PEComas: a review with emphasis on cutaneous lesions.

The connection between angiomyolipoma (AML) of the kidney, clear cell sugar tumor (CCST) of the lung, and pulmonary lymphangioleiomyoma (LAM), was progressively discovered because of the histologic and immunophenotypic similarities between the three tumors and their frequent association with tuberous sclerosis complex (TSC). Morphologically, analogous lesions found in other locations are composed of the unifying cell, the perivascular epithelioid cell (PEC). PEC tumors (or PEComas), other than AML, CCST, and LAM, are not associated with TSC and typically occur in middle-aged adult females. These neoplasms are composed of nests and fascicles of clear to granular epithelioid and/or spindled cells with a consistent arrangement around blood vessels. Characteristically, the cells express both melanocytic (usually HMB45) and myogenic (typically actin) markers. Although the most common sites are the gastrointestinal and genitourinary tracts, approximately 23 cases, to date, of PEComas arising in the skin have been reported. Primary cutaneous PEComas also have a predilection for adult females and most often present as a painless mass on the extremities. In contrast to other sites, the myogenic marker most commonly expressed in PEComas of the skin is desmin. Most reported cutaneous PEComas follow a benign course, however, a malignant case has been reported. Surgical excision is currently the mainstay of treatment.