Gonadotrophin-producing seminoma: a distinct category of germ cell neoplasm.

Gonadotrophin-producing seminomas can be identified in two ways: detection of human chorionic gonadotrophin (HCG) in the serum or urine, or histological identification of syncytiotrophoblastic giant cells, which can be shown to contain HCG by means of indirect immunoperoxidase techniques. A review of the histories of 14 patients with such tumours shows that they are associated with a worse prognosis than that of 'typical' seminomas, and tend to present with a more advanced stage of disease. These tumours are thus distinct, clinically and biologically, from typical seminomas, and their treatment needs to be planned accordingly.