Respiratory Pathology MCQS

Question 1

An 8-year-old boy had meconium ileus at birth, elevated sweat chloride, and recurrent Pseudomonas pneumonias. He is at greatest risk for which pulmonary abnormality?

Accepted Answer

Bronchiectasis — CF causes chronic airway inflammation and obstruction leading to bronchiectasis. Progressive loss of pulmonary vasculature leads to pulmonary hypertension and cor pulmonale.

Question 2

A 70-year-old nursing home woman with Alzheimer's develops fever and coughs up yellowish sputum. CXR shows left lower lobe infiltrate. Sputum shows neutrophils and gram-positive diplococci. Most likely organism?

Accepted Answer

Streptococcus pneumoniae — Gram-positive diplococci + lobar pneumonia in a community/nursing home setting = Streptococcus pneumoniae, the most common cause of community-acquired pneumonia.

Question 3

An 11-year-old girl has 2 weeks of dyspnea. CXR shows hilar lymphadenopathy and a 1 cm peripheral right middle lobe nodule. No infiltrates. Sputum shows normal flora. Most likely condition?

Accepted Answer

Mycobacterium tuberculosis infection — Peripheral nodule + hilar lymphadenopathy in a child = Ghon complex of primary TB. Enlarged nodes may compress airways causing dyspnea. Most primary infections are asymptomatic.

Question 4

On postoperative day 11 after a radical prostatectomy, a 70-year-old man suddenly becomes extremely dyspneic, diaphoretic with chest pain after walking to the bathroom. Most likely pulmonary complication?

Accepted Answer

Thromboembolus — Prolonged immobilization after surgery → DVT → pulmonary thromboembolism upon ambulation. Classic sudden-onset presentation.

Question 5

A 50-year-old Swedish non-smoking seamstress has dyspnea, fever, hilar lymphadenopathy, reticulonodular infiltrates, anergy on skin testing, and non-caseating interstitial granulomas on biopsy. Most likely diagnosis?

Accepted Answer

Sarcoidosis — Non-caseating granulomas + hilar lymphadenopathy + anergy = sarcoidosis. Corticosteroids are the treatment but infection must be excluded first.

Question 6

A 43-year-old woman has 8 years of worsening dyspnea, hyperresonance on percussion, increased lung volumes on CXR, and decreased attenuation in lower lobes on CT. Most likely lab finding?

Accepted Answer

Decreased serum alpha-1-antitrypsin — Emphysema in a non-smoker affecting lower lobes = alpha-1-antitrypsin deficiency. Loss of anti-protease activity leads to panlobular emphysema by the 5th decade.

Question 7

A 55-year-old 50-pack-year smoker has hemoptysis. Sputum cytology shows atypical cells with hyperchromatic nuclei and orange-pink cytoplasm. Serum calcium is 11.3 mg/dL. Most likely CXR finding?

Accepted Answer

Large hilar mass — Squamous cell carcinoma is central in location, arising in large bronchi, causing a hilar mass. Hypercalcemia is a paraneoplastic feature of squamous cell carcinoma.

Question 8

A 58-year-old non-smoker aspirates gastric contents during intubation. Over 10 days he develops a cough, fever, and a 4 cm right lung mass with an air-fluid level. Sputum shows mixed flora. Most likely condition?

Accepted Answer

Lung abscess — Aspiration + air-fluid level in the right lung = lung abscess. The right mainstem bronchus is straighter, conducting aspirated material more readily. Mixed flora is typical.

Question 9

A 66-year-old woman has a week of non-productive cough, mild fever, and bilateral interstitial infiltrates on CXR. Sputum shows normal flora and few neutrophils. She recovers fully in 2 weeks. Most likely organism?

Accepted Answer

Influenza A virus — Bilateral interstitial infiltrates + non-productive cough + few neutrophils + full recovery = viral pneumonia. Influenza A is the most common cause. T lymphocytes dominate the interstitial inflammation.

Question 10

A 58-year-old smoker has 2 months of non-productive cough and blood-streaked sputum. CXR shows a 5 cm left hilar mass. Sputum cytology shows small hyperchromatic cells with scant cytoplasm. Most likely predisposing factor?

