Myositis and malignancy.

Dermatomyositis appears to be associated with a greater frequency of malignancy than expected in the general population. For polymyositis, there does not appear to be a greatly increased risk of malignancy. Ovarian cancer may be overrepresented in women with dermatomyositis and difficult to detect. A paraneoplastic course, in which the activity of the myositis parallels that of the malignancy, occurs in some patients but is unusual. Although the frequency of malignancy rises with increasing age, young patients may harbor malignancy. The search for malignancy should be directed by symptoms, findings on physical examination, or laboratory testing, and it should be age appropriate.