Pediatric-Onset Multiple Sclerosis at Age 10 Following Nephrotic Syndrome: Early Recognition and Successful Treatment With Fingolimod

Pediatric-onset multiple sclerosis before the age of 10 is rare and poses significant diagnostic challenges. We report a 10-year-old boy who developed multiple sclerosis five years after remission of nephrotic syndrome. He presented with progressive left eye visual loss and vertigo. Advanced magnetic resonance imaging (MRI) revealed demyelinating lesions with a central vein sign and paramagnetic rim, emerging biomarkers that support the diagnosis of pediatric multiple sclerosis. Cerebrospinal fluid analysis demonstrated type 2 oligoclonal bands, while anti-aquaporin-4 and anti-myelin oligodendrocyte glycoprotein antibodies were negative. The diagnosis of multiple sclerosis was established according to the 2017 McDonald criteria. Early treatment with fingolimod (0.5 mg daily) resulted in complete clinical and radiological disease suppression over an 18-month follow-up period. This case highlights the value of advanced MRI biomarkers in very early-onset multiple sclerosis, the importance of systematically excluding disease mimics in prepubertal children, and the effectiveness of early initiation of high-efficacy disease-modifying therapy. Early recognition and prompt treatment are essential to optimize outcomes in pediatric multiple sclerosis.