Juvenile dermatomyositis in Thai children

Juvenile dermatomyositis is a rare, chronic multisystemic inflammatory disorder of unknown etiology, characterized by a typical skin rash and proximal muscle weakness. A retrospective study from the medical records of patients diagnosed as juvenile dermatomyositis was performed at Queen Sirikit National Institute of Child Health from 1988 to 1998. There were seven cases of juvenile dermatomyositis diagnosed according to the criteria of Bohan and Peter. Six cases were female and one case was male. The age of diagnosis ranged from 2.5 years to 11 years. (mean age was 7 +/- 3.6 years). The presenting symptoms were muscle weakness (6 cases), muscle pain (2 cases) and skin rashes (4 cases). All of the patients developed proximal muscle weakness of the lower extremities varying from grade 3 to grade 4. The cutaneous manifestations were heliotrope signs (6 cases), gottron's papules (2 cases), photosensitivity (2 cases) and calcinosis cutis (4 cases). Electromyography (EMG) was performed in 6 cases and revealed typical change of myopathic type. Elevated muscle enzymes were noted in all cases. Muscle biopsy was performed in 6 cases and was compatible with myositis. Oral prednisolone (1-2 mg/kg/day) was given in 6 cases and the muscle weakness improved. There was no mortality in this study. Four cases developed calcinosis cutis 1 to 3 years after muscle weakness and did not respond to any treatment. In conclusion, juvenile dermatomyositis is a disease which causes chronic disability in children. Early diagnosis and treatment can prevent morbidity and mortality. Calcification at the skin usually occurs after the onset of muscle weakness several months to years after diagnosis.