Primary vaginal adenocarcinoma arising from the metanephric duct remnant

Primary vaginal adenocarcinoma unrelated to in utero exposure to diethylsti lbestrol (DES) is very uncommon. We report a case of 65-year-old Japanese w oman who presented with primary adenocarcinoma in the anterior wall of the vagina, where the left ureter-like metanephric duct remnant abnormally term inated. Histological examination in serial sections revealed the direct con nection between the carcinoma and the metanephric duct remnant. Moreover, t he remnant epithelium showed varying degrees of dysplastic changes, includi ng carcinoma in situ in close proximity to the carcinoma. This patient also had a bicornate uterus and left renal aplasia. To our knowledge, this is t he first reported case of a primary vaginal adenocarcinoma arising from the metanephric duct remnant. Although the precise mechanism involved in carci nogenesis in this clinicopathological setting remains unknown, adenocarcino ma should be included in the differential diagnosis of vaginal tumors in pa tients with renal aplasia and/or an ectopic termination of the ureter or me tanephric duct remnant, especially when the tumor is in the anterior wall.