Bullous emphysema

Emphysema is an enlargement of air spaces caused by destruction of alveolar walls. Air spaces greater than one cm are bullae. This photo shows apical bullous disease with relatively little involvement of the rest of the lung.

Centriacinar emphysema/distal acinar emphysema

This lung shows centriacinar emphysema with holes located around the terminal bronchioles and preservation of more distal air spaces. The parenchyma along the major fissure shows some distal acinar emphysema. Panacinar emphysema involves the entire acinus.

Centriacinar emphysema

This section of centriacinar emphysema shows the enlarged air spaces around a small airway. Respiratory epithelium remains at the arrow. The more peripheral alveoli are normal.

Pathogenesis of emphysema--proposed

This photo is taken from a patient with alpha-1-antitrypsin deficiency-related emphysema. It shows an increased number of PMNs in capillaries (arrows and many more) and some alveolar and interstitial blood. These PMNs, if activated, can potentially digest the collagen and elastin of the alveolar wall. Note the megakaryocyte in a capillary (arrowhead at top). Its function is not known, but any contribution of platelets would help to preserve the integrity of the capillary bed.