[Clinically amyopathic dermatomyositis : a rare entity associated with acute and severe interstitial lung disease].

Dermatomyositis is a rare disease of unknown etiology characterized by a severe inflammatory myopathy associated with a cutaneous syndrome. Dermatomyositis is associated with multisystemic disorders mostly represented by cardiac, pulmonary and articular involvements, which are particularly associated with a bad prognosis. We report a case of a 50-year-old patient suffering from dermatomyositis associated with an interstitial lung disease with a particularly fast and pejorative clinical evolution. The anti-Melanoma Differentiation-Associated gene 5 (anti-MDA5) antibodies are frequently associated with a severe and rapidly progressive lung disease without myositis named «amyopathic dermatomyositis». High blood levels of anti-MDA5 were found in our patient. Despite maximal immunosuppressive treatment and supportive care, he died 3 months after the diagnosis. Patients may present different antibodies that correspond to distinct clinical phenotypes of dermatomyositis. The anti-MDA5 is known to be a marker of clinically amyopathic dermatomyositis (CADM) associated with a rapidly progressive interstitial lung disease. Moreover, blood level of anti-MDA5 antibody predicts the response to treatment and survival in CADM.