Clinical features of patients with juvenile onset mixed connective tissue disease: analysis of data collected in a nationwide collaborative study in Japan.

OBJECTIVE: To analyze the clinical features and outcome of juvenile-onset mixed connective tissue disease (MCTD).
METHODS: Clinical and laboratory findings were compared in 2 groups of MCTD patients divided according to age at onset: juvenile onset: under 16 yrs: adult onset: 16 yrs or older).
RESULTS: Systemic lupus erythematosus-like symptoms, such as facial erythema, photosensitivity. LE cells, lymphadenopathy, and cellular casts, were more frequent in juvenile onset MCTD than in the adult form of the disease. On the other hand, scleroderma-like symptoms, such as esophageal hypomotility, scleroderma-like lesions evident on skin biopsy, pulmonary involvement, proximal scleroderma, and pitting scars, were less frequent in juvenile onset MCTD than in the adult form. Patients with juvenile onset MCTD more frequently met the classification criteria for systemic lupus erythematosus (SLE) and less frequently met those for progressive systemic sclerosis (SSc), compared to patients with adult onset MCTD. At disease onset, hand edema and stiffness were observed less frequently in juvenile onset MCTD than in the adult form. Furthermore, the mortality rate was lower in the former than in the latter (2.8% vs 8.4%).
CONCLUSION: Although previous studies have reported severe symptoms and adverse outcome for juvenile onset MCTD, we conclude from this nationwide study in Japan that patients with juvenile onset MCTD exhibit more SLE-like and fewer SSc-like features and have a relatively favorable outcome.