Tubular seminoma of the testis

A case of tubular seminoma in a 33-year-old man is reported. The tumor occurred in his right testis, measuring 7 x 6 x 6 cm in size. Microscopically, most of the tumor cells were arranged in solid or hollow tubular patterns. The tumor cells had round nuclei with vesicular chromatin and clear or granular cytoplasm, characteristic features of seminoma cells. A classic seminoma component and intratubular atypical germ cells occupying approximately 5% of the tumor area were noted. Immunohistochemical staining revealed that the tumor cells were diffusely placental alkaline phosphatase and vimentin positive, and focally cytokeratin positive. These findings are consistent with a tubular seminoma. The differential diagnoses are discussed.