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Current Concepts in the Idiopathic Inflammatory Myopathies: Polymyositis, Dermatomyositis, and Related Disorders
- Paul H. Plotz, MD;
- Marinos Dalakas, MD;
- Richard L. Leff, MD;
- Lori A. Love, MD, PhD;
- Frederick W. Miller, MD, PhD; and
- Mary E. Cronin, MD
Abstract
Idiopathic inflammatory myopathy, a category encompassing polymyositis, dermatomyositis, and a number of other disorders, is very uncommon, but has been the focus of intense study in the Arthritis and Rheumatism Branch of the National Institute of Arthritis and Musculoskeletal and Skin Diseases for the past several years. We describe the clinical picture, stressing the need for biopsy to ensure correct diagnosis. It is especially important to recognize the treatment-resistant variant, inclusion body myositis. The extraskeletal manifestations, particularly the cardiopulmonary, oropharyngeal, gastrointestinal, and endocrine involvement, are described. The cardiopulmonary involvement, especially interstitial lung disease, arrhythmias, and cardiac failure, may dominate the clinical picture. The known causes are varied, and include drugs, toxins, and some infectious agents, however, in most cases a cause cannot yet be identified. Circumstantial evidence suggests that picornaviruses may initiate some cases in humans, and a very similar disease in mice caused by a picornavirus is actively under study. Studies of autoantibodies and cellular immune function support a central role for disordered immunity in the pathogenesis. The myositis-specific autoantibodies, especially those directed at certain enzymes important in protein synthesis (the amino-acyl-transfer RNA synthetases), are found in a clinically distinct subset of patients. Although most patients respond initially to corticosteroids, cytotoxic drugs are sometimes added when steroid toxicity or refractoriness develops. We describe several newer therapies under study for such cases and outline future directions in research.
Article and Author Information
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An edited summary of a Combined Clinical Staff Conference held 6 April 1988 at the Amphitheater, Building 10, Bethesda, Maryland, sponsored by the National Institutes of Health, U.S. Department of Health and Human Services.
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Authors who wish to cite a section of the conference and specifically indicate its author may use this example for the form of reference:
Dalakas M. Biopsy findings in skeletal muscle, pp 146-147. In: Plotz PH, moderator. Current concepts in the idiopathic inflammatory myopathies: polymyositis, dermatomyositis, and related disorders. Ann Intern Med. 1989;111:143-157.
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Requests for Reprints: Paul H. Plotz, MD, Building 10, Room 9N228, National Institutes of Health, Bethesda, MD 20892.
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Current Author Addresses: Drs. Plotz, Leff, Love, and Miller: Building 10, Room 9N228, National Institutes of Health, Bethesda, MD 20892.
Dr. Dalakas: Building 10, Room 4N248, National Institutes of Health, Bethesda, MD 20892.
Dr. Cronin: Evanston Hospital, 2650 Ridge Avenue, Evanston, IL 60201.
