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Dermatomyositis (DM) is a systemic disease with prominent skin and muscle features. Some patients have been described who appear to have disease localized to their skin for long periods of time and (in some instances) never seem to develop muscle disease. These patients have been labeled amyopathic dermatomyositis (ADM, previously known as dermatomyositis-sine-myositis). Classic DM has been linked to a potential for internal manifestations in
addition to the muscle disease, including, but not limited to, pulmonary disease and malignancy. The risk of these DM features in patients with ADM has been controversial; while some clinicians who specialize in this disease have felt that its incidence was rising, until recently there have been no epidemiologic studies that have detailed this increase.
As reviewed herein, Bendenwald et al1 used the Rochester Epidemiology Project (REP) to examine the incidence of DM and ADM in residents of Olmstead county, MN. They found that the incidence of ADM was roughly 20% of all DM cases, appeared to have risen over the past 30 years, and that both DM and ADM patients were at risk of having pulmonary disease or malignancy.
The possibility that patients with dermatomyositis may harbor a malignancy dates back to the early 1900s. By the mid-70s, when I began as a resident in dermatology, the relationship of skin findings to an increased risk of malignancy was considered controversial. My study comparing patients with dermatomyositis to those with polymyositis (PM) was perhaps one of the first to document this propensity (Arch Dermatol
1980);2 in a further report I suggested that the evaluation of patients should be more focused (J Am Acad Dermatol 1982).3 By the early 2000s, this controversy had been further resolved by findings from multiple population-based studies, primarily from Scandinavia (Siguregeirsson et al. 1992;4 Chow et al. 1995;5 Ario et al. 1995;6 Hill et al. 20017
). Further, several reports have attempted to determine the clinical and serologic factors that might be effective in predicting the chance of an associated malignancy. In addition, a study from Dartmouth University has shown demonstrated that the risk of cancer, even in a US population, is linked to skin associated disease (DM).10
Overall, the reported frequency of malignancy in dermatomyositis has varied from 6% to 60%, with most large population-based cohort studies revealing a frequency of about 20 to 25%. Fardet et al9 reported that 29 of their 121 patients with DM had a malignancy. As reviewed herein, Antichos et al10
found malignancy in 32 patients overall—24 with classic DM, 3 with ADM, 3 with PM, and 1 with overlapping features of another connective tissue disorder. Their analysis demonstrated not only that malignancy was significantly associated with DM, but that the incidence was much above that expected in the US population. In the recent population-based study from Mayo Clinic,1
malignancy was present in 28% of patients, strengthening the best previously existing data that 18-32% of dermatomyositis patients have or will develop a malignancy.
Malignancies may occur prior to the onset of myositis, concurrently with myositis, or after the onset of DM. In addition, the myositis may follow the course of the malignancy (a paraneoplastic course) or may follow its own course independent of the treatment of the malignancy. Studies demonstrating the benefits of cancer surgery on myositis, as well as those showing no relationship of the myositis to the malignancy have been
reported. In one retrospective study, independent factors associated with an underlying malignancy in dermatomyositis included age at diagnosis, rapid onset of skin and/or muscle symptoms, the presence of skin necrosis or periungal erythema, and a low baseline level of complement factor C4—whereas a low baseline lymphocyte count was a protective factor for associated malignancy.9
In addition, one recent study (Trallero-Araguás et al,11 reviewed herein) suggested that those with an anti-p155 antibody were more frequently linked to cancer associated disease, however there were patients with malignancy who did not have anti-p155 and there were patients in whom the antibody was positive but there was no associated malignancy.
A wide variety of malignancies have been reported in patients with DM. Gynecologic malignancy, in particular ovarian carcinoma, may be overrepresented in DM. Malignancy is more common in older patients (>50 years), but reports of young adults and children with DM and associated malignancy have appeared (Morris & Dare,12
reviewed herein), suggesting that age alone should not dissuade the physician from a careful evaluation. The site of malignancy can be predicted by the patient’s age (eg malignancy in a young man is more often testicular cancer, whereas, in an elderly male, colon or prostate cancer would be more common). In addition, the ethnicity of the patient is a factor in the sites of malignancies as noted in a recent national cohort study from
Taiwan.13
In the past, there was concern about whether the use of immunosuppressive therapies would predispose the patient to an excess cancer risk. This has not proven to be the case, with most cancers being reported within the first 3 years following diagnosis. There have been, however, cases of Epstein-Barr virus-associated lymphomas arising in patients with rheumatic diseases, including dermatomyositis, on methotrexate or other
immunosuppressive agents, which have resolved on discontinuation of immunosuppressive therapy without requiring additional therapy.14
The potential for lung disease in dermatomyositis was reported initially in Asian patients16, but the epidemiologic study from Mayo Clinic suggested that 17% of patients with ADM have pulmonary disease.1
In most cases patients have had interstitial fibrosis, although some patients with severe disease, including bronchiolitis obliterans-organized pneumonia (BOOP), have been reported as well. Treatment of pulmonary involvement has traditionally included high dose corticosteroids and cyclophosphamide. However, in a recent study in this issue, Morganroth et al15
reported control and resolution of pulmonary disease in patients treated with mycophenolate mofetil.
