TFE3 Gene Rearrangement in Perivascular Epithelioid Cell Neoplasm (PEComa) of the Genitourinary Tract.

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms with unpredictable behavior. They are characterized by epithelioid cells, which stain with melanocytic markers, associated with spindle cells reactive for smooth muscle markers. PEComas may be sporadic or associated with the tuberous sclerosis complex, with mutations affecting mostly tuberous sclerosis complex (TSC) 2 and less frequently TSC1 genes. More recently a subtype of PEComa harboring TFE3 gene rearrangement, mutually exclusive with TSC complex mutations, has been identified. The bladder and the other genitourinary tract organs are an infrequent site of origin; to date, only 3 cases of primitive bladder PEComas, 1 prostatic PEComa, and 2 epithelioid angiomyolipomas of the kidney with TFE3 rearrangement have been described in literature. We report a bladder PEComa case with Xp11 rearrangement in a patient who previously had undergone chemotherapy for chronic lymphatic leukemia. We assessed the meaning of the presence of TFE3 rearrangement in genitourinary tract PEComas and the possible correlation of these uncommon lesions with previous chemotherapy. A better understanding of this entity's genetics may help suggest appropriate targeted therapy, which is still lacking in genitourinary tract PEComas.