Double Anti‐NMO and Anti‐MOG Positivity in a Patient With Metastatic Renal Carcinoma: First Reported Case

Background: Neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein-associated disease (MOGAD) are central nervous system (CNS) demyelinating disorders characterized by autoantibodies targeting aquaporin-4 (AQP4) and MOG, respectively. Although dual positivity for AQP4-IgG and MOG-IgG antibodies is uncommon, it poses significant diagnostic and therapeutic challenges due to its complex clinical features and uncertain prognosis. Case Presentation: We present the first reported case in the literature of a patient with metastatic renal carcinoma who tested positive for both AQP4 and MOG antibodies. A 49-year-old man with a history of metastatic renal carcinoma experienced progressive neurological symptoms, initially attributed to tumor progression. However, after further investigation, including lumbar puncture and autoantibody testing, a demyelinating process with dual seropositivity for AQP4-IgG and MOG-IgG was identified. Treatment and Outcomes: The patient was treated with high-dose corticosteroids, followed by rituximab, resulting in clinical and radiological stability. Conclusion: This case highlights the rare occurrence of dual seropositivity for AQP4 and MOG antibodies in a patient with a history of metastatic renal carcinoma, which poses diagnostic and treatment challenges. Although the pathogenesis remains unclear, factors such as genetic predisposition and autoimmune coactivation may contribute to triggering this autoimmune response. This case emphasizes the importance of personalized treatment and the need for further research to optimize management strategies for patients with this complex condition.