A fetal testis with intratubular germ cell neoplasia (ITGCN).

A fetal testis with abnormal germ cells similar to the cells of intratubular germ cell neoplasia (ITGCN) or so-called carcinoma in situ is presented. Elective abortion was performed in week 18 of the pregnancy of a 26-yr-old woman, because of 21 trisomy (Down's syndrome) at amniocentesis. At microscopical examination abnormal germ cells were found, similar to those occurring in the adult testis and with the same distribution as those described in ITGCN in children with dysgenetic gonads and with androgen insensitivity syndrome. PAS positivity and placental-like alkaline phosphatase (PLAP) was demonstrated in the abnormal germ cells. The finding indicates that the first event of germ cell tumor oncogenesis may take place before birth, in utero or even before. The occurrence of ITGCN in Down's syndrome has not been reported previously but is likely to occur, as there is evidence that these patients have increased risk of developing germ cell tumors.