Cutaneous immunofluorescence in dermatomyositis

Seven patients with dermatomyositis who displayed severe skin and muscle disease, and in whom coexistent systemic lupus erythematosus (LE) was excluded, were evaluated by direct immunofluorescent biopsies of skin lesions. Specimens from six showed deposits of immunoglobulins and complement in small to moderate amounts at the dermal-epidermal junction zone. These deposits were usually in the form of focal granular accumulations which lacked continuity and were not well developed as are those seen in LE, or fluorescent subepidermal hyaline bodies. One patient, however, had a more well developed band of immunoglobulins at the dermal-epidermal junction. All normal skin specimens in these patients were negative by immunofluorescence. These findings were helpful in clarifying differences in cutaneous immunofluorescence between dermatomyositis and LE, indicating that dermatomyositis specimens can usually be differentiated from those of LE patients, but demonstrating the possibility that confusion might rarely occur in interpreting a lesional immunofluorescent biopsy in dermatomyositis.