Accepted Answer

Smoking — Small cell anaplastic carcinoma is virtually always seen in smokers. It arises centrally and spreads aggressively. Smoking remains the most frequent cause of lung cancer overall.

Question 11

A 41-year-old man with weight loss, low CD4 count of 79, and Cryptosporidium in stool has bilateral patchy infiltrates. BAL yields pink foamy exudate with little inflammation. Most likely additional finding on GMS stain?

Accepted Answer

Multiple cysts with GMS stain — Pink foamy exudate + severely low CD4 = Pneumocystis jiroveci pneumonia. GMS stain reveals the characteristic cysts. PCP is the most common AIDS-defining opportunistic lung infection.

Question 12

A 64-year-old 90-pack-year smoker has had productive cough with copious mucoid sputum for more than 3 months per year for 5 years. He dies of septicemia and brain abscess. Autopsy shows mucus gland hypertrophy. Most likely diagnosis?

Accepted Answer

Chronic bronchitis — Chronic bronchitis is defined as productive cough for at least 3 months in at least 2 consecutive years. Mucus gland hypertrophy is the pathologic hallmark. Smoking and air pollution are the key causes.

Question 13

A 66-year-old retired construction worker has dyspnea, bilateral diaphragmatic pleural plaques with calcification on CXR, diffuse interstitial disease, and ferruginous bodies on sputum cytology. Low FVC with normal FEV1/FVC. Most likely exposure?

Accepted Answer

Asbestos crystals — Pleural plaques with calcification + ferruginous bodies (iron-encrusted asbestos fibers) + restrictive pattern = asbestosis. Building construction is a classic occupational exposure.

Question 14

A 58-year-old smoker with obesity, BP 165/110, HgbA1C of 10%, and worsening orthopnea has bilateral lower lobe rales and infiltrates on CXR with a prominent left heart border. Most likely pulmonary problem?

Accepted Answer

Pulmonary edema — Hypertension + diabetes + obesity + smoking = multiple risk factors for left heart failure. Pulmonary edema results from elevated left-sided filling pressures causing fluid in the alveoli.

Question 15

A 47-year-old man has lost 6 kg, has hemoptysis, pleuritic chest pain, and bilateral upper lobe infiltrates with cavitation. Sputum shows epithelioid cells with necrotic debris. Most likely additional histologic finding?

Accepted Answer

Acid fast bacilli — Cavitating upper lobe infiltrates + epithelioid granulomas with caseous necrosis + constitutional symptoms = tuberculosis. Acid fast bacilli (Mycobacterium tuberculosis) are the expected finding.

Question 16

A 20-year-old man collapses while jogging with a minor hand abrasion. He rapidly develops dyspnea, absent right breath sounds, and mediastinal shift to the left. Thoracentesis yields a rush of air. Most likely condition?

Accepted Answer

Distal acinar emphysema — Spontaneous pneumothorax in a young man with no trauma = distal acinar (paraseptal) emphysema with subpleural bullae. Pulmonary function tests are normal between episodes.

Question 17

A 30-year-old man is intubated after severe hypotension from a vehicular accident. Despite increasing PEEP and 100% FiO2, saturations worsen. He dies. Autopsy shows hyaline membranes, thickened interstitium, and macrophages. Most likely pulmonary complication?

Accepted Answer

Diffuse alveolar damage — Hyaline membranes + thickened interstitium after severe hypotension = diffuse alveolar damage (ARDS). It is the final common pathway following severe lung injury from shock, sepsis, or oxygen toxicity.

Question 18

A 51-year-old non-smoker has a slight cough for a week. Lung fields are clear. CXR shows a subpleural 2 cm coin lesion in the right upper lobe. Most likely diagnosis?

Accepted Answer

Granuloma — Solitary peripheral coin lesion in a non-smoker = most likely a granuloma from prior subclinical TB or fungal infection. Differential also includes adenocarcinoma and hamartoma.

Question 19

A 61-year-old man has a cough and right lower lobe consolidation. Antibiotic therapy over a month fails to resolve it. BAL yields atypical cells and alveolar macrophages. Most likely diagnosis?

