Primary nonseminomatous germ cell tumor in the posterior mediastinum.

A 54-year-old man was admitted to our hospital for further examination following a chest radiographic screening test. He was asymptomatic but had an elevated serum concentration of alpha-fetoprotein. Chest computed tomography (CT) and magnetic resonance imaging showed a posterior mediastinal mass in the left thoracic paravertebral region. CT-guided percutaneous needle biopsy was performed, and the histological findings confirmed nonseminomatous germ cell tumor (NSGCT). Gonadal examination and F-18 fluorodeoxyglucose positron emission tomography findings indicated the posterior mediastinum as the origin of the disease. Reports of primary NSGCT in the posterior mediastinum are extremely rare.