[Germ cell and sex cord-stromal tumors of the testis : WHO classification 2016].

Earlier revisions of the WHO classification of testicular tumors, which was originally published in 1977, contained only minor additions. In the WHO 2016 classification, in contrast, germ cell tumors are split into two major groups based on their distinct pathohistogenesis, i. e., those which derive from an in situ forerunner lesion and those which do not. The latter category includes prepubertal yolk sac tumors and teratomas, as well as spermatocytic seminoma. The classification of yolk sac tumors and teratomas as arising before or after puberty is also of prognostic value. The group of trophoblastic tumors has also been divided into choriocarcinoma and "nonchoriocarcinomatous trophoblastic tumors," which are rare but may also be clinically significant. The changes in the classification of the sex cord-stromal tumors are not particularly important; rare variants without clinical importance of the single well-known tumors have been omitted. A new entity, a kind of "in situ" large cell Sertoli cell neoplasia, has been introduced.