Testicular Dysgenesis and Mixed Gonadal Dysgenesis: Biochemical Characterization and Management of a Typical Case

Failure of fetal testis to differentiate and function during critical time periods can lead to varying degrees of undermasculinized genitalia, persistence of Mullerian structures, and underdifferentiation of Wolffian elements. Testicular dysgenesis associated with asymmetry of the genital system has been traditionally called “mixed gonadal dysgenesis”. A nine-month old child with a 46, XY non-mosaic peripheral and gonadal karyotype presented with ambiguous genitalia, had a normal vagina, uterus, and fallopian tubes, and intraabdominal gonads (a dysgenetic testis and a streak gonad containing changes consistent with gonadoblastoma). We report results of hCG and ACTH stimulation, radiologic studies, cytopathology and fibroblast culture for 5a-reductase activity and androgen receptor content. A bioassay for Mullerian inhibiting substance (MIS) failed to show presence of MIS in either gonad. Gonadectomy and reduction clitoroplasty were performed, and the feminine gender assignment was maintained. During gestation this patient had absolute deficiency of MIS function and partial deficiency of Leydig cell function. The presence of a gonadoblastoma by age 11 months underscores the need to remove these abnormal gonads early to prevent malignant degeneration.