Cystic Schwannoma of the Lumbar Spine Presenting as a Solid Lesion During Surgery: Radiologic-Pathologic Correlation.

Spinal schwannomas are common benign intradural extramedullary tumors that typically present as solid lesions on imaging. However, cystic degeneration may occur and produce atypical radiological features, complicating preoperative diagnosis and differential considerations. We report the case of a 46-year-old woman presenting with a three-month history of left-sided lumbosciatica and intermittent paresthesia without neurological deficit. Magnetic resonance imaging revealed a well-circumscribed intradural cystic lesion anterior to the L4 vertebral body with peripheral contrast enhancement, suggestive of a cystic schwannoma. The patient underwent L3-L4 laminectomy and microsurgical resection. Intraoperatively, the lesion was found to be predominantly solid despite its cystic radiological appearance, highlighting a radiologic-intraoperative discordance. Histopathological analysis confirmed the diagnosis of cystic schwannoma, demonstrating spindle-shaped Schwann cells, myxoid stroma, and focal degenerative changes. The postoperative course was uneventful, with complete symptom resolution and no evidence of residual tumor on follow-up imaging. Cystic schwannomas represent a diagnostic challenge due not only to their heterogeneous imaging characteristics but also to potential discrepancies between imaging and intraoperative findings. The correlation between imaging, surgical findings, and histopathology is essential for accurate diagnosis. This case highlights the importance of considering schwannoma in the differential diagnosis of intradural cystic spinal lesions, even when imaging suggests a purely cystic mass. Complete microsurgical resection remains the treatment of choice and is associated with excellent clinical outcomes.