Perivascular epithelioid cell tumor (PEComa) of the urinary bladder: report of 3 cases and review of the literature.

The perivascular epithelioid cell family of tumors (PEComas) includes familiar lesions such as angiomyolipoma, lymphangioleiomyoma, and clear-cell "sugar" tumors of the lung. Less frequently, PEComas arise in various other locations throughout the body including soft tissue, bone, and visceral organs. We report 3 cases of PEComa arising in the urinary bladder in 2 men in their fourth decade, and 1 woman in her third decade. All 3 tumors showed histologic features characteristic of PEComa including spindled and epithelioid cell morphology with variable clear cell change, and all coexpressed melanocytic and smooth muscle associated markers by immunohistochemistry. Follow-up demonstrated an indolent course for 2 patients with no evidence of disease at 10 and 21 months, respectively, and the third case was recently diagnosed. We also provide a review of the 4 previously reported PEComas occurring in the bladder. PEComas of the urinary bladder should be carefully distinguished from a variety of histologically similar, but clinically dissimilar entities.