VIENNA – Adult patients who are diagnosed with dermatomyositis should have a thorough work-up for malignancy because they are at heightened risk for various cancers, Dr. Ralph M. Trueb said at the 16th Congress of the European Academy of Dermatology and Venereology.
About 15%-30% of patients with this inflammatory autoimmune disorder will develop cancer, with the risk being most prominent early in the course of disease. Most reported malignancies are carcinomas rather than sarcomas or lymphomas, said Dr. Trueb of the University Hospital of Zurich.
The work-up should include a chest radiograph, Pap smear, and breast and rectal examinations, and should be repeated at regular intervals, he said.
Patients are also at risk for potentially life-threatening organ involvement. The lung is involved in 40% of these patients, with the development of aspiration pneumonia, interstitial fibrosis, and respiratory insufficiency. The joints, gastrointestinal tract, and cardiovascular system also can be affected. More than one-fourth of patients have arthritis, and electrocardiogram abnormalities are present in half of patients.
The condition also may be limited to the skin or muscles. The skin lesions typical of dermatomyositis can be classified as pathognomonic, characteristic, or compatible, Dr. Trueb said.
Pathognomonic findings include Gottron's papules, which are slightly elevated violaceous papules located over the joints of the hands, as well as over the ankles, knees, and elbows, and Gottron's sign, which refers to the erythematous plaques that spare the interphalangeal spaces.
“It's important to note that, while the skin lesions in dermatomyositis can resemble those seen in lupus, they are located over the joints in dermatomyositis and primarily between the joints in lupus,” he said.
Characteristic skin findings include a heliotrope periorbital rash with or without associated periorbital edema; the “shawl sign,” which is a symmetrical macular violaceous erythema at the nape of the neck and around the shoulders; and scalp involvement, including alopecia.
Compatible findings include poikiloderma, especially in long-standing disease, and calcinosis.
Muscle manifestations include progressive weakness, electromyographic changes, and elevations of muscle enzymes such as creatine kinase. “Patients lose the ability to raise their arms for hair grooming or shaving,” Dr. Trueb said. They may subsequently become unable to climb stairs, to rise from a sitting position, or to walk unaided. Patients with severe muscle involvement have a poor prognosis, he said.
First-line treatment remains high-dose oral corticosteroids, but this is evolving, with increasing reports of the use of intravenous immunoglobulin (IVIg) and the biologic drugs, he said.
In one series, eight patients with dermatomyositis or poly-myositis who had not responded to corticosteroids, IVIg, and immunosuppressants received a tumor necrosis factor inhibitor. Six of the eight showed improvements in muscle strength and fatigue and marked reductions in creatine kinase (Ann. Rheum. Dis. 2006;65:1233-6).
The B-cell-depleting monoclonal antibody rituximab also has now been used in a small number of patients with refractory disease. In an open-label pilot study that included six patients who each received four infusions of rituximab, muscle strength improved 36%-113% over baseline, beginning as early as 12 weeks after the initial infusion (Arthritis Rheum. 2005;52:601-7).
In a more recent report describing three patients whose cutaneous lesions responded well to rituximab, researchers from Australia suggested a possible mechanism by which this drug might act in dermatomyositis. They noted that B lymphocytes are not present in the skin lesions in this disorder, and that T cells predominate in areas of skin changes. They suggested that the drug may affect T cells as well as B cells, possibly through downstream effects on costimulatory molecules that inhibit activation and development of T helper type 1 cell dominance (J. Am. Acad. Dermatol. 2007;56:148-53).