Gonadoblastoma: unusual presentation in a patient lacking persistent müllerian ducts

We report a patient with a disorder of sexual differentiation who presented with a 46,XY karyotype, absent internal Müllerian ducts, a vaginal pouch, hypospadias, and bilateral cryptorchidism with a gonadoblastoma in one testis. A human chorionic gonadotropin stimulation test and tissue 5-alpha-reductase and androgen receptor assays were normal. Except for the absence of internal Müllerian ducts, this patient most closely resembles the disorder of dysgenetic male pseudohermaphroditism (DMP). On this basis, we hypothesize that the internal Müllerian ducts in DMP may manifest anywhere along a spectrum that extends from normal to complete absence of structures depending on the degree of gonadal dysgenesis. This case also illustrates the importance of testicular biopsy in patients with dysgenetic testes because of the high likelihood of germ cell neoplasms in these gonads.