Imaging Mimics: A Case of Nearly Mistaken Identity with Tumefactive Multiple Sclerosis and X-linked Adrenoleukodystrophy (5135)

Objective: Pediatric demyelinating diseases can present similarly but have different etiologies requiring distinct therapies, leaving practitioners to rely heavily on imaging to guide initial treatment. We describe a patient whose symptoms, age, gender, and imaging were consistent with cerebral X-linked adrenoleukodystrophy (ALD) and was considered for bone marrow transplantation (BMT). However, complete evaluation led to a diagnosis of multiple sclerosis. Background: A 13 year old male presented with subacute bilateral vision loss and difficulty in school. Brain MRI demonstrated bilateral, symmetric, and confluent T2 signal abnormalities involving the corpus callosum, peritrigonal, and occipital white matter, with peripheral diffusion restriction and enhancement consistent with ALD. Very long chain fatty acids, adrenocorticotropic hormone, and cortisol levels were normal on initial and repeat testing. ABCD1 gene evaluation demonstrated no mutations. Whole genome testing showed no pathogenic variants. Repeat imaging was again consistent with ALD. Other autoimmune, neoplastic, and infectious etiologies were considered, but testing was non-diagnostic. To clarify the discrepancy between imaging and ALD biomarkers, and consideration for BMT, brain biopsy was performed. Pathology was consistent with an active inflammatory demyelinating process, and genetic testing was negative for tissue mosaicism of the ABCD1 gene. Given negative ALD workup and concern for a neuroinflammatory process, he was empirically treated for acute disseminated encephalomyelitis with steroids and IV immunoglobulins, after which his vision normalized. Soon thereafter, he had two relapses, leading to a diagnosis of tumefactive multiple sclerosis. Natalizumab was started with stable disease as of this submission. Design/Methods: NA Results: NA Conclusions: Pediatric demyelinating disorders are frequent mimics of multiple neurologic diseases, many of which require prompt treatment. This case highlights the importance of maintaining a broad differential and workup in approaching abnormal imaging. Timely and appropriate treatment in aggressive neuroinflammatory demyelinating disorders is essential for long-term outcomes and empiric treatment should be considered once contraindicated diagnoses are eliminated. Disclosure: The institution of an immediate family member of Dr. Liu has received research support from NIH. Dr. Wright has nothing to disclose. Terry Jessop has nothing to disclose. Dr. Bonkowsky has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Bluebird bio. Dr. Bonkowsky has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Autobahn. The institution of Dr. Bonkowsky has received research support from NIH. An immediate family member of Dr. Bonkowsky has received intellectual property interests from a discovery or technology relating to health care. Dr. Bonkowsky has received publishing royalties from a publication relating to health care.