TFE3-Expressing Epithelioid Rich Perivascular Epithelioid Cell Neoplasm (PEComa) of the Bladder with Unusual Benign Course.

Abstract

Perivascular epithelioid cell tumor (PEComa) is an uncommon tumor which presents with epithelioid and spindled cell morphology and is immunoreactive for myogenic and melanocytic markers. Recently, a subset of PEComas has been reported to harbor <i>TFE3</i> gene rearrangement.In this case report, we describe a <i>TFE3</i>-expressing primary bladder PEComa in a 27-year-old male patient with acute myeloid leukaemia in remission. The tumor displayed epithelioid morphology with surrounding delicate blood vessels and was devoid of a prominent spindle cell component. Malignant features were not identified. The tumor expressed HMB45, CD117, and focal patchy positive expression for SMA. <i>TFE3</i> gene translocation was confirmed by Fluorescence in-situ hybridization. RT-PCR assay confirmed the presence of <i>SFPQ-TFE3</i> gene fusion.In contrast to previously reported aggressive <i>TFE3</i> gene-rearranged bladder PEComa cases, our case shows benign histologic and clinical features. Current clinical follow-up also shows a benign course.