Perivascular epithelioid cell tumor (PEComa) of the urinary bladder associated with Xp11 translocation.

Perivascular epithelioid cell-containing tumors (PEComas) represent a rare family of neoplasms. Their dichotomous phenotypic features, including both myogenic and mylanocytic features, can make a definitive diagnosis difficult. Such tumors have been associated with the overexpression of transcription factor E3 (TFE3). An Xp11 translocation could account for the aberrant activity of TFE3 but has never before been described in affiliation with a PEComa of the urinary bladder. While PEComas of the bladder have exhibited benign clinical courses to date, here we present an intravesical PEComa shown to have an Xp11 translocation and resultant overexpression of TFE3, indicating an aggressive, metastatic nature. No consistent tumor characteristics have proven accurate at identifying aggressive tumors. However, mTOR inhibitors offer a mechanistic management strategy when systemic therapy is warranted.