[Asymptomatic Chronic Expanding Hematoma Following Previous Cardiac Surgery Diagnosed by Computed Tomography-guided Biopsy:Report of a Case].

A 48-year-old man was referred to our hospital with an intrapericardial mass, which was incidentally found by computed tomography( CT) in a health check-up. He had undergone surgical closure of atrial septal defect 23 years ago. Although echocardiography and CT revealed compression of the right ventricle by a mass, he had no symptoms and echocardiography revealed no significant right ventricular overload. Magnetic resonance imaging revealed a mosaic pattern of various signal intensities. We performed a CT-guided biopsy, and the histological result was a hematoma. This was the first reported case of chronic expanding hematoma following previous cardiac surgery diagnosed by CT-guided biopsy.