Intracranial Mesenchymal Tumor With Rare EWSR1::CREM Gene Fusion in an Older Adult Woman: A Case Report and Review of the Literature.

Intracranial mesenchymal tumor with EWSR1::CREM fusion represents a rare molecular subtype of FET::CREB fusion-positive neoplasms, provisionally recognized in the 2021 WHO Classification of Tumors of the Central Nervous System. These non-meningeal, primary intracranial tumors exhibit a broad histomorphologic spectrum and uncertain histogenesis; outcome data remain limited, yet their distinctive localization and unique histology warrant continued study. We analyzed 26 EWSR1::CREM fusion-positive patients, comprising 25 from the literature and one new patient-a 60-year-old woman with a history of breast carcinoma who presented with a right frontal mass. Histology demonstrated classic stellate/spindle cell morphology, abundant myxoid stroma, and positivity for EMA, CD99, desmin, and CD163. Following gross-total resection, she remains disease-free at 17 months, representing the second-oldest reported patient to date.