Cutaneous changes of dermatomyositis in patients with normal muscle enzymes: dermatomyositis sine myositis?

Overview

BACKGROUND: Dermatomyositis sine myositis may have various connotations. Controversy exists as to nomenclature, degree of evaluation required, therapy, and course (e.g., does true dermatomyositis of the skin only exist?). OBJECTIVE: The purpose of this study was to assess prospectively patients with the clinicopathologic features of dermatomyositis and normal muscle enzyme serum levels to determine their course in terms of the onset of muscle disease. METHODS: Thirteen patients were studied by complete history and clinical examination, laboratory studies, electromyography, and skin and muscle biopsy. They were observed for 1 to 6 years. RESULTS: Patients were classifiable into three groups: (1) cutaneous changes only, (2) cutaneous changes only at baseline with subsequent development of myositis, and (3) cutaneous changes with normal muscle enzyme serum levels at baseline but with myositis demonstrated by electromyography and/or muscle biopsy specimens. CONCLUSION: Significantly different prognostic and therapeutic implications are present in patients with dermatomyositis with normal muscle enzyme serum levels depending on the results of electromyography, muscle biopsy, and clinical observation.