The cause is unknown, but it may result from an initial viral infection or cancer, either of which could raise an autoimmune response. Between 7 and 30% of<unk>  arise from cancer, probably as an autoimmune response. The most commonly associated cancers are ovarian cancer, breast cancer, and lung cancer. 18 to 25% of people with amyopathic<unk>  also have cancer. Malignancy in association with<unk>  is more prevalent after age 60. Some cases are inherited, and HLA subtypes HLA-DR3, HLA-DR52, and HLA-DR6 seem to create a disposition to autoimmune<unk> .
Dermatomyositis
Scleroderma
Inclusion body myositis
Polymyositis
Scleromyositis
Dermatopolymyositis
Trichinosis
Juvenile dermatomyositis