Mixed gonadal dysgenesis: histological and ultrastructural findings in two cases.

Mixed gonadal dysgenesis (MGD) is an intersex genetic abnormality characterized by a streak gonad and a contralateral testis (that is typically cryptorchid) or bilateral streak testes. A uterus and one or both fallopian tubes also may be present. The external genitalia are frequently ambiguous. We studied two phenotypic "females" with MGD. One had a mosaic 45X (40%) and 46XYq (60%) karyotype, a left streak gonad, and a small testis in a right inguinal hernia, whereas the other had a 46XY karyotype, a left streak gonad, and, on the right, a testis with gonadoblastoma. On histological and ultrastructural examination the testis in the first case showed prepubertal tubules lined by a few spermatogonia and immature Sertoli cells with asynchronism in nuclear-cytoplasmic maturation. Ultrastructural examination of the gonadoblastoma in the second case showed neoplastic Sertoli cells. Irregular maturation of Sertoli cells appears to be a feature of MGD. Gonadal extirpation and pathological examination in these cases are important in order to make the correct diagnosis and prevent neoplastic changes.