Pathology Review for USMLE

Questions 180-184: Cardiovascular pathology

Question 180

A 53-year-old male with a past medical history of hypertension for 15 years presents to the emergency room with complaints of a sharp tearing pain in his chest that radiates to his back. His admission blood pressure in the right arm is 171/100 mmHg and in the left arm is 137/80 mmHg. A chest x-ray reveals a widened mediastinum. Of the following, what is the most likely diagnosis?

A. Acute myocardial infarct with free wall rupture
B. Unstable angina
C. Hypertensive crisis
D. Aortic dissection
E. Pheochromocytoma

Answer for Question 180

Answer: D (Aortic dissection)

Explanation: The clinical scenario is characteristic for an aortic dissection, which often occurs in older males and is associated with hypertension as the main underlying risk factor. The pain is often described as sharp or tearing and can radiate to the back. Depending upon the location of the dissection in the arch, the left subclavian artery and not the right subclavian artery can be involved, leading to asymmetric pulses. Because there is blood in the wall of the aorta, the mediastinum can be widened on chest x-ray.

Question 181

A 55-year-old male with a past medical history of poorly controlled hypertension for 10 years presents to the emergency room with complaints of a sharp tearing pain in his chest that radiates to his back. His admission blood pressure in the right arm is 165/98 mmHg and in the left arm is 134/81 mmHg. A chest x-ray reveals a widened mediastinum. Of the following, histologic examination of the aorta would most likely reveal?

A. Extensive neutrophilic infiltration
B. Extensive granulomatous infiltration
C. Marked hemosiderin deposition
D. Marked lipofuscin deposition
E. Cystic medial degeneration

Answer for Question 181

Answer: E (Cystic medial degeneration)

Explanation: The clinical scenario is consistent with an aortic dissection, which is associated with hypertension as the main underlying risk factor. The pain is often described as sharp or tearing and can radiate to the back. Depending upon the location of the dissection in the arch, the left subclavian artery and not the right subclavian artery can be involved, leading to asymmetric pulses. Because there is blood in the wall of the aorta, the mediastinum can be widened on chest x-ray. Histologic examination of the aorta often reveals cystic medial degeneration. Neither marked hemosiderin deposition nor marked lipofuscin deposition normally occur in the aorta. While either Takayasu or giant cell arteritis can involve the aorta and would be associated with a granulomatous inflammation, neither is usually associated with a dissection, and both would be rare compared to an aortic dissection.

Question 182

A 63-year-old male with a known history of well-controlled hypertension that has been treated for 20 years dies in a motor vehicle accident after another driver runs a red light and strikes his vehicle. At the autopsy, which of the following pathologic findings is most likely to be identified by the pathologist?

A. Coarctation of the aorta
B. A nodule in the adrenal medulla
C. Retinal hemorrhages and papilledema
D. A pale eosinophilic acellular thickening of arterioles
E. A layered cellular proliferation of the wall of arterioles

Answer for Question 182

Answer: D (A pale eosinophilic acellular thickening of arterioles)

Explanation: The histologic change most frequently associated with essential hypertension is hyaline arteriolosclerosis, which can be described as a pale eosinophilic acellular thickening of the arterioles, due to accumulation of plasma proteins within the wall. Retinal hemorrhage and papilledema, and a layered cellular proliferation of the wall of arterioles (i.e., hyperplastic arteriolosclerosis) are associated with malignant hypertension, which the clinical scenario does not fit, as malignant hypertension follows a rapid course, whereas a 20 year history is best consistent with essential hypertension. While coarctation of the aorta and a pheochromocytoma (i.e., the nodule in the adrenal medulla) cause hypertension, secondary hypertension is much less common than essential hypertension; also, conditions causing secondary hypertension are often diagnosed because the hypertension does not respond to medical treatment.

Question 183

A 52-year-old male presents to the emergency room with a history of chest pain that began 2 hours ago. The pain has been unrelenting, and is associated with shortness of breath and nausea. Laboratory testing reveals an elevated troponin I and EKG reveals ST elevation in leads V3-V6. The pathologic process that was the cause of his symptoms originated in which of the following types of blood vessels?

A. Elastic
B. Muscular
C. Small arteries
D. Arterioles
E. Capillaries

Answer for Question 183

Answer: B (Muscular)

Explanation: The clinical scenario is consistent with an acute myocardial infarct. The most common cause of a myocardial infarct is atherosclerosis of the coronary arteries. The coronary arteries are a form of muscular artery.

Question 184

A 43-year-old male presents to the hospital with complaints of shortness of breath that has developed increasingly over the past year. Physical examination reveals bilateral crackles at the base of both lungs, but no murmurs or rubs. A chest x-ray reveals a bilateral pleural effusion at the lung bases. Laboratory testing reveals an elevated concentration of B-type natriuretic peptide. A CT scan of his trunk and head reveals a 3.5 cm mass at the left cerebral convexity. Surgical resection of the mass reveals it to be composed of an admixture of arteries and veins. Of the following, what was the mechanism for his presenting symptoms?

A. Cardiac metastases
B. Constrictive pericarditis
C. Focal bypass of capillaries
D. Childhood infection resulting in cardiac damage
E. Hypertensive due to increased intracranial pressure

Answer for Question 184

Answer: C (Focal bypass of capillaries)

Explanation: The clinical scenario is consistent with congestive heart failure, with relatively slow onset of dyspnea, bilateral pleural effusions, and an elevated BNP. The mass in the head is an arteriovenous malformation. In an arteriovenous malformation, there is an abnormal connection between arteries and veins, bypassing the capillaries. Blood flowing through the mass therefore does not serve to oxygenate tissue. The heart is doing extra work to pump this un-used blood, and it is possible for heart failure to develop (i.e., high output cardiac failure). The mass is benign, and not even a neoplasm, and so cardiac metastases would not occur. As there is no murmur, chronic rheumatic valvulitis is not very likely. With increased intracranial pressure, there should likely be symptoms such as headache, nausea, vomiting, and as the mass is a congenital malformation, it would not (without hemorrhaging) elicit increased intracranial pressure as the body has had enough time to adapt to its presence.

