Six patients initially had the characteristic skin eruption of dermatomyositis but no other evidence of the disease. They all later developed dermatomyositis. The clinical, laboratory, and pathological data suggest that whereas polymyositis may occur without skin involvement, the cutaneous features of dermatomyositis may be seen in the absence of detectable muscle disease. This variant of dermatomyositis occurs in children and adults but has not been found to be associated with internal malignant disease. The persistence of skin lesions despite systemic corticosteroid therapy is a poor prognostic sign. There were two patients with pulmonary fibrosis and dermatomyositis in this group. The presence of pulmonary fibrosis can contribute to a delay in diagnosis of dermatomyositis. Patients with pulmonary fibrosis had a poorer prognosis, despite moderate dosages of corticosteroids.
Krain LS. Dermatomyositis in Six Patients Without Initial Muscle Involvement. Arch Dermatol. 1975;111(2):241-245. doi:10.1001/archderm.1975.01630140099013