Perivascular Epithelioid Cell Tumor of the Lung With a Novel YAP1::TFE3 Fusion.

Perivascular epithelioid cell tumor (PEComa) belongs to a family of rare mesenchymal neoplasms that share characteristic morphologic, immunohistochemical and molecular findings. In this report, we provide a detailed clinicopathological characterization of a PEComa incidentally discovered in the right lung of a 53-year-old woman. This tumor with epithelioid cell morphology and myomelanocytic differentiation demonstrated a TFE3::YAP1 fusion by targeted RNA sequencing. While a subset of PEComas shows TFE3 rearrangements, fusion with YAP1 has not been systematically documented in this entity. Clear cell stromal tumor of the lung and epithelioid hemangioendothelioma characteristically display the TFE3::YAP1 fusion; however, as currently defined, both lack myomelanocytic features. Here, we describe a novel TFE3 fusion partner that further expands the spectrum of molecular alterations seen in PEComa.