A 45-year-old man with a 20-pack-year smoking history has FEV1/FVC ratio of 0.60 and FEV1 42% of predicted. His lung biopsy shows panacinar emphysema predominantly in the lower lobes. This pattern is most characteristic of:
- A Usual smoker-related emphysema (centriacinar, upper lobe predominant)
- B Alpha-1 antitrypsin deficiency (panacinar, lower lobe predominant) ✓
- C Distal acinar (paraseptal) emphysema near pleura
- D Compensatory emphysema following lobectomy
Explanation
Panacinar (panlobular) emphysema with lower lobe predominance is the pathological signature of alpha-1 antitrypsin (AAT) deficiency, an autosomal recessive condition where insufficient AAT allows unopposed neutrophil elastase activity throughout the entire acinus. The lower lobe predominance reflects greater airflow and higher proteolytic burden in dependent lung zones. Centriacinar emphysema in upper lobes is characteristic of tobacco-related COPD. Distal acinar (paraseptal) emphysema occurs near pleura and septa, predisposing to spontaneous pneumothorax. AAT deficiency also causes liver disease (PiZZ phenotype, where misfolded Z-variant protein accumulates in hepatocytes).
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.