Clear cell 'sugar' tumor (PEComa) of the skin: a case report

The so-called perivascular epithelioid cell neoplasm (PEComa) family includes angiomyolipoma, clear cell 'sugar' tumor (CCST), lymphangioleiomyomatosis, and clear cell myomelanocytic tumor (CCMMT). These rare tumors are characterized by the co-expression of melanocytic and muscle markers. They have been recognized in an increasing number of sites but currently only one case of PEComa, of the CCMMT subtype, has been reported in the skin in abstract form. We provide the clinicopathologic description of a case of extrapulmonary CCST located in the dermis and superficial subcutis of the thigh of a 60-year-old female. The lesion was composed of nests of epithelioid and spindle cells with abundant clear to granular cytoplasm and distinct cell borders. The tumor showed strong and diffuse immunoreactivity with HMB-45. Scattered cells expressed desmin and h-caldesmon. Antibodies to S-100 protein, melan-A, cytokeratins, and smooth muscle actin were negative. This first case of cutaneous PEComa of the CCST type expands the differential diagnosis of clear cell/granular cell tumors of the skin.