A Case of Pediatric-onset Mixed Connective Tissue Disease Presenting Raynaud's Phenomenon Affecting Tongue, Hands, and Feet

Mixed connective tissue disease (MCTD) was first described by Sharp and coworkers in 1972, characterized by symptoms of Raynaud's phenomenon or swollen hands, overlapping clinical features of systemic lupus erythematosus, systemic sclerosis, or polymyositis/dermatomyositis, and the presence of anti-U1 RNP antibody. MCTD is rare in children and constitutes 0.3~0.6% of all rheumatologic patients in pediatric rheumatology database of the United States. Here, we report the first Korean case of a 10-year-old female patient with MCTD, presenting Raynaud's phenomenon in the hands, feet, and tongue.