[Pulmonary hemangiopericytoma preoperatively diagnosed as mediastinal tumor; report of a case].

An asymptomatic 67-year-old female was admitted because of an abnormal shadow on chest X-ray. Computed tomography (CT) revealed that a well-marginated round mass with low density, about 4 cm in diameter, was located in the right hilum. The border was enhanced at contrast material-enhanced CT. Magnetic resonance imaging (MRI) [T2-weighted] showed the lesion as a high intensity tumor. Because of the extra-pleural sign on CT and normal results of broncho-fiberscopic (BFS) examination, mediastinal tumor was suspected. We performed thoracoscopic surgery and revealed that the tumor was in lung, not in mediastinum. Biopsy of the easy-bleeding tumor was performed. The histopathological diagnosis was hemangiopericytoma. There was no remarkable change for 1 years. Hemangiopericytomas should be considered in the differential diagnosis of well-marginated masses. Thoracoscopic surgery is the useful methods to diagnose the hemangiopericytoma.