Vulvovaginal polyps. Histologic appearance, ultrastructure, immunocytochemical characteristics, and clinicopathologic correlations.

A clinicopathologic study of 18 vulvovaginal fibroepithelial polyps with a comparison to normal stroma is presented. Twelve cases were analyzed by immunohistochemical methods for the presence of vimentin, desmin, muscle-specific actin, myoglobin, S-100 protein, alpha 1-antitrypsin (AAT), alpha 1-antichymotrypsin (ACHT), cytokeratin (AE1/AE3), and epithelial membrane antigen. Stromal cells reacted with vimentin antiserum in eight cases. Desmin reactivity was detected in five of 12 cases, four of which coexpressed vimentin. Two cases exhibited muscle-specific actin reactivity, and a single case weak AAT reactivity. The stromal cells were unreactive with S-100 protein, epithelial membrane antigen, cytokeratin, ACHT, and myoglobin. Ultrastructurally, the stromal cells of four fibroepithelial polyps resembled fibroblasts and myofibroblasts. Our immunohistochemical and ultrastructural data suggest that the stromal cells of fibroepithelial polyps are a collection of functional fibroblasts that may be capable of differentiating along two or more cell lines. Dramatically elongated cytoplasmic processes extend from both normal vulvovaginal stromal cells and the cells of the polyps. The cell attachments to each other and to bundles of collagen suggest a potential for a physiologic role in tissue contractility, especially in the immediate postpartum state. The common association with pregnancy may represent a local exuberant response to some presently unidentified trophic or stimulating factor.