A Rare Case of Balo Concentric Sclerosis, a Subtype of Tumefactive Multiple Sclerosis, in a 40-Year-Old Male: Case Report.

Balo concentric sclerosis (BCS) is a rare sub-variant of multiple sclerosis (MS), a demyelinating disease affecting the CNS. BCS is considered a disease of the brain's white matter with a characteristic tumefactive ring signified with alternating myelinated and demyelinated layers, which gives it an "onion-ring" appearance. Our patient is a 40-year-old male with a past medical history (PMH) of human papillomavirus (HPV) who presented to the hospital with acute onset of progressive horizontal diplopia in the left eye and mild right-sided facial weakness and sensation of heaviness in the head. After ruling out stroke, the patient's clinical presentation prompted further investigation with MRI, MR spectroscopy, and an oligoclonal bands' panel. MRI imaging showed a concentric bullseye area of T1 low signal intensity in the left parietal lobe with surrounding edema vasogenic ring enhancement. MR spectroscopy showed a sequence of incomplete ring-enhancing lesions demonstrating a lactate peak and increased choline. The oligoclonal bands' panel, which revealed negative oligoclonal bands, had elevated IgG in the CSF. The patient was diagnosed with BCS based on the clinical presentation, MRI, MR spectroscopy, and oligoclonal bands' panel findings. The patient was started on high doses of methylprednisolone, which improved his symptoms within 24-48 hours of the initial dose.