Dermatomyositis

Lupus erythematosus, acute rheumatic carditis, systemic dermatomyositis DERMATOLOGIC DISEASES... 

Polymyositis and Dermatomyositis Syndromes Polymyositis and Dermatomyositis Associated with Malignancy Inclusion Body Myositis (IBM)... 

Figure 17. Inflammatory cell infiltrate in a muscle biopsy from a patient with dermatomyositis note compact nature of infiltrate and perivascular location.

The incidence of these syndromes seems to vary according to geographical area and ethnic background but is about 0.2-0.3 per 100,000.population (mean annual incidence rate). However incidence rates calculated for adult populations are up to three times higher. The fifth and sixth decades show peak incidence rates and there is also clear biomodality across the full age spectrum due to the existence of a juvenile form of dermatomyositis (JDM) which is pathogenetically distinct. Polymyositis, uncomplicated by skin changes, can also occur as a juvenile condition. 

Juvenile dermatomyositis (JDM) is perhaps the most uniform, in terms of clinical and histopathological features, of the whole PM/DM disease complex. Presentation may be before 5 years of age with peak incidence between 8 and 12 years. The disease may remit and recur until well into young adult life. The skin lesions include a facial rash in butterfly distribution across nose and cheeks. Erythematous skin changes are seen over extensor surfaces of joints, especially knees, knuckles and elbows. Muscle involvement is generally evident some time later and takes the form of weakness and stiffness, particularly affecting shoulder and pelvic musculature. Proximal muscles are often worse affected than distal muscles and extensors worse than flexors. In the absence of prompt and effective treatment contractures may occur at elbows, ankles, knees, and hips. Subcutaneous calcification and skin ulceration may be found calcification of deeper-lying connective tissue may be apparent on X-ray. 

Figure 18. (a) Immunocytochemical labeling of B-lymphocytes in muscle from a patient with juvenile dermatomyositis. (b) Immunocytochemical labeling of T8 lymphocytes showing that the infiltrate contains very few cells of this type (serial section). 

Figure 19. Juvenile dermatomyositis, showing atrophy of perifascicular fibers and strong reactivity for MHC-I antigen in these fibers.

The histopathological features of PM may be radically different from those of JDM and ADM. There is little, if any, evidence of involvement of the micro vasculature and the muscle necrosis which occurs appears to be the direct result of targeting of individual muscle fibers. In the dermatomyositis syndromes, antibody-dependent humoral mechanisms are predominant and B-lymphocytes are seen to be the most abundant cell type in almost all JDM cases and a substantial proportion of ADM cases. In contrast, most muscle biopsies from PM patients show evidence of inflammation in which TS (cytotoxic) lymphocytes predominate (Figure 20). Moreover, the distribution of inflammatory cell infiltrates tends to be different. Instead of the mainly perifascicular location of lymphocytes in JDM/ADM, there... 

Fall N, Bove KE, Stringer K, et al. Association between lack of angiogenic response in muscle tissue and high expression of angiostatic ELR-negative CXC chemokines in patients with juvenile dermatomyositis possible link to vasculopa-thy. Arthritis Rheum 2005 52(10) 3175-3180. 

Polymyositis/dermatomyositis 5 67% Translational factors, others Ultraviolet radiation/vitamin D... 

One of the primary reasons ultraviolet radiation is of interest in the context of autoimmune diseases is because of induction of photosensitive cutaneous lesions (cutaneous lupus erythematosus)82 and dermatomyositis.83 A recent global evaluation of the frequency of dermatomyositis and associated autoantibodies in referral centers around the world showed a positive correlation with the intensity of ultraviolet irradiation at those locations.84... 

Positive association with frequency of dermatomyositis in one study inverse association with risk of diabetes and MS. Inhibition of disease in rodent models of multiple sclerosis, type 1 diabetes and inflammatory bowel disease but acceleration... 

Miller, F.W., Inflammatory Myopathies Polymyositis, Dermatomyositis, and Related Conditions, in Arthritis and Allied Conditions —A Textbook of Rheumatology (15th Edition), Koopman, W. and Moreland, L., Eds., 2004 chap. 75 (volume 2), ppl593-1620. 

Seelig, H.P., Moosbrugger, I., Ehrfeld, H., Fink, T., Renz, M., and Genth, E. (1995) The major dermatomyositis-specific Mi-2 autoantigen is a presumed helicase involved in transcriptional activation. Arthritis Rheum. 38, 1389-1399. 

Zhang, Y., LeRoy, G., Seelig, H.P., Lane, W.S., and Reinberg, D. (1998) The dermatomyositis-specific autoantigen Mi-2 is a component of a complex containing histone deacetylase and nucleosome remodeling activities. Cell 95, 279-289. 

