Morphology and immunophenotyping of a monolateral ovotestis in a 46,XderY/45,X mosaic individual with ambiguous genitalia.

Disorders of sexual development represent a pathologic and clinical challenge. Many different clinical syndromes exist, and several classifications have been proposed in relation to different risks for malignant degeneration. The morphology, cytogenetics, and immunophenotype of a monolateral ovotestis in a 3-month-old individual with ambiguous genitalia and right inguinal mass are reported. The inguinal mass consisted of a tiny female genital tract with a hermaphroditic gonad with focal placental-like alkaline phosphatase-stained gonocytes; chromosome analysis disclosed a mosaic constitution: 46,XderY/45,X with a rearranged Y chromosome. A sharp morphologic distinction between true hermaphroditism and mixed gonadal dysgenesis probably does not exist, and cytogenetic characterization is mandatory. The presence of placental-like alkaline phosphatase-stained gonocytes indicates a high risk of malignant transformation, and justifies the surgical removal of the dysgenetic gonad. Fertility is unlikely.