Diagnosis: Spermatocytic seminoma
• Spermatocytic seminoma is an uncommon germ cell tumor, distinct from classic seminoma histologically and therapeutically. Grossly it is a multinodular mass, grey-white in appearance. The histology is distinctive, featuring three cell types. The majority of the cells are intermediate cells, resembling the cells of classic seminoma. The more prominent cells are the large cells characterized by spireme type chromatin. Spireme type chromatin can be seen in both the intermediate and large cell types. The third and last population of cells is composed of small cells with dark, smudged pyknotic nuclei, the “lymphocytelike” cells. Mitotic figures are usually present.
• They are not usually associated with other germ cell tumors, in contrast to the other types of germ cell tumors, there is no known association with cryptorchidism, and the adjacent testis does not show intratubular germ cell neoplasia.
• Distinguishing spermatocytic seminoma from classic seminoma is sometimes tricky, and it is useful to know that similar to classic seminoma, spermatocytic seminoma usually does not express cytokeratin (CK), and can express PLAP and C-Kit (reported in rare cases). Perhaps the most useful marker so far has been OCT3/4, which should be positive in classic seminoma.
• Spermatocytic seminomas usually behave in a benign fashion and treatment consists of orchiectomy alone. When they undergo sarcomatous differentiation, however, they tend to behave more aggressively and have a high rate of metastases.
