Emphysema
Summary
Emphysema is a chronic obstructive lung disease characterized by permanent enlargement of airspaces distal to the terminal bronchiole with destruction of alveolar walls and loss of elastic recoil. Classic boards split: smoking → centriacinar (upper lobes); alpha-1 antitrypsin deficiency → panacinar (lower lobes).
Detail
Pathogenesis is an imbalance between proteases (neutrophil elastase, macrophage MMPs) and antiproteases (alpha-1 antitrypsin). Smoking recruits neutrophils and oxidizes A1AT, leading to centriacinar/centrilobular emphysema involving the respiratory bronchioles of the upper lobes. A1AT deficiency (PiZZ genotype, misfolded protein accumulates in hepatocytes causing PAS-positive, diastase-resistant globules and cirrhosis) causes panacinar emphysema predominating in the lower lobes. Clinical: 'pink puffer' — dyspnea, pursed-lip breathing, hyperinflation with flattened diaphragms and increased AP diameter, decreased breath sounds, decreased DLCO. PFTs show decreased FEV1/FVC, increased TLC and RV. Paraseptal emphysema in young thin males predisposes to spontaneous pneumothorax.
Sources
- First Aid for USMLE Step 1 2024
- Robbins Basic Pathology 10th ed
- Pathoma
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