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

## TL;DR

A patient with metastatic kidney cancer showed rare dual antibodies linked to CNS demyelination, requiring tailored treatment.

## Contribution

First reported case of dual anti-NMO and anti-MOG positivity in a metastatic renal carcinoma patient.

## Key findings

- Patient with metastatic renal carcinoma tested positive for both AQP4–IgG and MOG–IgG antibodies.
- Treatment with corticosteroids and rituximab led to clinical and radiological stability.
- Dual positivity poses diagnostic and therapeutic challenges, suggesting a need for personalized approaches.

## Abstract

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.

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.

The patient was treated with high‐dose corticosteroids, followed by rituximab, resulting in clinical and radiological stability.

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.