Primary extrarenal Wilms' tumor of the uterus presenting as a cervical polyp

Extrarenal Wilms' tumor is rare in any site, and only three cases arising within the uterus have been reported. Two of the previous cases were in adolescent girls, appearing as polypoid vaginal masses, and the third was in a 22-year-old woman who had menometrorrhagia. An extrarenal Wilms' tumor in an 11-year-old girl that initially appeared as a 10-cm polyp protruding through the cervix is described. Triphasic differentiation with mesenchymal stroma showing rhabdomyoblastic differentiation both morphologically and immunohistochemically was demonstrated. Epithelial differentiation with focal glomerular differentiation also was present. Most of the primary tumor and almost the entire recurrent tumor were composed of blastemal cells. The diagnosis of an extrarenal Wilms' tumor should be entertained when examining a polypoid tumor of the cervix or a polypoid mass within the vagina in an adolescent patient.