AQP4 and myeloid sarcoma: While clinically silent spinal cord lesions may be present in all three conditions during acute attacks, an accumulation of silent spinal cord lesions on T2-weighted imaging/fluid-attenuated inverse recovery MRI performed during remission (i.e., outside of a relapse and at least 3 months from the last attack), a characteristic feature used in the diagnosis of MS [207], was mostly absent in NMOSD (4%) in a large, mixed adult and pediatric AQP4-IgG-positive cohort in the UK) [21], as well as in MOG-EM/MOGAD (0%) in the same study [21].