Endometrial carcinoma in a patient having 45,X Turner syndrome with gonadal mosaicism

Only three cases of endometrial carcinoma in women with possibly pure 45,X Turner syndrome without previous unopposed estrogen therapy have been reported. A 46‐year‐old single nulligravid woman with Turner syndrome phenotype, spontaneous menstruation, and well‐differentiated adenocarcinoma of the endometrium was diagnosed as having the 45,X karyotype from peripheral blood, skin, buccal cells, and endometrium, which was confirmed using fluorescence in situ hybridization (FISH). Analysis of the ovarian tissue using FISH confirmed 45,X/46,XX mosaicism. Gonadal mosaicism may help to interpret spontaneous menstruation and endometrial carcinoma in possibly pure 45,X Turner syndrome. We conclude that a molecular analysis of lymphocytes and various tissues is necessary for detecting low‐level mosaicism in apparently homogeneous 45,X women.