Questions 175-179: Lung pathology

Question 175

A 54-year-old male with a 5 year history of increasing shortness of breath presents to his family physician at his wife’s insistence for further testing. He has a 50 pack-year smoking history. Physical examination reveals a barrel chest, and auscultation of his chest reveals decreased breath sounds and occasional wheezes, but no crackles. A chest x-ray reveals a flattened diaphragm and increase lucency of the lung fields. Which of the following mechanisms played the greatest role in the primary development of his disease process?

A. Protease-anti-protease imbalance
B. Recurrent infections
C. Airway hypersensitivity to nicotine
D. Allergen enhancement of tissue fibrosis
E. Neoplastic infiltration of pulmonary parenchyma

Answer for Question 175

Answer: A (Protease-anti-protease imbalance).

Explanation: The history (54-year-old male with a >40 pack-year smoking history presenting with chronic dyspnea), physical examination (barrel chest, decreased breath sounds and wheezing), and x-ray (flattened diaphragm and increased lucency of the lung fields) are consistent with emphysema. Oxidative stress, inflammation, and an imbalance of proteases-anti-proteases are the three main mechanisms by which emphysema develops. Individuals with emphysema are at increased risk for pneumonia, and pneumonia contributes to exacerbations of the disease, but are not as important in the primary development of the disease process as is the protease-anti-protease imbalance. Airway hypersensitivity, important in asthma, is not important in the primary development of emphysema. Fibrosis is not a significant component of emphysema and neoplastic proliferation would more likely present as a restrictive lung disease, or, bronchiectasis, if there was airway obstruction, but is not the primary mechanism for the development of emphysema.

Question 176

A 35-year-old male with a 2 year history of increasing shortness of breath presents to his family physician for evaluation. He has a 15 pack-year smoking history. Auscultation of his chest reveals decreased breath sounds and occasional crackles. Pulmonary function testing reveals a decreased FEV1/FVC ratio. Of the following, which set of parameters best describes his disease process involvement of the lungs?

Answer for Question 176

Answer: D (Panacinar and lower lobes)

Explanation: The clinical presentation (chronic dyspnea associated with decreased breath sounds and occasional crackles) combined with the PFTs (decreased FEV1/FVC ratio) is consistent with emphysema. Given his young age and mild smoking history, he most likely has α1-antitrypsin deficiency, which causes panacinar emphysema and affects more commonly the lower lobes, whereas emphysema due to smoking causes centriacinar emphysema and affects the upper lobes.

Question 177

A 32-year-old male with a 1 year history of increasing shortness of breath presents to his family physician for evaluation. He has a 10 pack-year smoking history. Auscultation of his chest reveals decreased breath sounds and occasional crackles. Pulmonary function testing reveals a decreased FEV1/FVC ratio. Of the following conditions, which is this patient at greatest risk for?

A. Early-onset degenerative aortic stenosis
B. Amyloidosis of the heart
C. Adenocarcinoma of the gallbladder
D. Hepatocellular carcinoma
E. Glioblastoma multiforme

Answer for Question 177

Answer: D (Hepatocellular carcinoma)

Explanation: The clinical presentation (chronic dyspnea associated with decreased breath sounds and occasional crackles) combined with the PFTs (decreased FEV1/FVC ratio) is consistent with emphysema. Given his young age and mild smoking history, he most likely has α1-antitrypsin deficiency. Patients with α1-antitrypsin deficiency are at risk for emphysema and, often, cirrhosis of the liver. Individuals with cirrhosis of the liver are at risk for the development of hepatocellular carcinoma. α1-antitrypsin deficiency is not commonly associated with the other conditions listed.

Question 178

A 19-year-old female college student is being seen in the emergency room for an episode of severe dyspnea. In the last 5 years, she has had to go to the emergency room 4 times for a similar episode. Vital signs include blood pressure of 123/80 mmHg, heart rate of 112 bpm, and respiratory rate of 30 bpm. During inspiration, her systolic blood pressure decreases by 15 mmHg. Physical examination reveals her to be in acute distress. Auscultation of the chest reveals wheezes. The underlying mechanism of her disease process is which of the following?

A. Type I hypersensitivity reaction
B. Type II hypersensitivity reaction
C. Type III hypersensitivity reaction
D. Type IV hypersensitivity reaction

Answer for Question 178

Answer: A (Type I hypersensitivity reaction)

Explanation: The clinical presentation (acute onset of severe dyspnea in a young adult, with history of previous such episodes in the past, and with wheezing, tachypnea, tachycardia, and pulsus paradoxus (the decrease in systolic blood pressure with inspiration) is consistent with asthma. The underlying mechanism of asthma is a type I hypersensitivity reaction.

Question 179

A 13-year-old female is brought to the emergency room by her parents as she has developed severe dyspnea, and they can see her using the muscles in her neck to help her breath. Her mother has a history of developing a rash after working outside on occasions. Her vital signs include blood pressure of 119/78 mmHg, heart rate of 115 bpm, and respiratory rate of 32 bpm. During inspiration, her systolic blood pressure decreases by 16 mmHg. Physical examination reveals her to be in acute distress. Auscultation of the chest reveals wheezes. Of the following, which histologic change is most likely present in the lungs?

A. Loss of pulmonary parenchyma
B. Numerous granulomas
C. Infiltrates of neutrophils
D. Infiltrates of plasma cells
E. Infiltrates of eosinophils

Answer for Question 179

Answer: E (Infiltrates of eosinophils)

Explanation: The clinical presentation (acute onset of severe dyspnea in child, and with wheezing, tachypnea, tachycardia, and pulsus paradoxus) is consistent with asthma. Histologic changes in asthma include hypertrophy of the smooth muscle of the airways, sub-basement membrane fibrosis making the basement membrane appear thick, mucous gland hyperplasia, and infiltrates of eosinophils. Curschmann spirals (mucous casts of the airways with shed epithelium) and Charcot-Leyden crystals can also be identified. Given that this is her first presentation, the other histologic features of asthma would probably not be well-developed.

