Paraneoplastic myopathy

It has been recognized for some time now, that compared with the normal population, patients with idiopathic inflammatory myopathies (IIM) live with an increased risk of developing malignancy. In the majority of these patients, cancer-associated myositis appears to have some paraneoplastic features. The aim of the present review is to describe new data that explain the connection between myositis and malignant diseases, as well as to highlight its value in the current management of these patients.

Antigen expressions and patterns shared by regenerating muscle and cancers raise questions about whether myositis cases without clinically observable cancer may represent a fully successful antitumor immune response with bystander damage to regenerating muscle. The discovery of anti-155/140 autoantibody may aid in the better diagnosis of adult IIM patients with a higher risk of malignancy. It also may help the better understanding of paraneoplastic myositis.

Cancer-associated myositis differs from primary myositis in many aspects. Prognosis and life-expectancy are determined by the underlying malignancy. Therefore, patient-specific examinations for detection of an underlying cancer are important in the management of patients. Recent clinical findings and new possibilities in immunoserological testing may result in the elaboration of an evidence-based recommendation for cancer screening programs in patients with IIM in the future.