Taken together, our results indicate that occult demyelination / axonal injury in periepndymal tissues was more prominent in the periependymal area surrounding the third and fourth ventricles than in lateral periventricular areas in NMOSD patients, and this difference can differentiate NMOSD from MS, reflecting the distribution of AQP-4, which is the key pathology associated with NMOSD. This evidence concerns the gene AQP4 and myeloid sarcoma.