Questions 171-174: Lung pathology

Question 171

A 31-year-old male is brought to the emergency room by friends because of his difficulty breathing. About 18 hours before his presentation to the emergency room, they reported he had been exposed to a benzene spill at his place of work. While he felt fine after the accident, his current symptoms have developed rapidly over the past 2 hours. Of the following, what is the most likely primary mechanism for his clinical presentation?

A. Insufficient amount of surfactant
B. Necrosis of alveolar epithelial cells
C. Tumor embolism
D. Delayed allergic reaction to the chemical exposure
E. Rapid overgrowth of bacteria

Answer for Question 171

Answer: B (Necrosis of alveolar epithelial cells)

Explanation: Given his rapid onset of shortness of breath within 1 day from a pulmonary chemical exposure, he most likely has acute respiratory distress syndrome (ARDS). Acute respiratory distress syndrome develops due to damage to the alveolar epithelial and/or endothelial cells, which result in leakage of protein-rich fluid into the alveolar airspaces and the resultant formation of hyaline membranes. While a loss of surfactant can occur during the process of ARDS it is not the primary mechanism for the clinical presentation. In hyaline membrane disease in premature infants, a deficiency of surfactant is the primary mechanism for the clinical presentation. While tumor embolism, a delayed allergic reaction to the chemical exposure, or a rapid overgrowth of bacteria could each have the potential for a rapid onset pulmonary-centered clinical process, each of these would be rare compared to the likelihood of ARDS in the above clinical scenario.

Question 172

A 25-year-old male has had a fever and cough productive of a thick yellow-green sputum for one week. He reports occasional sharp chest pain associated with the cough or breathing. Although he felt he had a cold that he could shake, he is now presenting to the emergency room, as over the past 2 hours, he has developed rapidly increasing shortness of breath. His vital signs are blood pressure of 142/83 mmHg, heart rate of 112 bpm, and respiratory rate of 30 bpm. Physical examination reveals no friction rub and the heart sounds do not sound distant. Of the following, which radiographic finding, if not already present, should develop shortly?

A. Bilateral opacities
B. A wedge-shaped opacity in the right lower lobe
C. A widened mediastinum
D. An enlarged cardiac silhouette
E. Diffuse consolidation of the entire lower lobe of the left lung

Answer for Question 172

Answer: A (Bilateral opacities)

Explanation: The patient most likely had a bacterial pneumonia for one week, which could produce fever, a productive cough, and pleuritic chest pain. However, given his rapid change, resulting in progressive dyspnea, tachypnea and tachycardia, he has most likely developed acute respiratory distress syndrome (ARDS). One of the most common causes of ARDS is pneumonia. The characteristic x-ray finding would be bilateral opacities (due to filling of the alveolar airspaces with a mixture of inflammatory cells, and protein-rich edema fluid). ARDS is a diffuse disease process, and thus, the x-ray findings are typically bilateral. A wedged-shaped opacity in the right lower lobe could indicate an infarct due to a pulmonary thromboembolus, which can also present with acute respiratory insufficiency and patients can have a pleuritic chest pain, but he has no risk factors described for a pulmonary thromboembolus (e.g., immobility). A widened mediastinum is consistent with an aortic dissection, and the patient is not described to have hypertension, and the clinical presentation in the week prior is not characteristic for an aortic dissection. An enlarged cardiac silhouette would indicate cardiac hypertrophy or a tamponade. While acute pericarditis can occur in association with pneumonia and could present with increasing shortness of breath, the absence of friction rub and non-distant heart sounds do not support what would already be a relatively rare complication of pneumonia. A diffuse consolidation of the entire lobe of the left lung is consistent with a lobar pneumonia, which he most likely has; however, it would not fully explain the sudden change in clinical status.

Question 173

A 71-year-old male with a 10 year history of Alzheimer’s disease is identified by nursing home staff to have labored breathing. He is taken to the emergency room where a physical examination reveals a blood pressure of 138/81 mmHg, respiratory rate of 29 bpm, and heart rate of 109 bpm. He is admitted to the hospital. Over the next 6 hours, his condition worsens with increasing shortness of breath, and he develops bilateral rales. A chest x-ray reveals bilateral opacities in the pulmonary parenchyma throughout. He has no friction rub, and no S3 or S4 are heard on auscultation of the heart. Microscopic examination of this lungs would reveal which of the following?

A. Proteinaceous exudates layered on the alveolar septa
B. Extensive lymphatic tumor micro-emboli
C. Innumerable microscopic venous thrombi
D. Extensive eosinophilic infiltrates
E. Extensive plasma cell infiltrates

Answer for Question 173

Answer: A (Proteinaceous exudates layered on the alveolar septa)

Explanation: Given the sudden change in his clinical status with rapidly increasing dyspnea associated with tachypnea and tachycardia, acute respiratory distress syndrome (ARDS) is a good possibility. Aspiration is a common cause of ARDS and can easily occur in a patient with long-standing Alzheimer disease. The bilateral opacities are also characteristic of ARDS, which would have been the cause of the rales. Congestive heart failure is in the differential diagnosis for ARDS, and with CHF patients would often have an S3. The characteristic histologic feature of ARDS is hyaline membranes, which are proteinaceous exudates layered on the alveolar septa. While all of the other choices could cause an acute respiratory decline, each would be rare compared to ARDS in the background of aspiration.

