Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) characterised by multifocal areas of demyelination in the white matter of the brain and spinal cord. Autoantibodies, for example antinuclear antibodies, can also be present. MS and other demyelinating processes, such as transverse myelitis and optic neuritis (which may be clinically isolated cases or be part of the clinical spectrum of MS), are sometimes difficult to differentiate from CNS involvement in systemic autoimmune diseases like systemic lupus erythematosus (SLE), antiphospholipid syndrome (APS), Sjoegren's syndrome (SS), and Adamantiades-Behcet disease (BD). An acute isolated neurological syndrome presents the biggest diagnostic problem, since it is common in MS, but can also be the only feature or first manifestation in SLE, APS, SS, and BD. Indeed, the clinical presentation and lesions evidenced by magnetic resonance imaging may be similar.