A Study on Dermatomyositis and the Relation to Malignancy

The idiopathic inflammatory myopathies (IIM) are a group of heterogeneous systemic diseases which include as main subtypes: polymyositis (PM), dermatomyositis (DM) and inclusion body myositis (IBM). The key feature of IIMs is the muscle weakness, accompanied by a characteristic skin rash in DM patients. The overall risk for malignancy in IIM is higher compared to the age-and sex-matched general population. Most epidemiologic studies have included only PM and DM patients and reported consistently higher rates of malignancy in DM. Most common types of cancer in DM are adenocarcinoma of the lung, ovary or gastrointestinal tract, melanoma and non-Hodgkins lymphoma. The highest risk for malignancy is seen in the first year after DM diagnosis. Multiple disease features have been linked to the development of cancer in DM. These include: older age, male sex, skin necrosis, Gottron sign, heliotrope rash, dysphagia, low complement C4, lymphocytosis, poor response to corticosteroids and rapid disease progression. Our study included 23 patients with DM, divided into two groups based on the association of malignancy, in order to compare clinical and demographic features, laboratory markers and analyze characteristic of cancer development.