Question 174

A 59-year-old male with a 3 year history of increasing shortness of breath presents to his family physician for further testing. He has a 45 pack-year smoking history. The dyspnea is not accompanied by chest pain. He also reports that he frequently coughs up thick sputum, often for months at a time over the past three years. Auscultation of his chest reveals decreased breath sounds and occasional wheezes and crackles. Of the following, which set of parameters is most consistent with his disease process?

Answer for Question 174

Answer: C (Increased TLC (total lung capacity), severely decreased FEV1 (forced expiratory volume), decreased FVC (forced vital capacity), and increased RV (residual volume)).

Explanation: In an older male with a >40 pack-year smoking history, who presents with chronic dyspnea associated with a chronic productive cough, and who has decreased breath sounds on physical examination and occasional wheezes and crackles, the most likely diagnosis is chronic obstructive pulmonary disease. In individuals with COPD, the FEV1 is severely decreased, and the residual volume is increased – the disease process is obstructive, so air cannot be exhaled, and air is trapped. The FVC is usually normal or decreased, and the total lung capacity can be increased, decreased or normal. Importantly, the FEV1/FVC ratio is decreased; in restrictive lung disease, the residual and TLC are decreased and the FEV1/FVC ratio is normal or increased.

Questions 166-170: Lung pathology

Question 166

A 62-year-old male non-smoker has been referred to a pulmonologist by his primary care physician for recurring respiratory infections. Over the past two years he has gradually gotten more short of breath with activity, and has a chronic non-productive cough. He has lost about 5 lb. in that time, but reports no night sweats. Despite several antibiotic courses, he has never gotten better. Physical examination reveals clubbing of the fingers and bi-basilar crackles. X-ray reveals a reticular pattern at the bases, but no effusion. Pulmonary function testing reveals a FEV1/FVC ratio of 81% and a reduced total lung capacity. Of the following, what is the most likely diagnosis?

A. Idiopathic pulmonary fibrosis
B. Congestive heart failure due to untreated systemic hypertension
C. Mycobacterium tuberculosis
D. Small cell carcinoma of the lung
E. Recurrent Staphylococcus aureus pneumonia

Answer for Question 166

Answer: A (Idiopathic pulmonary fibrosis)

Explanation: The slow onset of shortness of breath and the non-productive cough in an older individual is consistent with the clinical presentation of idiopathic pulmonary fibrosis, which can be misdiagnosed as infection or heart failure. Clubbing of the fingers and bi-basilar crackles are features of the disease process. The reticular pattern is consistent with the diagnosis, and the absence of effusions makes congestive heart failure unlikely. The pulmonary function tests are consistent with a restrictive lung disease, of which small cell carcinoma is not. While fibrosis associated with a mycobacterium tuberculosis infection or recurring Staphylococcus aureus pneumonia could possibly produce a restrictive lung disease, no other information supports either of these diagnoses (e.g., history of tuberculosis exposure, homelessness, etc.), or evidence of an infection (such as fever, productive cough, etc.).

Question 167

A 46-year-old male presents to his family physician indicating that over the past 2 years he has had increasing shortness of breath associated with a non-productive cough and 20 lb. weight loss. He has not traveled outside of his home state of Montana; however, his main hobby is using carrier pigeons to send messages. Physical examination reveals bilateral fine crackles and clubbing of the fingers. Of the following, what is the most likely diagnosis?

A. Acute hypersensitivity pneumonitis
B. Chronic hypersensitivity pneumonitis
C. Usual interstitial pneumonia
D. Congestive heart failure
E. Aortic stenosis due to calcified bicuspid aortic valve

Answer for Question 167

Answer: B (Chronic hypersensitivity pneumonitis)

Explanation: The presenting (slow onset of dyspnea associated with a cough and weight loss) is consistent with a chronic disease and with interstitial lung disease. The physical examination, with bibasilar fine crackles and clubbing, is also consistent with interstitial lung disease. Given the history of using pigeons, chronic hypersensitivity pneumonitis is the best choice. Usual interstitial pneumonia occurs more commonly in older patients and is not associated with pigeons, and while congestive heart failure, or end stage of aortic stenosis with congestive heart failure, could have crackles and clubbing, nothing else in the question scenario supports these two diagnoses, such as a murmur heard on physical examination, or history of orthopnea or paroxysmal nocturnal dyspnea.

Question 168

A 49-year-old male with a history of chronic sinusitis that has been relatively refractory to medical treatment is brought to the emergency room by his wife because he has been coughing up a large amount of blood for the past two hours. In the week prior, he had developed cough, pain in his chest with breathing, and some shortness of breath. Assuming it was a bad cold, he wanted to wait it out, but the blood scared his wife. A chest x-ray reveals several areas of consolidation and a urinalysis reveals blood. Of the following, which is the most likely diagnosis?

A. Necrotic squamous cell carcinoma
B. Granulomatosis with polyangiitis
C. Disseminated Mycobacterium tuberculosis
D. Sudden onset congestive heart failure with massive hemoptysis
E. Pneumocystis jirovecki infection

Answer for Question 168

Answer: B (Granulomatosis with polyangiitis)

Explanation: Involvement of the upper and lower respiratory tract (i.e., the chronic sinusitis and the consolidation of the lungs) and the kidney (the blood in the urine) are consistent with granulomatosis with polyangiitis, which occurs in individuals around this age. They can develop diffuse alveolar hemorrhage, which would explain the hemoptysis. Given his younger age and the lack of smoking history and the renal involvement, a necrotic squamous cell carcinoma is not likely. With no information to suggest immunosuppression, Pneumocystis is not likely. While tuberculosis can present with massive hemoptysis, he has no risk factors. Congestive heart failure is not commonly associated with massive hemoptysis and is normally a chronic process, and he has no history or other information to support this diagnosis.

Question 169

A 47-year-old male is brought to the emergency room by his wife because over the past two weeks he has had a bad cough, some shortness of breath, and pain with breathing. A chest x-ray was performed, revealing areas of consolidation and antibiotics were prescribed; however, he has not gotten better. He has no significant past medical history other than general malaise over the preceding year. Laboratory testing is performed including ANCA testing. MPO-ANCA is identified. A urinalysis reveals blood. Of the following, what is the most likely diagnosis?

