Neurosyphilis, MOGAD or both? A case of meningoencephalomyelitis associated with MOG-IgG seropositivity in a patient with syphilis

Onset of MOG-IgG associated disease (MOGAD) may often occur following an infectious prodrome. Herein we present a case of a man with latent syphilis who developed meningoencephalomyelitis shortly after initiation of treatment with penicillin. He was initially treated for neurosyphilis without significant improvement, and was ultimately found to be seropositive for MOG-IgG, with marked clinical improvement following treatment with high-dose corticosteroids and plasma exchange. This case raises the possibility that syphilitic infection could be a trigger of MOGAD and underlines the importance of searching for alternative etiologies in patients with presumed neurosyphilis with poor response to antibiotic treatment.