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Background: MOG antibody disease (MOGAD) presents along a spectrum including acute disseminated encephalomyelitis, transverse myelitis, and optic neuritis. Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is rare and may complicate accurate MOGAD diagnosis. This is in part due to a lack of diagnostic criteria for CLIPPERS as well as overlapping clinical and imaging features with MOGAD.

Case Report: We report a case of a 63-year-old with monophasic optic neuritis due to MOGAD initially misclassified as CLIPPERS. The patient was seropositive for MOG-ab and responded well to high-dose corticosteroids tapered over 9-months. Ocular mobility, visual field, and vision were noted to improve, with no new symptoms developing. Vision remains stable two years following initial presentation, despite a recurrent episode of ON after 18-months. Steroid responsiveness supports a MOGAD diagnosis.

Discussion: In adults with MOGAD, ON is the most common neurological symptom and typically involves the anterior optic pathway. Symptoms are often bilateral and result from optic nerve inflammation and optic nerve lesions.  CLIPPERS presents with pontocerebellar dysfunction. MOGAD and CLIPPERS have distinct biological origins and responsiveness to steroids, should not be relied upon as a single means of diagnosis. Disease-specific antibodies are the diagnostic standard. MRI patterns of MOGAD include hyperintensities of the anterior portions of the optic nerve. Characteristic imaging patterns with CLIPPERS include punctate gadolinium enhancement within the pons. MOGAD, however, may also cause pontine lesions and thus is a better unifying diagnosis in the presence of ON and MOG-ab seropositivity.  

Conclusion: This case underscores the importance of utilizing disease-specific antibody testing in patients who present with optic neuritis. MOGAD should be included in the differential diagnosis for these patients. Antibody testing, diagnostic imaging, steroid responsiveness, history of present illness, and the extent of existing disability may provide a complete diagnostic picture.