Abstract
Juvenile dermatomyositis（JDM）is characterised by diffuse inflammation in muscle and non-infectious
inflammation of skin by systemic small vessel vasculopathy． Polymyositis（PM）is rare in children． The clinical
features of 13 JDM patients and 2 patients， which were 15children（8 boys and 7 girls）and aged between 2
months and 11 years and l l months， were analyzed retrospectively． There were 8 boys and 7 girls． The age at
onset ranged from 2 month to 11 years and 11 month． Rash and muscle weakness were most common as initial
symptoms． Initial treatment was a prednisoline therapy in 3 cases and a methlprednisolone pulse therapy in
llcases．． Combination therapy with intravenous immunoglobulin or methotrexate were done in 5 cases． As
complication， calcinosis in 3 cases， central nervous system symptoms in 1 case， endocrine dysfunction in 2
cases were shown． 1 case showed small intestine ulcer， so it was suspected severe type（Banker type）JDM．2
cases already showed interstitial lung disease with high levels of KL-6 at onset． On severe type JDM and early
onset case（2 month）， it were difficult to reduce dosage of prednisolone and control by combination therapy with
some immunosuppressive drugs． The clinical features of JDM/PM exhibit broad spectrum of the severity． It is
important to select proper treatment on a varied severity of JDM/PM．
