[Primary pulmonary hemangiopericytoma detected on routine chest X-ray examination].

Hemangiopericytoma is a rare tumor originating from pericytes. In May 1988, a 33-year-old man was found to have a well-defined nodular shadow in the right upper lobe during a routine chest X-ray examination. Although the mass had been thought to be benign, in December 1992 it was found to have grown. In May 1993, the patient was referred to our hospital for further examination. A chest X-ray film and a high-resolution CT scan revealed a well-defined nodule in the right upper lung field without vascular gathering or pleural puckering. The tumor was slightly less dense than was soft tissues. There was no evidence suggesting another primary tumor or metastasis. In July 1993, because the mass was suspected to be a low-grade malignant tumor, a segementectomy (rt-S2) was done. On the basis of histologic, immunohistochemical and electronmicroscopic findings, pulmonary hemangiopericytoma was diagnosed. The postoperative course was uneventful. The patient has been well for 2 years and five months after the operation, with no sign of recurrence or metastasis.