Spindle cell epithelioma of the vagina shows immunohistochemical staining supporting its origin from a primitive/progenitor cell population

Spindle cell epitheliomas of the Vagina (SCEVs) coexpresses epithelial and mesenchymal markers and were first described as a "mixed tumors of the vagi na." However, unlike mixed tumors of other organs, which are believed to or iginate from myoepithelial cells, SCEVs neither immunohistochemically nor u ltrastructurally show features of myoepithelial cells. The present expanded battery of immunohistochemical stains is presented on this rare tumor, inc luding cytokeratin AE1/AE3, CK7, CK20, S100 protein, epithelial membrane an tigen, alpha -smooth muscle actin, desmin, CD34, CD99, Bcl-2, vimentin, est rogen and progesterone receptors, and Ki-67. There was minimal expression o f alpha -smooth muscle actin and negative staining with S100 protein, with coexpression of cytokeratins and vimentin and expression of estrogen and pr ogesterone receptors, as previously reported in SCEVs. In addition, diffuse expression of CD34, CD99, and Bcl-2 immunohistochemical stains was found, which has not previously been reported. The coexpression of CD34, CD99, and Bcl-2 in SCEVs is consistent with its origin from a primitive/progenitor c ell population.