Spinal subependymoma mimicking an intradural extramedullary tumor: illustrative case

Spinal subependymomas are rare, benign tumors that typically arise within the spinal cord and usually appear as intramedullary lesions on MRI. The authors report a rare case of cervical spinal subependymoma with exophytic growth that mimicked an intradural extramedullary tumor on MRI.

A 53-year-old man presented with right-sided paresthesia. MRI revealed a spinal tumor causing marked spinal cord compression. The lesion was isointense on T1-weighted images, slightly hyperintense on T2-weighted images, and showed no gadolinium enhancement. A focal CSF cleft between the tumor and spinal cord led to a preoperative diagnosis of an intradural extramedullary tumor, and schwannoma was suspected. However, intraoperative pathological examination suggested a low-grade glioma, prompting a change in the surgical strategy. Subtotal resection was therefore performed to preserve neurological function. Histological examination subsequently confirmed the diagnosis of subependymoma.

Spinal subependymoma may rarely present with an apparent intradural extramedullary appearance on MRI. The presence of a CSF cleft and exophytic growth should not exclude an intramedullary origin. Awareness of this atypical presentation and avoidance of anchoring bias are essential for appropriate intraoperative decision-making. When subependymoma is suspected, maximal safe resection should be prioritized over aggressive tumor removal to preserve neurological function. https://thejns.org/doi/10.3171/CASE26728.