Panacinar emphysema is classically associated with alpha-1 antitrypsin (AAT) deficiency and preferentially involves which zone of the lung?
- A Upper lobes predominantly, similar to centriacinar emphysema in smokers
- B Uniform distribution throughout but relatively more severe in lower lobes ✓
- C Lower lobes predominantly, as AAT concentrates in lower zones
- D Perihilar regions adjacent to major bronchi
Correct answer: B. Uniform distribution throughout but relatively more severe in lower lobes
Explanation
Panacinar (panlobular) emphysema in AAT deficiency involves the entire acinus uniformly, with relatively greater severity in the lower lobes (where blood flow and AAT deficiency effects are most pronounced). This contrasts with centriacinar emphysema (most common, associated with smoking), which predominantly affects the upper lobes. The uniform involvement of all parts of the acinus distinguishes panacinar from centriacinar disease.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
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