Section: USMLE

60) A 45-year-old man with cirrhosis due to alpha1-antitrypsin deficiency receives a liver transplant. Although currently in good health, he is at increased risk of developing which of the following types of emphysema?

1. Centriacinar
2. Compensatory
3. Interstitial
4. Panacinar
5. Paraseptal

There are two main morphologic forms of emphysema, centriacinar and panacinar. The panacinar variant is related to alpha1-antitrypsin deficiency; the entire acinus is enlarged, from the respiratory bronchiole to the distal alveoli.

Centriacinar emphysema is characterized by enlargement of the central portions of the acinus, i.e., the respiratory bronchiole, and its pathogenesis is related to exposure to tobacco products and coal dust.

Interstitial emphysema is not a true form of emphysema. It results from penetration of air into the pulmonary interstitium. This may occur when alveolar tears develop because of a combination of coughing and airway obstruction (e.g., children with whooping cough) or a chest wound that injures the underlying lung parenchyma (e.g., a fractured rib).

Compensatory emphysema and paraseptal emphysema are associated with scarring. Both are frequent but usually clinically silent. Paraseptal emphysema, however, may lead to spontaneous pneumothorax in young patients. In fact, this form is more severe in areas adjacent to the pleura, where large, cyst-like structures may develop and rupture into the pleural cavity.