals decreased visual acuity in both eyes. A strip of litmus filter paper is folded at one end and inserted in the patient’s lower eyelid; after 5 minutes, there is < 5 mm (normal > 15 mm) of moisture on the filter paper. Multiple corneal punctate spots are noted on fluorescein staining. Labial salivary gland biopsy would most likely show which of the following findings?

A 45-year-old man is admitted to the medical intensive care unit from the emergency department after having severe vomiting, diarrhea, and developing a rash. He recently returned from visiting family in Sierra Leone for several weeks to assist the embalming and burial of several family members. During the hospitalization he begins bleeding briskly from the nose, gums and several IV sites. His temperature is 38.1°C (100.6°F), pulse is 95/min, respirations are 18/min, and blood pressure is 100/60 mm Hg. Laboratories studies show:

Leukocyte count 10,500/mm3
Hemoglobin 9.2 g/dL
Platelet count 41,000/mm3
Creatinine 2.8 mg/dL
Alanine aminotransferase 1,120 U/L
Aspartate aminotransferase 1,250 U/L
D-dimer 5.5 mcg/mL

Which of the following causative agents is most likely responsible for the findings in this patient?

A 13-year-old boy presents to the pediatrician for a well-child visit and raises a concern for recent voice changes. The patient has noticed a deepening and hoarseness of his voice over the past eight weeks and is worried “something is wrong with my voice box.” His parent reports the patient has been sleeping 10-12 hours per day and had a “head-cold” two months ago. The patient is otherwise healthy and does not take any medications. He does not smoke, use illicit drugs, or consume alcohol. Vital signs are within normal limits. Physical examination demonstrates a tall, thin male in no acute distress with comedonal acne noted on the face. The patient’s posterior oropharynx is without evidence of edema, exudates, or erythema. There is no tenderness to palpation of the trachea. When asked to speak, the patient’s voice intermittently enters higher frequency registers. Which of the following is the most likely etiology of this patient’s clinical presentation?