Prostatic tissue in a benign cystic teratoma of the ovary

A case of benign cystic teratoma of the ovary with two unusual features is reported. Besides the usual components of skin and its appendages, glia, cartilage, fat, smooth muscle and respiratory epithelium, the tumor contained prostatic tissue. Double Barr bodies were found in 15% of tumor cells. Since tissue differentiation in a teratoma is thought to follow similar rules to those of the fetus and since differentiation of prostate depends on testosterone, a source for this hormone had to be found. Several possibilities are discussed. The presence of double Barr bodies is consistent with parthenogenic origin of the teratoma before the first meiotic division or heteropyknosis of a solitary X chromosome in the tumor cells.