Atypical Multiple Sclerosis with Antibody to MOG

We report a case of a young female who had magnetic resonance imaging (MRI) brain lesions typical of multiple sclerosis (MS) with cerebrospinal fluid (CSF) oligoclonal bands (OCBs) and definite multiple sclerosis based on revised McDonald criteria; however, she also had atypical features of mild pleocytosis, brainstem and cerebellar peduncle involvement apart from opticospinal (OS) involvement. She also turned out to be positive for anti-myelin oligodendrocyte glycoprotein (MOG) antibody; hence, she was diagnosed with atypical multiple sclerosis. This case highlights when to suspect atypical MS and its management approach.

Typical MS cases are largely anti-MOG-negative. In a study of 50 Japanese cases, with anti-aquaporin 4 (AQP4)-immunoglobulin (IgG)-negative OSMS, just 2 were MOG-IgG-positive, but they had some features atypical for MS, such as bilateral optic neuritis, longitudinally extensive transverse myelitis, or moderate pleocytosis. In another study, antibodies to MOG were found in about 5% (5/104) of preselected adult patients with MS. Patients with MS with antibodies to MOG showed typical MS lesions on brain MRI with concomitant severe brainstem and spinal cord involvement and had a severe disease course with high relapse rates.

In conclusion, any patient showing typical MS lesions on brain MRI with OCB present in CSF but has atypical features like mild pleocytosis with brainstem, cerebellar, or OS involvement should also be tested for autoantibodies to MOG, and if positive, then he/she would require aggressive treatment approach in the form of plasma exchange, if resistant to pulse steroid therapy, followed by either rituximab or natalizumab rather than trying other disease modifying therapies (DMTs).