HETEROGENEITY OF GONADOBLASTOMA GERM-CELLS - SIMILARITIES WITH IMMATURE GERM-CELLS, SPERMATOGONIA AND TESTICULAR-CARCINOMA IN-SITU CELLS

Gonadoblastoma is defined as a neoplasm containing nests of germ cells and cells resembling Sertoli cells or granulosa cells, Gonadoblastoma s arise almost exclusively in dysgenetic gonads, They are associated w ith an increased risk of developing germ cell tumours, Testicular germ cell tumours in adults are preceded by carcinoma in situ cells, which are characterized by their morphology, by their immunohistochemical e xpression of placental-like alkaline phosphatase, the proto oncogene c -kit and/or epitopes for the monoclonal antibodies M2A, 43-9F and TRA- 1-60, and by their aneuploid DNA content. In order to elucidate if gon adoblastomas are ii? situ neoplasms from the beginning, showing simila rities with carcinoma in situ cells in otherwise normal testes, we inv estigated the germ cells in gonadoblastomas for their expression of th e immunohistochemical markers of carcinoma in situ cells from six pati ents aged 81/2 months to 20 years and 4 months, In addition, the DNA c ontent of the germ cells from five of the six patients was also determ ined by densitometric measurement on Feulgen stained specimens, The ge rm cell populations were heterogeneous both within the same patient an d between the patients, Expression of the testicular carcinoma in situ markers was detected in specimens from all the patients and germ cell s with an aneuploid DNA distribution pattern in accordance with testic ular carcinoma in situ cells were detected, However, apparently normal immature germ cells were also present in four of the patients of whom two also had germ cells with a morphology similar to normal spermatog onia, Thus, gonadoblastoma is most likely an in situ germ cell neoplas ia from the beginning, It seems probable that the germ cell tumours as sociated with gonadoblastomas originate from the carcinoma in situ cel ls inside the gonadoblastoma. Our findings of carcinoma in situ cells in gonadoblastomas from children support the theory that the cells aro se prenatally.