Overlapping connective tissue diseases in children.

Of 18 children with different connective tissue diseases four were found to have overlaps. Two presented features of SLE and PSS or SLE and PM and 2 had features of SLE, PSS and JRA. In two of them antiribonucleoprotein antibodies were detected by radical immunodiffusion. But these antibodies were also detected in a few children suffering from a single connective tissue disease. On the other hand, the six children with anti-RNP were not characterized by a particular clinical picture or a better prognosis; when compared to adults, no significant difference could be observed except that the Raynaud phenomenon, sausage fingers and myositis seemed less frequent in childhood. It may be concluded that combinations of connective tissue disease can occur in children but anti-RNP does not appear as a good biological marker.