Testicular XO/XY Mosaicism in a Phenotypic Female with XY Sex Chromosomes in Other Tissues

A young woman with normal female external genitalia is described, who failed to develop breasts, menses and sexual hair, and was found to have intra-abdominal testes with XO/XY mosaicism. There was a rudimentary uterus with tubes. Leukocytes and skin cells showed an XY chromosome constitution. She did not resemble patients having the usual form of XO/XY mosaicism; on the other hand, she differed from the testicular feminization syndrome in that she did not feminize, and her testes were fibrotic and about half the size of those seen in the testicular feminization syndrome. The question is raised whether the failure to feminize may be causally related to the XO cell line in the testes.