Dermatomyositis

Clinical features

Dermatomyositis is an idiopathic inflammatory myopathy with characteristic cutaneous manifestations. These include a heliotrope rash involving the periorbital skin, erythematous scaly plaques on dorsal hands with periungual telangiectasia and joint eruptions (Gottrons’s papules) and a photosensitive poikilodermatous eruption. The myopathy primarily affects the proximal muscles, is generally symmetrical, and is slowly progressive during a period of weeks to months. The diagnosis is made by the combination of typical skin changes, muscle weakness, elevated serum CK and typical changes in the neurophysiological studies and muscle biopsy.

Dermatomyositis in adults over 40 years of age is associated with malignant disease, particularly ovarian, lung, pancreatic, stomach, and colorectal cancers, and non-Hodgkin lymphoma. In most patients the tumour is diagnosed by the time the myopathic symptoms develop. In patients with dermatomyositis, the risk of cancer is higher in women than men. Except for older age, there are no clinical or laboratory markers for the presence of an underlying tumour, and close clinical follow up is indicated for these patients.

Associated antibodies

Antinuclear antibody testing is commonly positive. Many myositis-associated antibodies have been recognised in dermatomyositis, but none are linked to tumours.

Treatment

The treatment of patients with cancer and dermatomyositis should be directed primarily to the tumour. Immunosuppressive treatment is also very important, and includes corticosteroids, azathioprin and ivIgG.

Selected references:

1. Callen, JP. Dermatomyositis. Lancet 2000; 355: 53-57.
2. Hill CL, Zhang Y, Sigurgeirsson B, et al. Frequency of specific cancer types in
dermatomyositis and polymyositis: a population-based study. Lancet 2001; 357: 96-100.
3. Dalakas MC. Polymyositis, dermatomyositis and inclusion-body myositis. N Eng J Med 1991;325:1487-1498
4. Barnes B. Dermatomyositis and malignancy. Ann Int Med 1976;84:68-76
5. Sigurgeirsson B, Lindelöf B, Edhag O, Allander E. Risk of cancer in patients with dermatomyositis or polymyositis. N Engl J Med 1992;326:363-367