Prostatic remnants in mature cystic teratoma of the ovary.

Mature cystic teratomas of the ovary containing prostatic remnants are reported in 2 women aged 31 and 20 years. Both cases showed the expected histology of mature teratomas with a mixture of ecto- and endodermal structures lying in a fibrous stroma. In both cases, the foci of prostate tissue were composed of typical prostatic glands arranged in acinar structures. One case displayed a transitional cell-lined duct resembling the urethra. Prostate glands showed intense positive immunostaining with prostatic specific antigen and prostatic acidic phosphatase. Focal images suggesting high-grade prostatic intraepithelial neoplasia were detected in 1 case. The literature on this unusual finding in these common tumors is reviewed and commented on.