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038 Adult-onset leukoencephalopathy with neuroaxonal spheroids and pigmented glia mimicking systemic lupus erythematosus cerebral vasculitis

Introduction We present an unusual case of adult-onset leukoencephalopathy with neuroaxonal spheroids and pigmented glia (ALSP) mimicking systemic lupus erythematosus (SLE) cerebral vasculitis. ALSP is an autosomal dominant progressive leukodystrophy, associated with mutations in the CSF1R gene, which induce dysregulation of microglia. The case was compiled from records of clinical data, imaging, brain biopsy and genetic studies. Case A 56 year old previously high functioning man of Southern Chinese origin was hospitalised with recurrent seizures. He had a prior 4 year history of progressive neuropsychiatric features, and 1 year of cognitive decline and occasional falls. Within the year prior, he had positive SLE serology and a renal biopsy consistent with lupus nephritis treated with steroids, mycophenolate, hydroxyl-chloroquine, and later rituximab due to concerns of evolving cerebral vasculitis on cerebral MRI and SPECT scan with MoCA of 20/30. Examination after seizure therapy revealed hyperreflexia, fine tremor, myoclonus, pseudobulbar affect, ideomotor apraxia and slow, independent gait. RUDAS was 6/30 with perseveration. CSF examination and SLE serology were quiescent. Consecutive brain MRIs showed multiple regions of worsening high T2/FLAIR signal in the corpus callosum and supra-tentorial white matter with persistent restricted diffusion. IV steroids and cyclophosphamide were added. Following treatment unresponsiveness, a frontal lobe brain biopsy demonstrated white matter gliosis with prominent axonal spheroids consistent with a primary leukoencephalopathy, with no inflammation, vasculitis nor infection. Immunotherapy was weaned. Genetic testing confirmed a positive CSF1R mutation (c.2329C>T; p. Arg777Trp in Exon 18). A positive family history of dementia in the patient’s elderly mother overseas was identified. The patient remained mobile but mute, and fatally aspirated 8 months after final presentation. Conclusion This report illustrates an unusual presentation of ALSP, initially misdiagnosed as SLE vasculitis. Clinicians should consider an adult onset leukodystrophy and proceed to biopsy and CSF1R gene testing early in suspected ‘refractory cerebral vasculitis’.