Extradural spinal arteriovenous fistula mimicking schwannoma: Diagnostic pitfalls and surgical implications

Spinal arteriovenous fistulas are rare vascular lesions that may present with nonspecific clinical and radiological findings, leading to diagnostic challenges. Extradural arteriovenous fistulas, in particular, can mimic more common spinal tumors such as schwannomas. We report a 37-year-old man who presented with progressive low back pain and left lower extremity numbness. Neurological examination revealed hypoesthesia in the L2-L3 dermatomes without motor deficit. Contrast-enhanced lumbar magnetic resonance imaging demonstrated a well-defined, homogeneously enhancing lesion extending from L1-L3 with neural foraminal extension, suggestive of an intradural extramedullary schwannoma. Surgical exploration revealed an extradural vascular lesion with arterialized veins rather than a nerve sheath tumor. The lesion was completely resected following coagulation of feeding vessels, and posterior instrumentation was performed for stabilization. Histopathological examination confirmed the diagnosis of an extradural spinal arteriovenous fistula. Postoperative magnetic resonance imaging and digital subtraction angiography demonstrated no evidence of residual arteriovenous shunting. Retrospective review of the preoperative magnetic resonance imaging identified subtle imaging features that may have suggested a vascular etiology. This case highlights an important diagnostic pitfall and emphasizes the need to consider vascular lesions in the differential diagnosis of enhancing spinal masses, particularly when imaging findings are atypical. Preoperative vascular imaging may aid surgical planning and reduce intraoperative risk.