45,X/46,XY ovotesticular disorder of sex development revisited: undifferentiated gonadal tissue may be mistaken as ovarian tissue.

Background: The 45,X/46,XY karyotype has been associated with mixed gonadal dysgenesis (MGD) and ovotesticular disorder of sex development (DSD). Our aim was to revise the diagnosis of ovotesticular DSD in two patients in the context of a retrospective study of 45,X/46,XY subjects with genital ambiguity.

Case Presentation: Patient 1 had a left streak gonad; the right one was considered an ovotestis. Patient 2 had a right testis; the left gonad was considered an ovary. Revision of the histological sections was performed. Both the "ovarian" part of the right gonad of patient 1 and the left "ovary" of patient 2 contained ovarian-type stroma with clusters of sex-cordlike structures and rare germ cells, compatible with undifferentiated gonadal tissue (UGT). Misdiagnosis of ovarian tissue in patients with 45,X/46,XY mosaicism or its variants could also be found in six published case reports.

Conclusions: A distinction between 45,X/46,XY ovotesticular DSD and MGD should be made on past and future cases keeping in mind that UGT may be mistaken as ovarian tissue.