A. Granulomatosis with polyangiitis
B. Polyarteritis nodosa
C. Microscopic polyangiitis
D. Kawasaki disease
E. Giant cell arteritis

Answer for Question 169

Answer: C (Microscopic polyangiitis)

Explanation: Polyarteritis nodosa rarely involves the lungs and is not normally associated with ANCA positivity. Kawasaki disease primarily involves the heart, and is most commonly a disease of children. Giant cell arteritis most commonly involves the aorta and branches; so, none of these three diagnoses is a good choice. The presentation of granulomatosis with polyangiitis and microscopic polyangiitis can be very similar, and both can have MPO-ANCA; however, MPO-ANCA is most commonly associated with microscopic polyangiitis and not granulomatosis with polyangiitis.

Question 170

A 23-year-old male is stabbed by another person in the chest. He is responsive when EMTs arrive, but is short of breath. His heart rate is 115 bpm. During the trip to the emergency room, his shortness of breath worsens; he develops hypotension; and he ultimately becomes unresponsive. Despite resuscitative efforts, he dies. An autopsy is performed. The right pleural cavity contains a measured 2 L of blood, which originated from an intercostal artery in the path of the stab wound. Microscopic examination of the right lung would reveal which of the following?

A. Extensive eosinophilic infiltrates
B. Patchy neutrophilic infiltrates
C. Collapse of alveoli
D. Numerous fat emboli
E. Foreign body embolus composed of the tip of the knife

Answer for Question 170

Answer: C (Collapse of alveoli)

Explanation: The rapid accumulation of a large amount of fluid (i.e., blood) in the right pleural cavity would compress the lung, and not allow it to fill as normal with air (i.e., compression atelectasis). The time frame is too short for an acute pneumonia to be developing and extensive eosinophilic infiltrates would not be the normal response. Fat emboli occur as the result of bony trauma, usually of the long bones, and would not cause the blood to accumulate. Embolism of the knife tip would be exceptionally rare, and, since the artery was cut and not the vein, if the knife tip entered the blood supply, it would not be going to the heart.

Questions 162-165: Lung pathology

Question 162

A 62-year-old male who has not seen a doctor in 20 years presents to a family physician at his wife’s insistence. Over the last 4 months he has had a chronic cough, occasional pain in his chest, and 20 lb. of weight loss. A chest x-ray reveals a mass in the upper lobe of the left lung. Biopsy reveals neoplastic squamous cells. Of the following, what was the most likely etiology of his neoplasm?

A. Cigarette smoke
B. Asbestos exposure
C. Radon exposure
D. Arsenic exposure
E. Past contact with radioactive substance

Answer for Question 162

Answer: A (Cigarette smoke)

Explanation: All of the above exposures (i.e., cigarette smoke, asbestos, radon, arsenic, and radiation) are risk factors for lung carcinoma; however, the most common etiology of lung cancer is cigarette smoke.

Question 163

A 62-year-old male with a 45 pack year smoking history undergoes chest x-ray as a component of a pre-surgical evaluation for elective cholecystectomy. The x-ray reveals a mass in the lower lobe of the left lung. Laboratory testing reveals an ionized calcium concentration of 6.7 mg/dL (normal range: 4.56-5.40 mg/dL). A biopsy of the mass would most likely reveal which of the following?

A. Benign cartilage
B. Epithelial cells with intercellular bridges
C. Caseating granulomas
D. Mass of neutrophils admixed with bacterial cocci
E. Mass of abnormally connected arteries and veins

Answer for Question 163

Answer: B (Epithelial cells with intercellular bridges)

Explanation: Given the history of smoking and the fact that lung cancer is often asymptomatic, the finding of an incidental mass on chest x-ray is concerning for a neoplasm. Squamous cell carcinoma produces PTH-related peptide, which can cause an elevated concentration of calcium. The features of squamous cell carcinoma include intercellular bridges and keratin pearls. A pulmonary hamartoma (benign cartilage) would not cause hypercalcemia. Although sarcoidosis can produce elevated concentrations of calcium and is often found in the lung, most sarcoidosis granulomas are non-caseating. Neither an abscess (i.e., a mass of neutrophils admixed with bacterial cocci) or an arteriovenous malformation (i.e., a mass of abnormally connected arteries and veins) are commonly associated with elevated concentrations of calcium, and he has no fever, or other symptoms indicative of an infection.

Question 164

A 65-year-old male with a history of hypertension, diabetes mellitus type II, and a 45 pack-year smoking history with chronic cough presents to an acute care clinic with complaints that he has gotten very sensitive to heat lately and cannot tolerate working outside in his garden for very long. Physical examination reveals drooping of his left upper eyelid and constriction of the left pupil compared to the right side. In addition, the left eye appears somewhat sunken in the orbit. Of the following, which procedure is most likely to identify the cause of his condition?

A. CT scan of the head
B. X-ray of the chest
C. Echocardiogram
D. Lumbar puncture
E. MRI of the pelvis

Answer for Question 164

Answer: B (X-ray of the chest)

Explanation: The patient has features of Horner syndrome (enophthalmos – the sunken nature of the eye; ptosis – the drooping of the upper eyelid; miosis – constriction of the pupil; and the heat intolerance is a symptom of anhidrosis, which is lack of sweating). Given his age and smoking history, a lung neoplasm at the apex of the lung (i.e., a Pancoast tumor) would be a strong possible cause. Of the choices, an x-ray of the chest would be most likely to reveal the tumor.

Question 165

A 54-year-old male with a past medical history of hypertension and a 40 pack-year smoking history is undergoing a routine physical examination prior to a scheduled inguinal hernia repair. Physical examination reveals a small fixed palpable node above the left clavicle. A fine needle aspirate of this node reveals small cells with a high nuclear:cytoplasm ratio and high mitotic rate. No glandular formation or keratin production is evident. Molecular analysis of the cells would most likely reveal which of the following genetic abnormalities?

