The patient initially presented at 18 months of age with self limiting episode of acute disseminated encephalomyelitis. He became symptomatic again at 9 years of age with emotional outbursts, cognitive issues and lack of focus. A few months later, he had an episode of hand stiffening and clenching followed by rhythmic movements of right foot and nystagmus. EEG showed generalized background slowing. MRI brain showed new multifocal T2-hyperintense non-enhancing areas in bilateral cerebral hemispheres. Due to ongoing cognitive issues, a repeat MRI brain was done 3 months later, showing enhancing stippling lesions along prior right frontal white matter lesion, and left hippocampal atrophy. Cerebrospinal fluid analysis showed positive Oligoclonal bands and negative serum Anti- MOG IgG (Cell Based Assay-IFA). Whole genome sequencing and metabolic testing was unrevealing. He continued to have lingering inattention, anxiety and tics. Interval MRI brain showed increased white matter lesions as well as bilateral temporal enhancing lesions. A brain biopsy was performed due to diagnostic dilemma showing perivascular demyelinating process with background reactive gliosis without evidence of vasculitis or infection. He was treated with Rituximab for a possible demyelinating disorder. Repeat MRI brain showed resolution of enhancement with stable T2 hyperintensities at 1 year follow up. Diagnostic uncertainty led to repeat MOG antibody testing, which was positive (MOG IgG1, FACS  1:1000), leading to the diagnosis of L-MOGAD.

L-MOGAD can present with a protracted clinical course, which can mimic leukodystrophies and demyelinating diseases. Rituximab may be considered as a treatment option in this clinical scenario.