Uncommon alliance between MOGAD and Behçet's disease.

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is a newly recognized demyelinating disease with diverse clinical and radiological manifestations that continue to expand over time. Its coexistence with Behçet's disease, a multisystem inflammatory disorder, has not been previously reported. We report a rare case of a 40-year-old female with Behçet's disease who was treated with colchicine and developed two attacks of longitudinal extensive transverse myelitis, associated with positive serum anti-MOG antibodies. During the first episode, the patient responded well to five days of intravenous methylprednisolone associated with two plasma exchange sessions. Although recommended, the patient declined Mycophenolate Mofetil treatment until the second episode. Since then, she has remained free of relapses during two years of follow-up, reinforcing the hypothesis that a background of autoimmune dysregulation may predispose patients to MOGAD and lead to its recurrence.