Hyperplasia of mesonephric remnant, epididymal type: A case report

Mesonephric rests or mesonephric remnants are vestiges of embryonic structures called mesonephric (wolffian) ducts. It usually can be seen in the lateral wall of the cervix uteri. In males, the mesonephric remnants are seen in epididymis and efferent ductules. Prostate is one of the rare locations, on which the mesonephric remnants can be found. Hyperplasia of mesonephric remnants of prostate is rare but important because sometimes it is difficult to differentiate from adenocarcinoma. The lesion is important in the differential diagnosis from the high grade prostatic intraepithelial neoplasia. Here, we report an additional case of mesonephric hyperplasia, epididymal type, in a 66-year-old man. Microscopically, it showed tubular structures lined by columnar cells with pseudostratified elongated hyperchromatic nuclei. The cells showed negative reaction on high molecular weight cytokeratin and prostate-specific antigen immunostain.