TFE3-Rearranged PEComa(-Like Neoplasm) of the Chest Wall Diagnosed by Fine-Needle Aspiration: A Case Report

We report a rare TFE3-rearranged perivascular epithelioid cell tumor (PEComa) of the parasternal chest wall diagnosed preoperatively by fine-needle aspiration (FNA) cytology. The smears and cell block showed epithelioid cells with clear to granular cytoplasm and prominent nucleoli. Immunohistochemistry (IHC) demonstrated strong nuclear TFE3 expression and melanocytic marker positivity (diffuse HMB-45, focal Melan-A) with absent smooth muscle marker staining. FISH confirmed a TFE3 rearrangement, and next-generation sequencing identified an SFPQ:TFE3 fusion. The integrated cytologic and molecular workup enabled definitive classification as a TFE3-rearranged PEComa before surgical resection. This case highlights the diagnostic utility of cytologic material for translocation-associated neoplasms and the importance of molecular subtyping for prognosis and treatment.