Dermatomyositis-polymyositis in children.

Sixteen cases of dermatomyositis-polymyositis in children (dermatomyositis 15; polymyositis 1) have been reviewed. Proximal muscle weakness with a characteristic skin rash was vital for diagnosis in the majority of children. The positive laboratory tests such as creatine phosphokinase (CPK), electromyography (EMG) and muscle biopsy were helpful but results were normal in some cases even in the acute phase of the illness. All but one had been treated initially with high dose corticosteroids followed by a low dose maintenance for a prolonged period. Two in addition had had cytotoxic agents. Thirteen of the sixteen were currently in remission. In the other three cases, one with polymyositis only, the disease remained active and the two with dermatomyositis died. Only three of the patients were incapacitated by residual fixed contractures and extruding calcinosis. On the whole the prognosis of dermatomyositis is good.