Vaginal tubulovillous adenoma: a clinicopathologic and molecular study with review of the literature.

Vaginal villous or tubulovillous adenomas (TVA) are uncommon tumors histologically similar to their intestinal counterparts. After reviewing the literature, we report the eighth case of TVA, which presented as a polypoid tumor in the vagina, at suburethral level, in a 19-yr-old woman with Arnold-Chiari type II malformation and a myelomeningocele at birth. The tumor consisted of long villi lined by columnar cells with brush borders, pseudostratified nuclei, and foci of high-grade atypia. Immunohistochemistry was positive for cytokeratin 7, estrogen and progesterone receptors, CA19.9, p16, p53, and Ki-67 (53%), with a normal membranous pattern for β-catenin, but negative for cytokeratin 20, CDX2, carcinoembryonic antigen, chromogranin A, and synaptophysin. Neither human papillomavirus nor mutations in the K-RAS, BRAF, or LKB1/STK11 genes were detected. Although a rare neoplasm, awareness of this tumor is important as it must be distinguished from colonic adenocarcinoma or other malignant or benign conditions. The existence of 2 previously reported malignant cases merging with TVAs, and the presence of foci of high-grade dysplasia (p53-positive) in the present case, support TVA as a premalignant lesion.