Perivascular epithelioid cell tumor.

Perivascular epithelioid cell tumors are mesenchymal neoplasms defined by the presence of histologically and immunohistochemically distinctive perivascular epithelioid cells. The perivascular epithelioid cell has no known normal tissue counterpart and coexpresses myoid and melanocytic markers. This tumor family shows marked female predominance and includes angiomyolipoma, clear cell sugar tumor, lymphangioleiomyomatosis, and a group of rare, morphologically and immunophenotypically similar tumors arising at a variety of visceral and soft tissue sites. This latter subset has been collectively termed perivascular epithelioid cell tumors-not otherwise specified. They are usually composed of epithelioid, but occasionally spindled, cells with clear to granular eosinophilic cytoplasm and focal perivascular accentuation. The mainstay of treatment is wide excision. Although most cases are benign, a subset behaves in a malignant fashion. Since few malignant cases have been reported, firm criteria for malignancy have yet to be established. This review focuses on the perivascular epithelioid cell tumors-not otherwise specified subset.