musculoskeletal and connective tissue disorders
Autoimmune Myositis
Etiology of Autoimmune Myositis
The cause of autoimmune myositis seems to be an autoimmune reaction to muscle tissue in genetically susceptible people. Familial clustering occurs, and human leukocyte antigen (HLA) subtypes are associated with myositis. For example, the alleles of the 8.1 ancestral haplotype (HLA-DRB1*03-DQA1*05-DQB1*02) increase risk of polymyositis, dermatomyositis, and Overview of Interstitial Lung Disease . Possible inciting events include viral myositis and underlying cancer. The association of cancer with dermatomyositis (less so with polymyositis) suggests that a tumor may incite myositis as the result of an autoimmune reaction against a common antigen in muscle and tumor. 