Clinical analysis of 11 cases of juvenile dermatomyositis and polymyositis

: Juvenile dermatomyositis (JDM) is characterized by microvasculopathy of the striated muscle, which indicates different etiology, clinical manifestation and prognosis from the adult-onset dermatomyositis. We experienced 10 cases of JDM and 1 case of juvenile polymyositis (JPM) in the recent 14 years, and analyzed clinical manifestation, laboratory findings, treatment anrognosis. The cases were 9 girls and 2 boys. The onset of the disease was 2 years of age in 2 patients, and 9 to 13 years of age in 9 patients. During the follow-up courses, no cases were dead or complicated with neoplasm. Skin rash was the most frequent manifestation at the onset, and facial erythema was common. Muscle weakness was observed only in 4 cases at the onset, and in all cases muscle enzymes including creatine kinase and aldolase were elevated. The clinical course was classified into three groups; monocyclic (5 cases), chronic and recurrent (4 cases), and fulminant (2 cases). Prognosis depended not on the degree of the elevated serum muscle enzymes, but on the initial therapy employed at the onset of the disease. Five cases including 2 cases of fulminant type were initially treated with methylprednisolon pulse therapy, and all of these had no recurrence. On the other hand, 6 cases were started the therapy with p.o. prednisolone. Four of them had frequent recurrences in accordance with tapering of prednisolone. These cases were effectively treated with the combination with immunosuppressants. In previous reports, JDM and JPM were reported to be a disorder which had relatively favorable prognosis. But we found that one third of the cases had chronic and recurrent courses. Methylprednisolone pulses as initial therapy may be effective in preventing the chronicity and recurrence of the disease.