• Mixed connective tissue disease (MCTD) seems to be a distinct entity that has some manifestations of systemic lupus erythematosus, scleroderma, polymyositis, and Sjögren's syndrome and is serologically characterized by the presence of an antibody to ribonucleoprotein. We report the cases of three children with MCTD with high titers of antibody to ribonucleoprotein. Two fulfilled criteria of lupus erythematosus, two had polymyositis; all three had suggestive features of scleroderma, fulfilled criteria for the diagnosis of juvenile rheumatoid arthritis, and had Sjögren's syndrome. Additional superimposed features of another connective tissue disease should arouse suspicion of MCTD. All three of our patients responded adequately to corticosteroid treatment that makes recognition of this entity by the pediatrician all the more important.
(Am J Dis Child 132:263-265, 1978)