45,X mosaicism with Y chromosome presenting female phenotype

Prophylactic gonadectomy is recommended in patients with 45,X mosaicism with the Y chromosome and presenting a female phenotype because of the risk of gonadoblastoma development. The characteristics of this disorder remain unclear because of its low incidence. We report 4 patients with 45,X mosaicism with the Y chromosome and presenting complete female external genitalia. We analyzed the characteristics and the macroscopic and histopathological findings of their gonads and performed hormonal assays of the 4 patients. All 4 patients were referred to us with short stature as the chief complaint. Chromosomal studies revealed 45,X/47,XYY in 1, and the others had a 45,X/46,XY karyotype. Three patients (6 gonads) underwent laparoscopic bilateral gonadectomy. The macroscopic appearance of gonads of 1 patient was similar to an ovary, whereas gonads of the rest appeared as streak gonads. The histopathological findings revealed bilateral gonadoblastoma in 1 patient, although the macroscopic findings did not show tumor characteristics. It is impossible to distinguish the histopathological findings of gonads according to their macroscopic appearance among patients with 45,X mosaicism with the Y chromosome and presenting a female phenotype.