A. RB mutation
B. EGFR mutation
C. ALK rearrangement
D. p16/CDKN2A mutation
E. PTEN mutation

Answer for Question 165

Answer: A (RB mutation)

Explanation: Given the age of the patient and smoking history, he is at risk for lung cancer. A palpable supraclavicular node (i.e., Virchow node) is characteristic for metastatic spread of a lung carcinoma. The cellular features are indicative of a small cell carcinoma, and the neoplasm has no features of either adenocarcinoma or squamous cell carcinoma. Over 90% of small cell carcinomas have a mutation of RB. EGFR mutations and ALK rearrangements are characteristic of adenocarcinomas, and p16/CDKN2A are very uncommonly found in small cell carcinoma and are more characteristic of non-small cell carcinoma. PTEN mutation is commonly associated with endometrial carcinoma and melanoma; however, it is uncommonly (6-9%) associated with lung carcinoma, and predominantly with squamous cell carcinoma.

Questions 159-161: Lung pathology

Question 159

A 32-year-old male presents to an acute care clinic with complaints of chest pain that is worse when he breathes in. The chest pain started about a day ago. A few hours ago he coughed up blood. Physical examination reveals some dullness to percussion in the left upper lobe and crackles are heard at that site. His only past medical history is that he broke his left tibia one week ago while skiing, and has had to wear a cast, which he reports has hindered his ability to get around like normal. Of the following, which laboratory test is most likely to be elevated?

A. D-Dimer
B. PTT
C. AST
D. Hct
E. Glucose

Answer for Question 159

Answer: A (D-dimer)

Explanation: The clinical scenario is consistent with a pulmonary thromboembolus, which can present with pleuritic chest pain and hemoptysis. A peripheral thromboembolus can produce an infarction of the lung, which would lead to the dullness to percussion and crackles. The immobility is a risk factor for deep venous thrombosis and resultant pulmonary thromboembolus. Of the laboratory tests listed, an elevated d-dimer is most associated with deep venous thrombi and a pulmonary thromboembolus. In a patient with anti-phospholipid antibody syndrome, an elevated PTT would be possible, and those patients are at risk for thrombi and embolism; however, the history does not otherwise suggest this condition, and it is only one of many conditions that could possibly predipose to thrombosis and embolism.

Question 160

A 23-year-old tall and thin male presents to the emergency room at 2 am, saying that he awoke due to a sudden pain in his chest that was worse when he breathed, and has had difficulty breathing since that time. Physical examination reveals hyperresonance to percussion on the left side of his chest, which is associated with decreased breath sounds and absence of tactile fremitus. Of the following, what is the most likely diagnosis?

A. Acute myocardial infarct
B. Aortic dissection associated with Marfan syndrome
C. Pneumothorax
D. Lobar pneumonia
E. Pulmonary thromboembolus

Answer for Question 160

Answer: C (Pneumothorax)

Explanation: The clinical presentation is classic for a spontaneous pneumothorax (tall thin young male with sudden onset pleuritic chest pain and dyspnea). Physical examination is likewise consistent with pneumothorax – the hyperresonance occurs because the pleural cavity is filled with air, as do the decreased breath sounds and absence of tactile fremitus, since the lung is displaced away from the chest wall by intervening air. Although tall and thin suggest Marfan syndrome, the physical examination is not consistent with an aortic dissection and hemothorax (especially the hyperresonance); also, the patient would be potentially in shock from blood loss if an aortic dissection were the cause of his symptoms. The physical examination is also not consistent with pulmonary thromboembolus, although the sudden onset of dyspnea and pleuritic chest pain could be consistent.

Question 161

A 16-year-old tall male is playing basketball with friends when he suddenly develops chest pain and shortness of breath. His friends take him to the emergency room where a physical examination reveals hyperresonance to percussion on the left side of his chest, which is associated with decreased breath sounds and absence of tactile fremitus. Of the following, what is the most likely underlying pathologic finding?

A. Ruptured pulmonary bleb
B. Inflammation of blood vessel
C. Tearing of large caliber blood vessel
D. Asymmetric thickening of myocardium
E. Thrombus in blood vessel

Answer for Question 161

Answer: A (Ruptured pulmonary bleb)

Explanation: The clinical presentation is classic for a spontaneous pneumothorax (tall young male with sudden onset chest pain and dyspnea). Physical examination is likewise consistent with pneumothorax – the hyperresonance occurs because the pleural cavity is filled with air, and the decreased breath sounds and absence of tactile fremitus, since the lung is displaced away from the chest wall by intervening air. Although tall and thin suggest Marfan syndrome, the physical examination is not consistent with an aortic dissection and hemothorax (especially the hyperresonance), and thus a tearing of large caliber blood vessel is not the finding; also, the patient would be potentially in shock from blood loss. Although patients with hypertrophic cardiomyopathy can present as sudden death, the history and physical examination findings are not consistent with the diagnosis (i.e., a patient with hypertrophic cardiomyopathy would not normally developed sudden chest pain and shortness of breath). The physical examination findings are not consistent with a vasculitis or pulmonary thromboembolus.

Questions 156-158: Lung pathology

Question 156

A 29-year-old male presents to an acute care clinic with complaints of a productive cough and fever to 38.7 degrees Celsius for the past 3 days, associated with some chest pain when he breaths and with chills. Physical examination reveals dullness to percussion on the left side of the chest. Crackles and a pleural rub are also heard at this location. A chest x-ray reveals consolidation of the left lung. A sputum culture is obtained and grows a pure sample of gram positive cocci in chains. Of the following, laboratory testing of this organism would reveal which of the following traits?

