Malignant perivascular epithelioid cell tumor of the oropharynx with strong TFE3 expression mimicking alveolar soft part sarcoma: a case report and review of the literature.

Perivascular epithelioid cell tumors (PEComas) in the head and neck region are rare, with 26 cases described in literature. These distinct mesenchymal tumors normally express both myoid and melanocytic markers. We here report an interesting and challenging case of malignant PEComa that showed transcription factor E3 (TFE3) protein expression and rearrangement, paucity of muscle and melanocytic marker expression, and morphologically mimicked alveolar soft part sarcoma. Awareness of this morphologic pitfall and recognition of TFE3 gene-rearranged PEComa, as a distinct subtype of PEComa, is essential to avoid misdiagnosis.