Relationship of cancer to inflammatory muscle diseases. Dermatomyositis, polymyositis, and inclusion body myositis.

Dermatomyositis (DM) is probably associated with a greater frequency of malignancy than expected in the general population. For polymyositis (PM), there does not appear to be greatly increased risks. Ovarian cancer may be over-represented in women with DM. A paraneoplastic course occurs in some patients with DM, but is unusual. Even young patients with DM should be evaluated. The malignancy evaluation should be directed by symptoms, findings on physical examination or laboratory testing, or be age-appropriate.