Chronic Pneumocystis carinii pneumonia in AIDS.

The clinical and radiologic presentation as well as the macroscopic and histologic characteristics of lung parenchyma in three HIV-infected patients with Pneumocystis carinii pneumonia (PCP) are detailed. The distinguishing clinical feature in these patients was a prolonged stable clinical course of the disease over at least 4 to approximately 24 months. Serial chest radiographs in two patients demonstrated persistent focal radiographic lesions. In one patient blebs in both upper lobes were not recognized until thoracoscopy/thoracotomy was performed. Biopsy specimens of affected areas revealed extensive interstitial fibrosis, occasional giant cell reactions, and honeycombing. In view of the combined clinical, radiologic, macroscopic, and histologic patterns, it is suggested that these patients had a chronic productive form of PCP rather than the well-known acute presentation of the disease. Data from the literature confirm the impression that atypical histologic lesions of PCP, either of a productive or destructive nature, are frequently related to a prolonged clinical course. It is unlikely that prophylactic pentamidine contributes to this entity. Coinfection with other pathogens may have a role. Given the recent evidence on augmented release of tumor necrosis factor a (TNFa) in HIV-associated pulmonary complications, it is speculated that TNFa may be of importance in producing focal fibrosis in Pneumocystis infection of the lung.