An up-date on newly discovered immunohistochemical biomarkers for the diagnosis of human testicular germ cell tumors.

Although testicular germ cell tumors (TGCTs) are relatively uncommon, they are particularly important, as they tend to affect children and young men, the most common tumor being in males aged from 20 to 40 years, and the incidence has been increasing in the last years. TGCTs comprise two major histologic groups: seminomas and non-seminomas germ cell tumors (NSGCTs). NSGCTs can be further divided into embryonal, carcinoma, Teratoma, yolk sac tumor, and choriocarcinoma. Seminomas and NSGCTs present significant differences in clinical features, therapy, and prognosis, and both show characteristics of the Primordial Germ Cells (PGCs). For proper diagnosis of the different histological subgroups, immunohistochemistry is required using different molecular markers, such as Aurora B, GPR30, Nek2, HMGA1, HMGA2, and others, and they could represent useful novel molecular targets for antineoplastic strategies. More insight into the pathogenesis of TGCTs is likely to contribute not only to better treatment of these tumors but also to a better understanding of stem cells and oncogenesis.