Wang, H.-B. and Zhang, Y. (2001) Mi2, an auto-antigen for dermatomyositis, is an ATP-dependent nucleosome remodeling factor. Nucleic Acids Res. 29, 2517-2521. 

Collagen diseases For exacerbation of maintenance therapy in selected cases of systemic lupus erythematosus, acute rheumatic carditis, or systemic dermatomyositis (polymyositis). 

Hepatotoxicity Penicillamine has been associated with a mild elevation of hepatic enzymes that usually returns to normal even with continuation of the drug. Autoimmune syndromes Autoimmune syndromes that may be caused by penicillamine include polymyositis, diffuse alveolitis and dermatomyositis, Goodpasture s syndrome, myasthenic syndrome, pemphigus, and obliterative bronchiolitis. 

The autoimmune rheumatic diseases consists of Rheumatoid Arthritis (RA), Spondylarthritis (SpA), Systemic Lupus Erythematosus (SLE), Polymyositis, Dermatomyositis, Polymyalgia Rheumatica, Acute Temporal Arteritis, Giant Cell Arteritis, Behcet s Disease, Sjorgren s Syndrome, Felty s Syndrome and Mixed Connective Tissue Disease (MCTD). Spondylarthritis (SpA) can be subdivided in Reactive Arthritis (ReA), Ankylosing Spondylitis (AS), Psoriatic Arthritis (PsA), Arthritis associated with the inflammatory bowel diseases are Crohn s disease and Ulcerative Colitis (IBD), Undifferentiated SpA (UspA) and Sacro-ilitis, Juvenile SpA and Acute Anterior Uveitis (AAU). 

Cyclosporine is approved for use in rheumatoid arthritis and retards the appearance of new bony erosions. Its usual dosage is 3-5 mg/kg/d divided into two doses. Anecdotal reports suggest that it may be useful in systemic lupus erythematosus, polymyositis and dermatomyositis, Wegener s granulomatosis, and juvenile chronic arthritis. 

Bachelez H, Schremmer B, Cadranel J, Mouly F, Sarfati C, Agbalika F, Schlemmer B, Mayaud CM, Dubertret L. Fulminant Pneumocystis carinii pneumonia in 4 patients with dermatomyositis. Arch Intern Med 1997 157(13) 1501-3. 

A few cases of dermatomyositis and polymyositis due to cholesterol-lowering drugs have previously been reported. Symptoms in four men and one woman, median age 68 years, were compatible with a diagnosis of... 

Collagen disorders Immunosuppression Acute rheumatic carditis, dermatomyositis, systemic lupus erythematosus... 

Clinical Use. Azathioprine (Imuran) is a cytotoxic agent that is structurally and functionally similar to certain anticancer drugs, such as mercaptopurine.22,30 Azathioprine is primarily used to prevent the rejection of transplanted organs, especially in patients with kidney transplants. Azathioprine may also be used to suppress immune responses in a wide range of other conditions, such as systemic lupus erythematosus, dermatomyositis, inflammatory myopathy, hepatic disease, myasthenia gravis, and ulcerative colitis. As presented in Chapter 16, azathioprine is also used as an antiarthritic disease-modifying agent. 

Therapists also deal with the rehabilitation of musculoskeletal disorders that are caused by an autoimmune response. Many of these diseases attack connective tissues, and autoimmune diseases such as rheumatoid arthritis, dermatomyositis, and systemic lupus erythematosus are often the primary reason that patients undergo rehabilitation. Patients with a compromised immune system may develop musculoskeletal problems related to their immunodeficient state. Hence, immunomodulating drugs are frequently used in many patients receiving physical therapy and occupational therapy. 

Although the most common methotrexate dosing regimens for the treatment of rheumatoid arthritis are 15 or 17.5 mg weekly, there is an increased effect up to 30 or 35 mg weekly. The drug decreases the rate of appearance of new erosions. Evidence supports its use in juvenile chronic arthritis, and it has been used in psoriasis, psoriatic arthritis, polymyositis, dermatomyositis, Wegener s granulomatosis, giant cell arteritis, subacute lupus erythematosus, and vasculitis. 

The term classical PNS is reserved for the PNS in which the association with cancer is common and includes encephalomyelitis, limbic encephalitis, paraneoplastic cerebellar degeneration, and paraneoplastic opsoclonus myoclonus (OM), as well as sensory neuronopathy (SN), chronic gastrointestinal pseudo-obstruction, Lambert Eaton myasthenic syndrome (LEMS), and dermatomyositis [14]. This chapter does not include dermatomyositis. 

---