<b>Tumefactive Relapsing-Remitting Multiple Sclerosis in A 42-Year-Old Male: A Case Report</b>

Background: Tumefactive multiple sclerosis (TMS) is a rare variant of multiple sclerosis (MS) characterized by acute, tumor-like demyelinating lesions in the central nervous system (CNS). This feature can closely mimic intracranial space-occupying lesions, including CNS neoplasms and abscesses, thereby posing significant diagnostic challenges. We report a case of TMS in a 42-year-old male. Case presentation: A 42-year-old male presented with an 8-month history of relapsing and remitting neurological deficits, including tetraparesis, sensory disturbances, impaired consciousness, facial (CN VII) and hypoglossal (CN XII) nerve palsies, and nonfluent aphasia. Cerebrospinal fluid analysis revealed elevated protein levels and inflammatory markers, including interleukin (IL)-6, IL 10, soluble IL-2 receptor (sIL-2R), with negative anti-aquaporin-4 (AQP4) and antimyelin oligodendrocyte glycoprotein (MOG). Initial brain magnetic resonance imaging (MRI) revealed multiple contrast-enhancing white matter lesions with incomplete ring enhancement. Although his symptoms improved following treatment with high-dose intravenous (IV) methylprednisolone, his symptoms subsequently relapse. Repeat MRI showed regression of most lesions, and a new spinal lesion at the C2–C4 level. He was diagnosed with tumefactive relapsing-remitting multiple sclerosis (RRMS) and received another course of high-dose IV methylprednisolone, followed by the initiation of mycophenolate mofetil therapy. Conclusions: This case highlights the importance of considering TMS in the differential diagnosis of patients presenting with large, contrast enhancing brain lesions, even when clinical features are not typical of multiple sclerosis.