Polymyositis-dermatomyositis

Polymyositis-dermatomyositis (PM-DM) is a group of subacute or chronic onset of acquired inflammatory myopathy, whose main pathological characteristics are muscle fiber necrosis, regeneration, and intramuscular inflammatory Cell infiltration. The etiology of PM-DM is unknown, so far it is still a diagnosis of exclusion. Any inflammatory myopathy that does not find a clear infectious factor (such as virus, bacteria, parasites, etc.) belongs to this disease category, so it is also called idiopathic Idiopathic inflammatory myopathy. Since this group of diseases responds well to corticosteroid therapy, it is speculated that the pathogenesis may be related to autoimmune abnormalities. The main clinical manifestations of polymyositis (PM) are diffuse inflammatory myopathy, which is characterized by weakness of the proximal limbs, neck and pharynx muscle groups with pain. Those with a typical rash are called dermatomyositis (DM). About one-third of patients can be associated with other connective tissue diseases, and 1/10 patients are associated with tumors. Polymyositis-Dermatomyositis Renal damage is seen in a small number of patients.