In the late 19th century,<unk>  were described by different scientists.<unk>  are subtypes of idiopathic inflammatory myopathy. Patients develop proximal muscle weakness manifested as difficulty to raise their arms above the shoulders or from chair, or climbing stairs and progress to distal muscle weakness. Patients with<unk>  suffer from skin lesions in which Gottron's papules and the heliotrope eruption considered as pathognomonic features. The exact pathogenesis of<unk>  is not fully understood. However, it is understood that<unk>  are the result of autoimmune attack but triggering factors are not well-known.<unk>  is caused by inflammation and degeneration of the muscles.<unk>  is caused by skin inflammation. In<unk> , activation and deposition of complements may lead to lysis of endomysial capillaries and muscle ischemia. Genes including HLA DRB1*0301 and HLA DQA1*0501 alleles, and tumour necrosis factor 308A might be associated with development of<unk> , especially in familial cases. Different conditions associated with<unk>  include respiratory and cardiac diseases, other connective tissue diseases, and malignancies. The incidence of<unk>  is approximately 1-5 per 100,000 individuals worldwide. The prevalence of<unk>  is approximately 5-22 per 100,000 individuals worldwide. The 5-year survival rate for<unk>  is 75% and for<unk>  is 63%. The median survival for<unk>  is 11.0 years and that for<unk>  is 12.3 years. Muscle biopsy is the gold standard test for the diagnosis of<unk> . Prognosis of<unk>  varies depends on different studies. Prognosis is generally poor, and the overall mortality rate of patients with<unk>  is approximately 22%. Most common cause of death in patients with<unk>  include cardiac and pulmonary complications, infections, and cancers. Common risk factors in the development of<unk>  include environmental factors such as infection, malignancy, and drug toxicities from statins or immune checkpoint inhibitors. Effective measures for prevention of complications include regular follow ups, malignancy screening, pulmonary protection, lifestyle modification, and prevention of medication-induced complications.
Polymyositis and dermatomyositis
Diabetes mellitus and COVID-19
Polymyalgia rheumatica epidemiology and demographics
Juvenile dermatomyositis
Dermatomyositis other diagnostic studies
Statin induced myopathy epidemiology and demographics
Behçet's disease epidemiology and demographics
Arthritis-dermatitis syndrome