[Primary mediastinal seminoma--a case report].

Primary mediastinal seminoma is a rare germ cell tumor that is histologically identical to testicular seminoma. Fifty-one cases have been reported in the Japanese literature. This report concerns a new case of this tumor which showed high levels of a serum alkaline phosphatase (ALP) and a serum angiotensin converting enzyme (ACE). The patient is a 27 year old man whose father underwent an orchiectomy with postoperative radiation therapy for testicular tumor. After radiation and chemotherapy, the patient's chest X-ray showed complete regression of the mass, and his ALP and ACE decreased to normal levels.