A phenotypic male with true hermaphroditism and a 46,XX/46,XY/47,XXY karyotype.

A phenotypic boy presenting with gynaecomastia showed a mixed karyotype of 46,XX/46,XY/47,XXY. The left gonad was normally descended into the scrotum, but proved to be an ovary without any testicular structures. After left gonadectomy, plasma androgen and estrogen levels showed that the right gonad only contained testicular tissue. Seven patients with this form of triple mosaicism have been described but the clinical features are strikingly different among the described cases.