Cancer-associated myositis: an elusive entity

Inflammatory myopathies are characterized by the skeletal muscle inflammation leading to symptoms of myopathy along with varying involvement of other organs such as lung, skin and joints. The strong association between inflammatory myopathies and malignancy has been well recognized. Recently, ‘cancer-associated myositis (CAM)’, has been proposed to be a paraneoplastic syndrome due to the anti-tumor immunity secondary to similar tumor and regenerating muscle antigens. As the prognosis of myositis depends on the prognosis and treatment of the underlying malignancy, physicians must determine the degree of testing necessary to detect cancer both at myositis onset and thereafter. However, there are no clear guidelines regarding the best approach. Emerging medical evidence shows that identification of certain risk factors and serology patterns can be utilized to predict cancer risk in patients with myositis.