Accepted Answer

Adenocarcinoma-in-situ — Consolidation that does not respond to antibiotics + atypical cells on BAL = adenocarcinoma-in-situ (formerly bronchioloalveolar carcinoma). It can spread in a pneumonia-like pattern and occurs in non-smokers.

Question 20

A 25-year-old man receives a stem cell transplant for AML. Three weeks later he develops dyspnea, fever, and interstitial infiltrates. BAL cytology shows enlarged cells with prominent intranuclear inclusions. Most likely organism?

Accepted Answer

Cytomegalovirus — Enlarged cells with prominent intranuclear inclusions = CMV cytopathic effect. CMV pneumonitis is a classic complication in immunocompromised transplant patients before engraftment.

Question 21

A 54-year-old woman has a month of fever, dyspnea, and weight loss. CXR shows reticulonodular pattern and hilar lymphadenopathy. Transbronchial biopsy shows no organisms, no viral inclusions, no atypical cells. Most likely disease?

Accepted Answer

Sarcoidosis — Non-caseating granulomas with no identifiable organism + hilar lymphadenopathy = sarcoidosis. The absence of organisms on thorough workup is key before starting corticosteroids.

Question 22

A 59-year-old 42-year smoker has blood-streaked sputum, back pain, a right hilar mass, peripheral lung nodules, and vertebral bone scan uptake. Sputum shows small hyperchromatic cells with scant cytoplasm. Most likely lab finding?

Accepted Answer

Serum sodium of 113 mmol/L — Small cell carcinoma produces ADH (SIADH), causing severe hyponatremia. Small cell is the lung cancer most associated with paraneoplastic syndromes due to its neuroendocrine origin.

Question 23

A 40-year-old woman has a week of high fever, productive yellowish cough, diffuse rales, patchy infiltrates in all lung fields, and a 4 cm rounded consolidation with an air-fluid level in the left upper lobe. Most likely organism?

Accepted Answer

Staphylococcus aureus — Bronchopneumonia complicated by an abscess with air-fluid level = Staphylococcus aureus. More virulent bacteria cause liquefactive necrosis resulting in abscess formation.

Question 24

At autopsy, a 60-year-old man has a peripheral 7 cm golden-yellow consolidated area distal to a 3 cm hilar mass. Microscopically, alveoli are filled with foamy macrophages. Most likely underlying condition?

Accepted Answer

Squamous cell carcinoma — Central hilar mass obstructing a large bronchus → distal lipid (endogenous) pneumonia with foamy macrophages = squamous cell carcinoma. Most squamous cell carcinomas are centrally located.

Question 25

A 12-year-old girl has acute dyspnea and wheezing, coughs up a thick mucus plug, and has 11% eosinophils on CBC and eosinophils in sputum. Similar episodes have occurred for 4 years. Most likely diagnosis?

Accepted Answer

Bronchial asthma — Recurrent episodic wheezing + mucus plugs + peripheral and sputum eosinophilia in a child = bronchial asthma. Atopic asthma is initiated by type I hypersensitivity to allergens.

Question 26

A 41-year-old non-smoking woman has recurrent fever, non-productive cough, and dyspnea that resolved on vacation but returned when she came home to care for her canaries. Fine nodular infiltrates on CXR. Most likely inflammatory mechanism?

Accepted Answer

Antigen-antibody complex formation — Bird feather dust inhalation → extrinsic allergic alveolitis (hypersensitivity pneumonitis) via type III (immune complex) hypersensitivity. Can progress to type IV if chronic.

Question 27

A 63-year-old woman has 5 years of worsening dyspnea, hyperresonance, expiratory wheezes, increased lung volumes, and FEV1/FVC less than 70%. Which inhaled substance increases neutrophil elastase and most likely caused her disease?

Accepted Answer

Nicotine — Nicotine is chemotactic for neutrophils and activates the alternative complement pathway. Cumulative neutrophil elastase activity over years destroys lung parenchyma, causing smoking-related emphysema.

Question 28

A 29-year-old woman develops fever, dyspnea, non-productive cough, loss of smell, and ground-glass opacities on CXR. A single-stranded RNA virus is recovered. Three months later she still has myalgias, dyspnea, fatigue, and memory loss. Most likely virus?

