Testis: Germ cell tumors

Two main entities may be distinguished within testicular germ-cell tumours: seminomas and non seminomatous germ-cell tumours (NSGCT). Seminomas are composed of neoplastic germ cells. Non seminomatous germ-cell tumours present multiple histologic subtypes with neoplastic 1embryonic tissues (embryonal carcinoma, immature and mature teratoma), or 2extraembryonic tissus (yolk sac tumour and choriocarcimoma), which are usually associated and are therefore called mixed germ cell tumours (the most frequent being teratocarcinoma). There may been combined tumours of seminomatous and non seminomatous components. Intratubular germ cell neoplasia (ITGCN), also called carcinoma in-situ, appears as a precursor lesion of invasive tumours (common precursor for both seminomas and NSGCT), but it can also be observed in patients without development of a testicular germ-cell tumour (GCT). In adults, most testicular germ cell tumours are associated with ITGCN surrounding the invasive cancer.