Inflammatory Myelopathy Associated With Clinically Suspected Eosinophilic Granulomatosis With Polyangiitis Treated With Adjunctive Anti– IL ‐5 Antibody Therapy

ABSTRACT Eosinophilic granulomatosis with polyangiitis (EGPA) rarely involves the central nervous system, and spinal cord involvement is particularly uncommon. We report a young woman with clinically suspected EGPA who developed inflammatory myelopathy with persistent neurological deficits despite high‐dose corticosteroid therapy. Cervical magnetic resonance imaging demonstrated longitudinally extensive spinal cord lesions predominantly involving the anterior cord. High‐dose corticosteroids resulted in rapid clinical and laboratory improvement; however, fine motor impairment of the left hand persisted. Anti–interleukin‐5 (IL‐5) therapy was subsequently introduced for relapse prevention and glucocorticoid reduction after initial stabilization, leading to gradual improvement of the residual neurological deficit. Anti–IL‐5 therapy may have contributed to disease control and prevention of eosinophil‐mediated tissue injury. This case highlights a rare manifestation of inflammatory myelopathy associated with clinically suspected EGPA and provides preliminary, hypothesis‐generating insight into the potential adjunctive role of IL‐5–targeted therapy following initial corticosteroid treatment.