Accepted Answer

Coronavirus — Loss of smell + ground-glass opacities + single-stranded RNA virus + persistent symptoms beyond 3 months = COVID-19 (SARS-CoV-2). "Long COVID" affects at least a third of infected persons.

Question 29

A 44-year-old non-smoking woman has fever and cough. CXR shows a 6 cm right upper lobe infiltrate. Antibiotics fail to clear it; one month later a 3 cm peripheral mass is seen. Most likely neoplasm?

Accepted Answer

Adenocarcinoma — Peripheral lung mass in a non-smoker that presented as a persistent "pneumonia" = adenocarcinoma. Peripheral lung cancers (adenocarcinoma, large cell) are less strongly associated with smoking than central ones.

Question 30

A 70-year-old bedridden woman (post-CVA, 5 weeks) has sudden dyspnea then 2 days later develops left-sided pleuritic chest pain. Imaging shows a wedge-shaped hemorrhagic area at the left lower lobe pleura. Most likely finding in her pulmonary arteries?

Accepted Answer

Thromboembolism — Immobility → DVT → pulmonary thromboembolism → wedge-shaped hemorrhagic infarct at the pleural base. Pleuritic chest pain indicates pleural involvement by the infarct.

Question 31

A 38-year-old woman has a non-productive cough for 4 days, low-grade fever, patchy interstitial infiltrates, mixed flora on gram stain, and an elevated cold agglutinin titer. She responds to erythromycin. Most likely organism?

Accepted Answer

Mycoplasma pneumoniae — Elevated cold agglutinin titer + interstitial infiltrates + response to erythromycin = Mycoplasma pneumoniae (primary atypical pneumonia). Not cultured by routine bacterial methods.

Question 32

A 23-year-old primigravida with elevated HgbA1C delivers at 33 weeks. The infant is in severe respiratory distress requiring intubation within an hour. What pharmacologic therapy given to the mother could have helped prevent this?

Accepted Answer

Hydrocortisone — Maternal diabetes impedes fetal lung maturation and surfactant production. Antenatal corticosteroids (hydrocortisone/betamethasone) accelerate type II pneumocyte maturation and surfactant production in the fetus.

Question 33

A 51-year-old woman has 5 months of progressive lower leg swelling. CXR shows bilateral pleural effusions and prominent right heart border. AST, ALT, and LDH are elevated; CK is normal. Most likely underlying disease?

Accepted Answer

Recurrent thromboembolism — Recurrent pulmonary emboli → pulmonary hypertension → right heart failure → hepatic passive congestion → elevated transaminases and LDH but normal CK (no myocardial ischemia).

Question 34

A cardiac transplant patient one month post-op develops fever, cough, and left lower lobe abscess on CT. Sputum shows normal flora. He fails antibiotics for 6 months and develops multiple brain abscesses. Most likely organism?

Accepted Answer

Nocardia braziliensis — Pulmonary abscess + brain dissemination in an immunocompromised patient not responding to standard antibiotics = Nocardia braziliensis. Brain involvement is a characteristic feature of disseminated nocardiosis.

Question 35

A previously healthy 5-year-old girl has fever, expiratory wheezes, and suddenly worsening dyspnea. WBC is 14,480. Emergency bronchoscopy reveals bronchi plugged by exudates. Most likely organism?

Accepted Answer

Haemophilus influenzae — High WBC + bronchi plugged by fibrin-rich neutrophilic exudates in a child after descending laryngotracheobronchitis = Haemophilus influenzae. Can cause bronchopneumonia with airway obstruction.

Question 36

A study reviews adults with sudden severe dyspnea, absent breath sounds over an entire lung, and complete pulmonary atelectasis on CXR. They are afebrile. Most likely cause?

Accepted Answer

Penetrating chest trauma — Penetrating chest trauma → pneumothorax → complete lung collapse (atelectasis). Absent breath sounds over the entire lung with sudden onset in an afebrile patient points to pneumothorax from trauma.

Question 37

A newborn male at 36 weeks gestation develops severe respiratory distress within an hour, requiring mechanical ventilation. He dies within 2 days. Autopsy shows extensive pink hyaline membranes. Most likely maternal condition that increased this risk?

