Pulmonary Pathology, Pathology, USMLE Step 1 - Full Vignette with Extended Explanations

Описание: A 40-year-old man experiences increasing exertional shortness of breath, dry cough for 18 months, and episodes of near-syncope with exercise. Physical exam reveals digital clubbing, inspiratory crackles, and an accentuated P2. Imaging and pulmonary function tests demonstrate restrictive changes and decreased diffusion capacity. Echocardiography suggests elevated right-sided pressures. What is the most critical complication explaining his worsening symptoms, and what clinical clues should heighten your concern for this development?

VIDEO INFO
Category: Pulmonary Pathology, Pathology, USMLE Step 1
Difficulty: Hard - Advanced level - Challenges experienced practitioners
Question Type: Complications
Case Type: Typical Presentation

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QUESTION
A 40-year-old man with progressive exertional dyspnea is evaluated after referral from a community clinic. He quit smoking 10 years ago after a 30-pack-year exposure. He works as a delivery driver and lives with his family. He reports 18 months of dry cough, reduced exercise tolerance, and three episodes of near-syncope on climbing stairs. He denies fever, chest pain, orthopnea, or leg swelling....

OPTIONS
A. Development of pre-capillary pulmonary hypertension with rising pulmonary vascular resistance leading to progressive right-sided heart failure
B. Transformation to small cell lung carcinoma arising from fibrotic lower-lobe reticulations within two years despite smoking cessation
C. Massive hemoptysis from acute bronchiectasis without airway infection, mycetoma, or anticoagulant exposure
D. Fulminant bacterial pneumonia in a vaccinated, immunocompetent adult with stable spirometry and no corticosteroid therapy

CORRECT ANSWER
A. Development of pre-capillary pulmonary hypertension with rising pulmonary vascular resistance leading to progressive right-sided heart failure

EXPLANATION
This patient with fibrotic interstitial lung disease (restrictive spirometry, reduced TLC, severely reduced DLCO, basal-predominant reticulation/traction bronchiectasis) has developed pre-capillary pulmonary hypertension (RHC: mPAP 34 mm Hg, PAWP 10 mm Hg, PVR 6.2 WU). In ILD, progression of pulmonary hypertension drives exertional intolerance and portends worse near-term mortality due to escalating right ventricular afterload and eventual right-sided heart failure. Recognition enables targeted therapy, oxygen optimization, and transplant referral where appropriate.

Alternatives do not explain his current trajectory or risk profile. Rapid transformation to small cell lung carcinoma from basal reticulation over two years is implausible and inconsistent with imaging. Massive hemoptysis without infection, mycetoma, or anticoagulation is not expected....


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