Dermatomyositis

Abstract

ABSTRACT: Dermatomyositis (DM) is an acquired, inflammatory muscle disorder of unknown etiology characterized by symmetrical proximal muscle weakness, inflammatory myositis on biopsy, elevation of serum muscle enzymes, abnormal electromyogram, and a typical rash, with or without internal organ involvement. Untreated muscle disease can produce severe and long-term disabilities, and the cutaneous lesions can cause considerable discomfort from intractable pruritus. A prompt and usually aggressive approach to therapy is indicated, with each patient's management depending on the severity of the skin and muscle disease and the presence or absence of multisystem involvement. The mainstay of therapy for DM is the use of systemic corticosteroids. In those patients that do not respond to steroids or develop significant steroid-related side effects, immunosuppressive agents (methotrexate, azathioprine, cyclophosphamide, and more recently cyclosporine), or intravenous immunoglobulin (IVIG) are used. General measures include bed rest, passive range-of-motion exercises, and active physical therapy. Overall the use of corticosteroids with or without immunosuppressive agents has significantly reduced mortality and increased functional recovery. Corticosteroids may not control the rash. In these cases aminoquinolone antimalarials have been advocated, though partial improvement is more common than complete control. Emollients and photoprotection are essential. In recalcitrant cases of cutaneous DM, low-dose methotrexate and IVIG have been used with success. Finally, with the recognition of distinct subsets limited to the skin (e.g., amyopathic DM), the dermatologist is confronted with the decision for appropriate therapeutic modalities tailored to the individual patient's needs.