IFNB1 and myeloid sarcoma: Relapsed with left hemiparesis. Brain MRI: small, nonenhancing periventricular and brainstem lesions not fulfilling the 2010 McDonald MRI Criteria for lesion dissemination in time and space. Oligoclonal bands in CSF. Atypical MS diagnosed and patient treated with high‐dose methylprednisolone. IFN‐beta introduced. EDSS 2.5