[A case of sarcoidosis discovered by onset of pneumothorax].

A 24-year-old man was admitted to our hospital with left back and chest pain. A chest X-ray film showed left pneumothorax, bilateral hilar lymphadenopathy, mediastinal widening, and multiple nodular shadows in both lung fields. Chest CT showed a large nodule just under the pleura. High serum ACE and lyzozyme levels, and a noncaseating epithelioid granuloma (revealed by TBLB) led to the diagnosis of sarcoidosis. Steroid therapy was started to prevent a cardiac lesion. Pneumothorax secondary to sarcoidosis in its early stage is rare, and in this case the pneumothorax may have been caused by rupture into pleural space of the largest nodule in the left S9, as a result of necrosis.