Dermatomyositis and malignancy.

During the past 12 years, many studies applying strict diagnostic criteria have been published that have attempted to settle the controversy about the reality of the association between dermatomyositis and malignancy. Although retrospective, recent studies have shown an increased incidence of malignancy among patients with dermatomyositis when compared with controls without myositis. In contrast, an increased frequency of malignancy in dermatomyositis as compared to polymyositis still has to be demonstrated. In most cases, malignant disease precedes or occurs concurrently with dermatomyositis and is discovered on the basis of clinical signs, symptoms, and routine screening laboratory tests. The types of neoplasms found in association with dermatomyositis parallel those observed in the general population. A possible link between dermatomyositis and an underlying malignancy remains largely hypothetical at a biologic level, although cellular immunity abnormalities may provide a direction for future investigations. Prospective epidemiologic studies using the case-control methods and cohort analysis remain necessary 1) to rigorously demonstrate the reality and to study the nature of the association between dermatomyositis and malignancy, and 2) to clarify the optimal screening strategies for malignant neoplasms in patients with dermatomyositis.