Granulomatous pneumocystosis presenting as a solitary pulmonary nodule.

A case of pneumocytosis presented radiologically as a solitary pulmonary nodule. Of cases presenting in this unusual fashion, this may be the first in which the histology was that of a fibrous and granulomatous nodule. The only pathogen identified was Pneumocystis carinii. The expected histologic pattern in pneumocystosis (interstitial pneumonitis with foamy alveolar exudate) was completely absent. Outside the major pulmonary nodule, scattered microscopic noncaseating granulomas of sarcoid type were observed. Treatment in this case consisted only of segmental pulmonary resection, but no recurrence of pneumocytosis was observed.