Accepted Answer

Gestational diabetes — Gestational diabetes → fetal hyperinsulinism → impaired type II pneumocyte development → insufficient surfactant → hyaline membrane disease. Diabetes impedes fetal lung maturation even at 36 weeks.

Question 38

A 10-year-old boy develops neck pain and halitosis 4 days after acute pharyngitis. CT shows a peritonsillar abscess growing anaerobic flora. Most likely aerobic organism also cultured?

Accepted Answer

Group A Streptococcus — Peritonsillar abscess is a classic complication of streptococcal (Group A Strep) pharyngitis in children. The abscess contains mixed flora including anaerobes and the original streptococcal pathogen.

Question 39

A 65-year-old non-smoker has an 8 kg weight loss, malaise, non-tender supraclavicular lymphadenopathy, and multiple solid nodules 1–3 cm throughout all lung fields on CXR. No fever or cough. Hgb 11.6. Most likely pathologic process?

Accepted Answer

Metastatic carcinoma — Multiple bilateral solid pulmonary nodules + weight loss + supraclavicular lymphadenopathy in a non-smoker = metastatic carcinoma. Multiple nodules favor metastases over a primary lung tumor.

Question 40

A 43-year-old non-smoking woman has 8 years of progressive dyspnea, hyperresonance, decreased breath sounds, and increased lucency on CXR. Serum alpha-1-antitrypsin is 18 mg/dL. Which portion of the lung is most likely affected?

Accepted Answer

Alveolar duct — AAT deficiency causes panacinar emphysema, destroying the distal acinus beyond the respiratory bronchiole, including the alveolar ducts and alveolar sacs. Lower lobes are more severely affected.

Question 41

A baby is delivered at 28 weeks after sudden placental abruption. The infant requires intubation and ventilation. CXR shows bilateral opacification the next day and the baby does not improve. Most likely histopathologic finding?

Accepted Answer

Minimal alveolar saccular development — Extreme prematurity (28 weeks) → lungs lack sufficient alveolar development and surfactant production → hyaline membrane disease. The primary finding is minimal alveolar saccular development.

Question 42

A 41-year-old woman has episodic dyspnea with expiratory wheezes, elevated serum IgE, peripheral eosinophilia, sputum eosinophils, perihilar bronchiectasis on CXR, and detectable serum galactomannan. Most likely pathologic finding in her bronchi?

Accepted Answer

Non-invasive aspergillosis — Elevated IgE + eosinophilia + galactomannan (Aspergillus cell wall component) + bronchiectasis + asthma exacerbations = allergic bronchopulmonary aspergillosis (ABPA). The fungus colonizes bronchi non-invasively.

Question 43

A male infant born at 30 weeks requires intubation immediately after birth. Two months later he is taken off the ventilator but still oxygenates poorly. Most likely disease developed?

Accepted Answer

Bronchopulmonary dysplasia — Prematurity + prolonged mechanical ventilation with high FiO2 → bronchopulmonary dysplasia (BPD). Positive pressure ventilation, oxygen toxicity, and prolonged intubation all contribute to this chronic lung injury.

Question 44

A 6-year-old has sudden dyspnea, absent right breath sounds, and is afebrile. ABG shows pO2 95, pCO2 25, pH 7.55. After 100% FiO2, the ABG is unchanged. Most likely diagnosis?

Accepted Answer

Foreign body aspiration — Complete bronchial obstruction from a foreign body → V/Q mismatch shunt defect → 100% oxygen does not improve pO2 because no ventilation reaches the perfused lung. Respiratory alkalosis from hyperventilation.

Question 45

A 60-year-old woman develops multi-organ failure after septic pneumonia. Cultures are now clear, but she requires increasing ventilatory pressures and her CXR shows progressive opacification of all lung fields. Most likely pathologic process?

Accepted Answer

Diffuse alveolar damage — Progressive respiratory failure despite cleared infection + increasing opacification = diffuse alveolar damage (ARDS). It is the final common pathway for severe lung injury from sepsis, producing hyaline membranes and restrictive physiology.

Respiratory Pathology MCQS

Questions, Answers & Explanations