Unique finding of prostatic tissue in a benign cystic ovarian teratoma

Benign cystic ovarian teratomas are neoplasms with a 46,XX karyotype originating from a single abnormal ovarian germ cell after the first meiotic division. Since these tumors lack the Y chromosome (required for production of the H-Y antigen that is presumably obligatory for embryonic male sexual differentiation), identifiable male sex organ structures should not be found in the tumor. We report a case in which prostatic tissue was identified in a benign cystic ovarian teratoma.