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Case Reports

Abstract

Perivascular epithelioid cell tumor (PEComa) is an umbrella term encompassing a group of mesenchymal tumors composed of perivascular epithelioid cells (PECs) which express both smooth muscle and melanocytic markers. Tumorigenesis of the PEComas is predominantly caused by mutations in TSC1/2 genes which makes the tumor amenable to treatment with mTOR inhibitors.  TFE gene rearrangements are reported in a subset of PEComas which do not show alterations in TSC1/2 and thus are not responsive to mTOR inhibitors. We present a case of a PEComa of the mid-foot in a 31-year-old female patient which was found to harbor a novel oncogenic FUBP1:: TFE3 rearrangement. This case expands the fusion landscape of TFE3-rearranged PEComas with a novel fusion and thus reenforces the molecular dichotomy between TFE3-rearranged and TSC1/2-inactivated PEComas. Given the therapeutic implications of varied molecular derivers of PEComas, it is imperative to review the current classification scheme of PEComas. This submission would contribute to a better understanding of the molecular underpinnings of tumorigenesis in PEComas and help to further clarify the clinicopathologic spectrum of TFE3 rearrangements and potential prognostic impact of FUBP1:: TFE3 fusion.