Epithelioid trophoblastic tumor metastatic to the vagina: An immunohistochemical and ultrastructural study

We describe an epithelioid trophoblastic tumor (ETT) metastatic to the vagi na in a 30-year-old Japanese woman. A polypoid tumor in the vaginal orifice was composed of nests of intermediate trophoblastic cells that showed a st riking epithelioid appearance. In the hysterectomy specimen, a tumor infilt rated through the myometrium and showed histologic findings similar to thos e of the vaginal tumor. The tumor cells were positive for cytokeratin, inhi bin-ol, and melanoma cell adhesion molecule (Mel-CAM, CD146) but were only focally positive for human placental lactogen. Electron microscopic examina tion revealed bundles of well-developed, intermediate-type filaments surrou nding the nuclei.