Rare presentation of a spinal schwannoma with fluid-fluid level: A case report on radiological features, histopathological correlation, and surgical management.

Spinal schwannomas represent approximately 20%-30% of all spinal tumors and are the most common type of intradural extramedullary tumors. These benign tumors arise from Schwann cells, which myelinate peripheral nerve fibers. Although typically slow-growing and benign, schwannomas can cause significant neurological deficits depending on their location and size. The presence of a fluid-fluid level on magnetic resonance imaging (MRI) in spinal schwannomas is extremely rare, with most reported cases involving vestibular schwannomas of the central nervous system. In this report, we present a 50-year-old female diagnosed with an intradural extramedullary space-occupying lesion (SOL) at the L1-L2 level, demonstrating a fluid-fluid level on MRI. The patient initially presented with low back pain and left-sided radiculopathy along the L5 dermatome, raising suspicion for a prolapsed lumbar intervertebral disc (PLID) at L4-L5. However, MRI revealed an intradural extramedullary lesion at L1-L2, which was further characterized by a fluid-fluid level, suggesting hemorrhagic or cystic degeneration within the tumor. The differential diagnosis included aneurysmal bone cysts, soft-tissue cavernous hemangiomas, and simple bone cysts. Histopathological examination confirmed cystic degeneration and intratumoral hemorrhage, consistent with schwannoma. The tumor was excised en bloc along with its capsule, preserving the surrounding neural structures. This case highlights the importance of considering atypical imaging findings, such as fluid-fluid levels, when diagnosing spinal schwannomas and underscores the need for comprehensive diagnostic evaluations and careful surgical management.