Clinical features of the arthritis of mixed connective tissue disease.

Seventeen of 19 patients with mixed connective tissue disease (MCTD) had arthritis as a significant initial feature of their disease; 8 were given an initial diagnosis of rheumatoid arthritis (RA) and 4 received chrysotherapy. RA-like hand deformities were present in 35% and contractures and/or persistent loss of joint motion in 47%. Joint radiographs showed abnormalities in 41% and included erosions and/or cysts in 30%. The arthritis of MCTD may be both erosive and deforming and this disease should be considered in patients presenting as RA with unusual features.