Follow-Up of Neurosarcoidosis With Longitudinally Extensive Myelitis: A Case Report and Review of the Literature.

A 49-year-old woman presented with a three-month history of neuropathic pain and paresthesia affecting the trunk and all extremities, accompanied by hypesthesia in the upper thoracic region and both thighs. Spinal MRI revealed a longitudinally extensive lesion spanning 12 vertebral segments (C6 to Th10) with dorsal subpial gadolinium enhancement and a characteristic trident sign on axial images. Cerebrospinal fluid (CSF) analysis showed mild lymphocytic pleocytosis and elevated protein and lactate levels. While aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) antibodies were negative, a significantly elevated concentration of soluble interleukin-2 receptor (sIL-2R) in the CSF (96.1 U/mL; normal <8 U/mL) supported the diagnosis of neurosarcoidosis. Additional findings, including a frontobasal leptomeningeal lesion on brain MRI and enlarged mediastinal lymph nodes, further supported the diagnosis. Treatment with weight-adjusted corticosteroids resulted in rapid clinical improvement and a reduction in MRI enhancement. Four months after treatment initiation, the spinal lesion showed almost complete resolution of gadolinium enhancement and disappearance of the trident sign. Methotrexate was introduced to reduce steroid dependency, resulting in sustained symptom control. Over a four-year follow-up, the patient remained neurologically stable, with no significant MRI findings and normalization of CSF sIL-2R levels. This case highlights the importance of recognizing spinal neurosarcoidosis as a rare but treatable cause of longitudinally extensive transverse myelitis and treating it with appropriate short- and long-term immunosuppressive therapy, especially in patients with significant inflammation. It also highlights the usefulness of MRI and CSF sIL-2R monitoring for diagnosis and long-term treatment.