Perivascular epithelioid clear cell tumor of the common bile duct.

The perivascular epithelioid clear cell tumor (PEComa) has been described in a number of locations, including the pancreas, uterus, bladder, prostate, and gastrointestinal tract. We report the existence of a similar tumor occurring in the distal common bile duct of a 51-year-old man admitted for obstructive jaundice. The tumor had characteristic histologic features of a PEComa, including a richly vascular organoid architecture, tumor cells with clear to lightly eosinophilic cytoplasm, and variably prominent nucleoli. Immunohistochemically, the tumor cells were positive for HMB-45 and neuron specific enolase but negative for epithelial markers, smooth muscle markers, other neuroendocrine markers, vimentin, melan-A, and S-100 protein. PEComas appear to be ubiquitous tumors with characteristic histology and immunophenotype. Although most of these tumors have behaved in a benign fashion, they should be considered tumors of uncertain malignant potential given previous reports of recurrence and metastases. During a short follow-up period following a conservative local excision, our patient remains free of disease.