AQP4 and erythema multiforme: However, NEMOS strongly recommends that AQP4-IgG-negative patients who meet the criteria for MOG-EM/MOGAD [77, 78] should no longer be assigned the diagnosis of NMOSD, as convincing evidence now suggests that MOG-EM/MOGAD is a pathogenetically, clinically, and prognostically distinct disorder in its own right, possibly with different treatment needs [75, 77, 78, 84, 86, 154].