Although this disease is relatively rare, these recently published papers provide practical utility in evaluating and managing patients with dermatomyositis.
Commentary References
| 1. |
Bendewald MJ, Wetter DA, Li X, Davis MD. Incidence of dermatomyositis and clinically amyopathic dermatomyositis: a population-based study in Olmsted County, Minnesota. Arch Dermatol. 2010 Jan;146(1):26-30. |
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| 2. |
Callen JP, Hyla JF, Bole GG Jr, Kay DR. The relationship of dermatomyositis and polymyositis to internal malignancy. Arch Dermatol. 1980 Mar;116(3):295-298. |
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| 3. |
Callen JP. The value of malignancy evaluation in patients with dermatomyositis. J Am Acad Dermatol. 1982 Feb;6(2):253-259. |
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| 4. |
Sigurgeirsson B, Lindelöf B, Edhag O, Allander E. Risk of cancer in patients with dermatomyositis or polymyositis. A population-based study. N Engl J Med. 1992 Feb 6;326(6):363-367. |
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| 5. |
Chow WH, Gridley G, Mellemkjaer L, McLaughlin JK, Olsen JH, Fraumeni JF Jr. Cancer risk following polymyositis and dermatomyositis: a nationwide cohort study in Denmark. Cancer Causes Control. 1995 Jan;6(1):9-13. |
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| 6. |
Airio A, Pukkala E, Isomäki H. Elevated cancer incidence in patients with dermatomyositis: a population based study. J Rheumatol. 1995 Jul;22(7):1300-1303. |
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| 7. |
Hill CL, Zhang Y, Sigurgeirsson B, et al. Frequency of specific cancer types in dermatomyositis and polymyositis: a population-based study. Lancet. 2001 Jan 13;357(9250):96-100. |
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| 9. |
Fardet L, Rybojad M, Gain M, et al. Incidence, risk factors, and severity of herpesvirus infections in a cohort of 121 patients with primary dermatomyositis and dermatomyositis associated with a malignant neoplasm. Arch Dermatol. 2009 Aug;145(8):889-893. |
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| 10. |
Antiochos BB, Brown LA, Li Z, Tosteson TD, Wortmann RL, Rigby WF. Malignancy is associated with dermatomyositis but not polymyositis in Northern New England, USA. J Rheumatol. 2009 Dec;36(12):2704-2710. |
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| 11. |
Trallero-Araguás E, Labrador-Horrillo M, Selva-O'Callaghan A, et al. Cancer-associated myositis and anti-p155 autoantibody in a series of 85 patients with idiopathic inflammatory myopathy. Medicine (Baltimore). 2010 Jan;89(1):47-52. |
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| 12. |
Morris P, Dare J. Juvenile dermatomyositis as a paraneoplastic phenomenon: an update. J Pediatr Hematol Oncol. 2010;32:189–191. |
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| 13. |
Chen YJ, Wu CY, Huang YL, Wang CB, Shen JL, Chang YT. Cancer risks of dermatomyositis and polymyositis: a nationwide cohort study in Taiwan. Arthritis Res Ther. 2010 Apr 16;12(2):R70. |
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| 14. |
Waldman MA, Callen JP. Self-resolution of Epstein-Barr virus-associated B-cell lymphoma in a patient with dermatomyositis following withdrawal of mycophenolate mofetil and methotrexate. J Am Acad Dermatol. 2004 Aug;51(2 Suppl):S124-30. |
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| 15. |
Morganroth PA, Krieder ME, Werth VP. Mycophenolate mofetil for interstitial lung disease in dermatomyositis. Arthritis Care Res (Hoboken). 2010 Apr 9. |
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| 16. |
Takizawa H, Shiga J, Moroi Y, Miyachi S, Nishiwaki M, Miyamoto T. Interstitial lung disease in dermatomyositis: clinicopathological study. J Rheumatol. 1987 Feb;14(1):102-107. |
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