No evidence of misdiagnosis in patients with multiple sclerosis and repeated positive anticardiolipin antibody testing based on magnetic resonance imaging and long term follow-up.

OBJECTIVE: To determine whether patients with definite multiple sclerosis (MS) and repeated positive anticardiolipin antibody (aCL Ab) testing fulfil the recently updated criteria for the antiphospholipid syndrome (APS). Also, to determine if these patients form a separate subgroup in terms of long term follow-up and MRI characteristics.
DESIGN: A blinded case control study comparing MRI patterns between aCL Ab positive and negative MS patients with a clinical follow-up of 7 years. PARTICIPANTS: 8 (5.6%; male:female ratio 2:6; 6 relapsing-remitting subtype, 1 primary progressive subtype and 1 neuromyelitis optica (NMO)) of 143 consecutive patients with definite MS or NMO (71% relapsing-remitting, 18% secondary progressive and 6% primary progressive disease course; 4% NMO) showed repeated positive aCL Ab testing.
SETTING: Outpatient clinic of a tertiary MS centre in The Netherlands.
RESULTS: All eight aCL Ab positive patients had levels below 40 MPL/GPL units, with the majority of intervals between tests of at least 12 weeks. After follow-up, none of the patients fulfilled the criteria for APS. No specific MRI features were present compared with 24 matched aCL Ab negative patients.
CONCLUSIONS: No aCL Ab positive MS patient fulfilled the criteria for APS, arguing against a possible misdiagnosis or coexistence.