CT of primary germ-cell tumors of the mediastinum.

Primary mediastinal germ-cell tumors are rare neoplasms that usually occur in young men. Computed tomographic (CT) scans in four patients demonstrated large anterior mediastinal masses obliterating fat planes and extending inferiorly along the left mediastinal border. Nonseminomatous tumors contained areas of near-water density (cyst formation and/or necrosis) as well as soft-tissue density. Although CT features may suggest the diagnosis before histologic confirmation, the most important roles of CT are evaluation of extent of disease and monitoring response to therapy.