[A case of occult testicular tumor].

A 43-year-old male presented with a left supraclavicular mass as well as an upper abdominal mass. Biopsy of the supraclavicular mass revealed seminoma with components of both embryonal carcinoma and choriocarcinoma. Right orchiectomy was performed because physical examination showed that the left testis was normal but the right testis was slightly atrophic. The primary tumor which was approximately 1 cm in diameter was found in the right testis and histological examination revealed seminoma. When germ cell tumor is found in a region other than the gonads, either primary extragonadal germ cell tumor or occult testicular tumor is considered. To differentiate between the two, it is imperative to make careful histological exploration of the testes.