Prolonged Fever: An Atypical Presentation in MOG Antibody-Associated Disorders.

Background: Myelin oligodendrocyte glycoprotein (MOG) antibody-associated demyelinating disorders (MOGAD) are increasingly being recognized in the pediatric age group. Over time, unusual presentations have expanded the clinical presentation. We report 12 cases of MOGAD where prolonged fever (PF) was an important part of the symptom complex during the course of the illness.

Methods: After initial recognition of this atypical clinical presentation, more patients were recruited over 2 years and followed up prospectively.

Results: Eight of twelve patients had no clinical/imaging evidence of demyelination until much later in the course. Three clinical presentations recognized were fever of unknown origin (4 of 12), aseptic meningitis (4 of 12), and PF seen concurrently with established acute demyelination syndrome (4 of 12). Leukocytosis, raised inflammatory markers, and cerebrospinal fluid pleocytosis were almost universal. The first two presentations frequently caused diagnostic confusion, as MOGAD was not considered until several weeks after disease onset. The third group was more a therapeutic conundrum on how to manage the PF. Early seizures without encephalopathy were not uncommon and were probably independent of the later-appearing demyelination.

Conclusions: This case series highlights PF as an important component of the pediatric MOGAD symptom complex. MOGAD could be considered in the differential diagnosis of these clinical presentations.