Myoepithelioma-like tumor of the vulvar region: a case report in China and review of the literature

BACKGROUND: Myoepithelioma-like tumor of the vulvar region (MELTVR) is a recently described mesenchymal neoplasm which typically arising in vulvar regions of adult women. CASE PRESENTATION: Here we report a case of a 65-year-old woman who presented with a 6-year history of subcutaneous mass in the vulvar region. The mass had recently increased in size continuously. Histologically, the tumor cells had an epithelioid to spindled shape. Epithelioid tumor cells proliferated singly or in a loosely cohesive manner with myxoid areas, while spindled tumor cells grew in diffuse sheets or storiform arrangements mainly in nonmyxoid areas. Immunohistochemically, the tumor cells were positive for vimentin, epithelial membrane antigen, calponin, and were partially mild to moderate positive for estrogen receptor, but completely negative for S100 protein, glial fibrillary acidic protein, CD34, desmin, SMA and cytokeratin. INI1/SMARCB1 expression was deficient. EWSR1 and FUS genes were intact tested by fluorescence in situ hybridization analysis. Based on these findings, we diagnose this case as MELTVR. The patient remained relapse-free after the lesion was widely excised during 8 months follow-up. CONCLUSIONS: This disease should be included in the differential diagnostic list of vulvar tumors with epithelioid to spindled morphology. Recognition of its histopathological features and immunohistochemical reactivity will help to understand the tumor better.