[Spontaneous pneumothorax disclosing isolated pleural involvement caused by Pneumocystis carinii in an AIDS patient].

We report a case of apparently isolated pleural Pneumocystis carinii infection in an AIDS patient under primary prophylaxis with pentamidine aerosols. Owing to the absence of the usual radiological signs and to negative broncho-alveolar lavages the diagnosis was difficult, and only pleural biopsy during thoracotomy made it possible. P. carinii cysts were demonstrated by Grocott's silver staining. Histological study of lung biopsy fragments only showed giant-cell granulomas of the foreign body type, with numerous calcifications. The occurrence of pneumothorax, ascribable in this patient to a minute and probably missed pulmonary focal lesion, was caused by the rupture of bullae remaining from an old tuberculosis.