First line medications, namely interferon beta (IFNB) and glatiramer acetate (GA), are the standard care of patients with pediatric with MS (ped-MS) [1–3], however about 30 % of them are partial or non-responder to first line treatments requiring a shift to other disease modifying treatments (DMT) [4]. Here, IFNB1 is linked to myeloid sarcoma.