Leydig cell hypogenesis: a rare cause of male pseudohermaphroditism and a pathological model for the understanding of normal sexual differentiation.

We describe a patient who presented for treatment of primary amenorrhea and was found to have male pseudohermaphroditism due to Leydig cell hypogenesis. This rare disorder is characterized by ambiguous genitalia with a normal clitoris, labioscrotal folds, a urogenital sinus and inguinal or intra-abdominal testes microscopically devoid of mature Leydig cells. The diagnosis is made biochemically by the presence of low testosterone and estradiol values with elevated luteinizing hormone levels in the absence of other significant hormonal changes. The clinical and laboratory features of this disorder offer support for human developmental concepts derived from animal models.