Cystic Disease in Pneumocystis Carinii Pneumonia

In this slice of postmortem lung from an AIDS patient, who did not respond to anti-pneumocystis therapy, innumerable cavities, up to about 1 cm in diameter, were found. These cavities have thin walls and occur in the pale yellowish parenchyma that occupies most of the upper lobe. The pallor indicates ischemia.

Microscopically, organisms were easily found in alveolar septa around the cavities, and septal lysis may have occurred to produce the cavities. Inflammation was minimal, and there was no evidence of angiitis.

The subpleural cavities near the apex are the ones likely to rupture and cause pneumothorax. The red parenchyma of the lower lobe is also consolidated, and microscopically, alveoli were filled with foamy exudate, which did not invade alveolar walls or compromise the blood supply in this area.

In a review of 100 consecutive radiographs of AIDS patients, pneumatoceles, corresponding to the cavities shown above, were found in 10. The spaces were empty and thin-walled and had no predilection for any part of the lung. After treatment, most resolved within 7 months [1].

References:

1. Sandhu J, Goodman P. Pulmonary cysts associated with Pneumocystis carinii pneumonia in patients with AIDS. Radiology 1989; 173:33-35.

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