[Spermatocytic seminoma. A tumor with many faces].

Spermatocytic seminomas affect 0.3-0.8 per one million men. This tumor is not, as the name might suggest, a variant of classical seminoma but a distinct nosological entity, which differs markedly from all other germ cell tumors in its epidemiology, peculiar morphology, oncogenesis and clinical outcome. There are no racial differences in the incidence and risk factors are completely unknown. Patients are significantly older than is the case for other germ cell tumors with an average of 53.5 years; nevertheless, more than 25 % are younger than 40 years. Spermatocytic seminoma arises from differentiated spermatogonia, not from intratubular germ cell neoplasms. The tumor-specific gain of chromosome 9 seems to be the most important event in the oncogenesis. Conventional spermatocytic seminoma consists of three different cell types which give the tumor a highly aggressive appearance, although in actual fact, the tumor has a very favorable outcome, with few reported cases of general metastatic spread. Anaplastic spermatocytic seminoma, a recently described variant, also takes mostly a benign course; however, spermatocytic seminomas combined with sarcomas are extremely malignant.