[Mediastinal cancer presenting as dermatomyositis--a case report].

We present a case of a 47-year-old man with mediastinal cancer manifesting as a rash, myaLgia and muscle weakness, in addition to the typical laboratory test results and histological changes compatible with dermatomyositis. The skin and muscLe findings followed the relapse of cancer which responded well to a combination of chemo and radiation therapy. Disease prevaLence in Rambam MedicaL Center during the past decade is also described. Dermatmyositis is a myositis with cutaneous manifestations. In a significant percent of the cases it can occur as a paraneoplastic syndrome. It was described as coetisting with various cancers, mostly adenocarcinomas. The majority of the cases occur in males above the age of 45 years. Malignancy can occur simultaneously with dermatomyositis or up to 3 years thereafter. Ovarian cancer is an exception, for it can be diagnosed up to six years after dermatomyositis. Therefore, it is advised to perform cancer screening in adult patients with dermatomyositis. Screening shouLd incLude extensive laboratory and imaging work-up. However, the mechanisms underlying paraneoplastic dermatomyositis are not fully understood. A possible antigenic similarity between cancer cell popuLations and regenerating myoblasts is suggested; this can result in an autoimmune autoantibody-mediated response in genetically predisposed patients. Numerous laboratory and clinical characteristics are associated with a high risk of malignancy. An update on paraneoplastic dermatomyositis is provided.