A. Not inhibited by optochin
B. Beta hemolytic
C. Bile soluble
D. Non-fermenter of glucose
E. Catalase positive

Answer for Question 156

Answer: C (Bile soluble)

Explanation: The presenting features are consistent with a community acquired pneumonia, consistent with a lobar pneumonia. A common cause of a lobar pneumonia is Streptococcus pneumoniae, which is gram positive and grows in chains. Streptococcus pneumoniae is bile soluble. It is also inhibited by optochin, alpha hemolytic, a fermenter of glucose, and catalase negative.

Question 157

Following a four day illness that was characterized by a high fever (up to 41 degrees Celsius) and severe muscle aches, a 29-year-old male presents to the emergency room with complaints of dyspnea with exertion, chest pain which is worse with expiration, and a productive cough. Physical examination reveals dullness to percussion on the left side of the chest. Crackles and a pleural rub are also heard at this location. A chest x-ray reveals consolidation of the left lung. A sputum culture is obtained and grows a pure sample of gram positive cocci in clusters. Of the following, laboratory testing of this organism would reveal which of the following traits?

A. Catalase negative
B. Coagulase positive
C. Alpha hemolysis
D. Non-fermenter of glucose

Answer for Question 157

Answer: B (Coagulase positive)

Explanation: The preceding illness has features of influenza (high fever and myalgias). One complication of influenza is the subsequent development of a secondary bacterial infection. In this situation, the patient developed Staphylococcus aureus, which is a common etiologic agent of a secondary bacterial infection in patients with influenza. Staphylococcus aureus is coagulase positive. It is also catalase positive, beta hemolytic and a fermenter of glucose.

Question 158

A 73-year-old male with the history of a stroke 2 years ago that left him with residual motor difficulties in eating is brought to the emergency room by his family because over the past three weeks he had developed a productive cough with foul-smelling sputum. In addition, he has lost about 10 lb. and has an intermittent fever (although his temperature wasn’t taken). He has no history of tobacco use. A chest x-ray reveals an infiltrate in the lower lobe of the right lung. Of the following, what is the most likely diagnosis?

A. Community acquired bacterial pneumonia
B. Community acquired viral pneumonia
C. Aspiration pneumonia
D. Mycobacterium tuberculosis
E. Necrotic pulmonary neoplasm

Answer for Question 158

Answer: C (Aspiration pneumonia)

Explanation: Elderly individuals, especially those with a history of a condition that would cause neuromuscular impairment, such as a stroke, are at risk for aspiration pneumonia. Because aspiration pneumonia often involves anaerobic bacteria and/or abscess formation, the patient can produce foul-smelling sputum. With aspiration pneumonia, patients often present over weeks or months and can have fever and weight loss. The lower lobes are affected, and more often the right side than the left side as the angle of the right bronchus allows for aspirated material to more easily enter the right lung.

Questions 153-155: Lung pathology

Question 153

A 29-year-old female presents to an acute care clinic with complaints of a productive cough and fever to 38.6 degrees Celsius for the past 4 days. Physical examination reveals dullness to percussion on the lower left side of the chest and crackles are heard at this location. A chest x-ray reveals consolidation of the lower lobe of the left lung. A sputum culture grows Streptococcus pneumoniae. Of the following, which is the most responsible for the physical examination findings?

A. Collapse of alveoli
B. Proteinaceous exudate on alveolar septae
C. Bacterial overgrowth
D. Lymphocytic infiltration of alveolar septae
E. Neutrophilic infiltration of alveolar airspaces

Answer for Question 153

Answer: E (Neutrophilic infiltration of alveolar airspaces)

Explanation: The presenting symptoms are consistent with a community-acquired pneumonia, and the physical examination and chest x-ray are consistent with a lobar pneumonia, which is most commonly caused by Streptococcus pneumoniae. Although atelectasis, hyaline membranes, and bacterial overgrowth could/would all be present to some degree, the cause for the consolidation of the lung tissue (i.e., the lung tissue having a more solid appearance) is due to the neutrophilic infiltrate in the alveolar airspaces, filling the airspaces in the lung. Lymphocytic infiltration of the alveolar septae would be characteristic of a viral infection.

Question 154

A 34-year-old male presents to an acute care clinic with complaints of a productive cough and fever to 38.4 degrees Celsius for the past 3 days, associated with shaking chills and some chest pain when he breaths. Physical examination reveals dullness to percussion on the left side of the chest. Crackles and a pleural rub are also heard at this location. A chest x-ray reveals consolidation of the left lung. Of the following, if untreated, which complication is he most likely to develop?

A. Bronchogenic carcinoma
B. Amyloidosis
C. Fibrosis in the left pleural cavity
D. Alzheimer disease
E. Aortic dissection

Answer for Question 154

Answer: C (Fibrosis in the left pleural cavity)

Explanation: Given the clinical presentation, a bacterial lobar pneumonia is likely. The pleural friction rub would indicate that there is pleuritis. With a bacterial infection causing pleuritis, complete resolution would be less likely, and scar formation would occur. Bacterial (and viral) pneumonias are not a significant risk factor for the other disease processes listed.

Question 155

A 26-year-old male presents to the hospital with complaints of difficulty breathing, which has severely worsened over the past day. In the five days prior, he has had a fever, productive cough, and chills. In addition, his chest has hurt when he breathed in and with exertion he was short of breath. His friends told him to come to the emergency room two days ago, but he thought that he could wait it out. He has a temperature of 101 degrees Fahrenheit, heart rate of 108 bpm, blood pressure of 105/71 mmHg, and respiratory rate of 28 breaths per minute. Physical examination reveals dullness to percussion on the left side of the chest, accompanied by decreased breath sounds, and an absence of tactile fremitus. Of the following, what is the most likely diagnosis?

