Emphysema is defined as a destruction of alveolar walls and consequent enlargement of air spaces. The main known cause is cigarette smoke, but a few cases are caused by an inherited lack of the enzyme alpha-1-antitrypsin. Emphysema may involve different parts of the lung for reasons that are not clear. In the severe forms, all are associated with difficulty breathing (shortness of breath). The expiratory phase of breathing is prolonged and may be accompanied by audible wheeze.


This lung was dried and sliced. It shows marked emphysema, more severe at the top. Much tissue has been destroyed and the lung is larger than normal.

Closs-up of Emphysema

A close-up of the mid lung shows that some emphysematous holes are still surrounded by normal lung. The destroyed portion is around the small airways in this case.

Find 3 emphysematous holes. Remember to click on them to see if you are right.

Emphysematous change can be likened to Swiss cheese. The normal lung has a uniform cheddar cheese appearance. The Swiss cheese change comes about from enzymes that are activated by cigarette smoke. These enzymes eat away at the alveolar walls and cause holes.


Bullous Emphysema

This lung shows an example of localized, bullous emphysema (bulla = enlarged air space >1 cm in diameter). The emphysema is located at the top of the lung. Note that the tissue not involved in the emphysema appears almost normal in this case.

Find and outline the bulla.


Giant bullous emphysema: Giant bullae consume more than 1/3 of a lung radiographically. The remainder of the lung may be normal, as shown here. Isolated bullae with normal lung may be associated with few symptoms until bullae enlarge sufficiently to compress normal lung and interfere with function. Just as in diffuse emphysema, the localized cysts do not empty well on expiration. Most are caused by cigarette smoking. Radiographic studies can distinguish bullae with normal lung from bullae with diffuse emphysema. Patients with bullae in otherwise normal lung are a subset of patients who may benefit from excision of the bullae. 


























Bulla at the top of the lung































Emphysematous hole in lung