[Gonadoblastoma and overgrowing dysgerminoma in Turner mosaicism [45, XO/46, Xi (Xq)] (author's transl)].

It is well established that the Y-chromosome is associated with germ cell tumor development. There is a considerable tumour risk in XY- and XY/XO-gonadal dysgenesis. In the absence of Y-chromosome germ cell tumours are extremely rare. The history of a patient with 45 XO/46 Xi (Xq)-karyotype is presented, who had a gonadoblastoma with overgrowing dysgerminoma. According to basal body temperature recordings, this patient ovulated up to the age of 22 years. After this cyclical ovarian function was exhausted; histologically no primordial follicles could be detected. Gonadotropin as well as prolactin binding sites in the tumours could not be demonstrated, suggesting hormone independency and complete malignant transformation of the tumor. In general the clinician should be aware of a possible germ cell tumour development in the absence of a Y-chromosome. However as far as the clinical management of patients with dysgenetic gonads is concerned, prophylactic gonadectomy is only indicated in the presence of a Y-chromosome.