A. Pulmonary thromboembolus
B. Congestive heart failure associated with bicuspid aortic valve
C. Tension pneumothorax due to ruptured bleb
D. Empyema
E. Aspiration pneumonia with abscess formation

Answer for Question 155

Answer: D (Empyema)

Explanation: The clinical presentation is consistent with a community acquired pneumonia. The dullness to percussion on the left side of the chest combined with the decreased breath sounds and absence of tactile fremitus are consistent with an empyema. While the pneumonia alone could cause the dullness to percussion associated with the consolidation of the lobe, there would not be decreased breath sounds, and there would be tactile fremitus. While a pulmonary thromboembolus could, with infarction, lead to dullness to percussion, it would not produce the other physical examination findings, and is not associated with a productive cough. Congestive heart failure due to a bicuspid aortic valve would present much later in life, and would not be associated with the productive cough The individual has no described risk factors for aspiration pneumonia.

Questions 150-152: Lung pathology

Question 150

A 27-year-old male, who is a college instructor, presents to an acute care clinic with complaints of a productive cough for 3 days, a fever, and occasional difficulty breathing with exertion. He has no significant past medical history and does not smoke. A chest x-ray reveals consolidation of the lower lobe of the right lung. Of the following, what is the most likely etiology for his clinical presentation?

A. Bacterial infection
B. Parasitic infection
C. Mycobacterial infection
D. Aspiration
E. Neoplasm

Answer for Question 150

Answer: A (Bacterial infection)

Explanation: The presentation (short duration of productive cough, fever, and dyspnea) in an individual with no past medical history and with consolidation of one lung lobe is consistent with a lobar pneumonia, which, in this situation, would be a community-acquired bacterial infection, or possibly a community acquired viral infection, which can also have consolidation of a lung lobe on x-ray. Lobar pneumonia is often bacterial in origin, and most commonly Streptococcus pneumoniae. Given his history, Mycobacterium tuberculosis is unlikely (i.e., he is not homeless, or otherwise living under conditions likely to expose him to tuberculosis). He has no risk factor for aspiration; and given his young age and lack of smoking history, a pulmonary neoplasm would be very unlikely.

Question 151

A 33-year-old female, who is a nurse at the hospital, presents to an acute care clinic with complaints of a productive cough for 2 days associated with shaking chills. She also reports a fever of 38.5 degrees Celsius. She has no significant past medical history and does not smoke. Her heart rate is 105 bpm, her respiratory rate is 26 breaths per minute, and her blood pressure is 82/61 mmHg, which is lower than normal for her. A chest x-ray reveals consolidation of the lower lobe of the left lung. A blood culture is positive. Of the following, which condition in her past medical history would represent the most important risk factor for her current presenting condition?

A. Fracture of the left tibia three years ago while skiing
B. Remote splenectomy after abdominal trauma
C. Head injury following rock climbing fall
D. Past episode of deep venous thrombosis
E. History of acute rheumatic fever

Answer for Question 151

Answer: B (Remote splenectomy after abdominal trauma)

Explanation: The presenting features (productive cough and fever) combined with the x-ray results are consistent with a community-acquired pneumonia, which would likely be a lobar pneumonia in this case. The most common bacterial etiologic agent for a lobar pneumonia is Streptococcus pneumoniae. Individuals without a spleen are at increased risk for the development of a pneumococcal sepsis as the spleen plays a role in the production of antibodies against polysaccharides, which protect against encapsulated organisms. The other conditions would be play a significant role in her development of pneumonia or resultant sepsis.

Question 152

A 24-year-old male who has smoked since he was 14 years old but has no other past medical history presents to an acute care clinic in July with complaints of a productive cough and fever to 38.4 degrees Celsius for the past 4 days. Physical examination reveals dullness to percussion on the lower left side of the chest and crackles are heard at this location. Of the following, what is the most likely diagnosis?

A. Community-acquired pneumonia
B. Chronic bronchitis
C. Pulmonary thromboembolus
D. Bronchogenic carcinoma
E. Aspiration pneumonia

Answer for Question 152

Answer: A (Community-acquired pneumonia)

Explanation: The presentation (cough and fever) and physical examination (dullness to percussion and crackles) are consistent with a community-acquired pneumonia. While chronic bronchitis can present with a productive cough, patients would normally be afebrile and there would be no localizing physical examination findings (i.e., the dullness to percussion or crackles). While a pulmonary thromboembolus could, with infarction, lead to a region of dullness to percussion and crackles, and could have a fever, the productive cough would not be typical and the patient has no risk factors for deep venous thrombi. Even though he has a smoking history, a bronchogenic carcinoma would be rare at this age. While aspiration pneumonia could cause the signs and symptoms listed, the patient has no risk factors for aspiration (e.g., a neuromuscular disease, or drug/alcohol intoxication).

Question 149: Hematopathology

Question 149

While on a 4th year elective rotation in Africa, a medical student sees a 1-year-old black female who was brought to the clinic by her parents. Physical examination reveals prominence of the malar eminences of the cranium, yellow-tinged conjunctivae, ulcers of the skin of the legs, an incorrectly healed fracture of the left leg, and massive splenomegaly. A peripheral smear reveals marked variation in the size and shape of the red blood cells, and nucleated red blood cells are present. Of the following, what is the most likely diagnosis?

A. Sickle cell anemia
B. β-thalassemia
C. Child abuse
D. Severe chronic malaria
E. Acute lymphoblastic leukemia
F. Acute and chronic cholecystitis

Answer for Question 149

Answer: B (β-thalassemia)

Explanation: In β-thalassemia major, the ineffective erythropoeisis leads to expansion of the marrow cavity, and hence the prominence of the malar eminences. Involvement of the long bones can predispose to fractures. The hemolysis associated with the ineffective erythropoeisis leads to an elevated concentrated of unconjugated bilirubin and can manifest as jaundice. And, while the unconjugated bilirubin can predispose to cholelithiasis, acute and chronic cholecystitis is not the sole cause of this child’s condition. On blood smear, β-thalassemia major has poikilocytosis (variation in cell shape) and anisocytosis (variation in cell size).