Myoepithelioma-Like Tumor of the Vulva.

Myoepithelioma-like tumor of the vulvar region (MELTVR) is a rare mesenchymal tumor that typically arises in the female vulva. Here, we report a case of a 48-year-old woman who presented with a 2-year history of subcutaneous mass in the vulvar region. As the mass rapidly increased in the last 2 months, personal slight swelling pain appeared. Histologically, the tumor exhibited a distinctive feature of abundant tumor cells and sparse mucus regions. While each region appeared alternately, the sparse mucus region was about 30% of the whole tumor. The tumor had two types of cells, namely, epithelioid and spindle cells. The tumor-rich region demonstrated a cell type of epithelioid, showing hermaphroditic cytoplasm, the center-located nucleus, and abundant chromatin of fasciculate or cord-braid arrangement, whereas the cell of the mucus region was fusiform or epithelioid with partial vacuole-shaped and small visible nucleolus, exhibiting red-stained cytoplasm and loose chromatin. Immunohistochemically, vimentin, smooth muscle actin (SMA), and P16 were diffuse positive in tumor cells, whereas desmin, cytokeratin (CK), P40, P63, CK5, HMB45, MyoD1, myogenin, S100, and SOX10 were all negative. While the proliferation index of Ki-67 was about 7%, the expression of SMARCBl/lNI-1 protein was absent. The pathological diagnosis is myoepithelioma-like tumor of the vulva (right labia majora). Finally, the tumor was surgically and completely removed, and no recurrence or metastasis was found after 6 months of follow-up. Histologically, the morphology of MELTVR is changeable and variation existed for each individual tumor. Moreover, it needs to be differentiated from various other types of tumors, whereas more reports and studies are required to further clarify MELTVR.