Myxoid spindle cell neoplasm with FET::CREB fusion mimicking meningioma: illustrative case.

Background: Myxoid spindle cell neoplasm and meningioma are two different pathologies that can have similar radiographic findings. Despite their benign radiographic appearance, myxoid spindle cell neoplasms are heterogeneous, prone to recurrence, and associated with high mortality.

Observations: The authors present the case of a woman in her late 60s who experienced a witnessed seizure characterized by right arm tonic-clonic movements and subsequent left-sided manifestations. Initial radiographic findings were suggestive of a meningioma, but further investigation revealed a myxoid spindle cell neoplasm with a possible FET::CREB fusion. Pathologically, the tumor expressed desmin, EMA, and CD99, resembling meningiomas histologically.

Lessons: The case highlights the diagnostic challenges of this rare tumor and underscores the need for advanced molecular diagnostics such as next-generation sequencing to guide appropriate management. https://thejns.org/doi/10.3171/CASE25497.