Hyperplasia and hypertrophy of Leydig cells associated with testicular germ cell tumours containing syncytiotrophoblastic giant cells.

In patients with seminomas and non-seminomatous germ cell tumours of the testis syncytiotrophoblastic giant cells (STGC) are largely responsible for elevated levels of chorionic gonadotropin. In searching for these cells, the question arises whether hyperplasia and/or hypertrophy of Leydig cells in the adjacent testicular tissue is a relevant finding. To elucidate this problem we analysed the tumour-free testicular tissue of 20 seminomas and 20 combined seminomatous and non-seminomatous germ cell tumours with or without immunohistochemically demonstrable STGC morphometrically. Extension of Leydig cell areas and the surface areas of Leydig cells per tubule are increased significantly in seminomas and combined tumours when STGC are present. There is also an apparent increase in the number of Leydig cells per tubule in seminomas and combined germ cell tumours with STGC. The difference, however, is not significant statistically in the group of seminomas. Hypertrophy and/or hyperplasia of Leydig cells must be considered as a relevant finding in germ cell tumours with STGC. It is most easily recorded by evaluating the surface area of Leydig cells per test area or per tubule.