CRP and vasculitis: Around half of RA patients have extra-articular manifestations, including rheumatoid nodules, vasculitis, or interstitial pneumopathy among others [4], whereas laboratory findings include the presence of the rheumatoid factor in 61%, antibodies anti-cyclic citrullinated peptide in 57%, and elevation of acute phase reactants such as C-reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) [5].