A Rare Case of Susac's Syndrome Masquerading as Progressive-Relapsing Multiple Sclerosis.

Susac's syndrome (SS) is a rare, autoimmune-mediated vasculitis involving central nervous system (CNS) microvasculature, which typically targets the brain, retina, and cochlea. The disease pathology in these regions produces the characteristic triad of encephalopathy, visual loss, and hearing loss. Unfortunately, less than 20% of cases present as the full triad, often making diagnosis challenging. Diagnosis is also confounded by the similarity in the clinical presentation of multiple sclerosis (MS), with an overlap also seen in laboratory studies and radiographic imaging. In this report, we present a case of SS in a young and previously healthy adult male that was initially mistaken as MS. We review the characteristics of SS and highlight the key differences between the two diseases that can be used by diagnosing physicians. Lastly, we describe the treatment strategies involved in SS compared to MS.