Testicular seminoma in a patient with ataxia-telangiectasia.

The case history of a 27-year-old man with ataxia-telangiectasia (AT) and testicular seminoma is reported. This is the first documented description of such a malignancy in AT, a syndrome associated with a markedly increased risk of malignant disease. Furthermore, alpha-foetoprotein levels have limitations as a tumour marker in this situation because serum levels may be elevated as a biochemical manifestation of AT.