Polymyositis and Dermatomyositis

POLYMYOSITIS is an inflammatory myopathy of unknown cause to which the term dermatomyositis is applied in the presence of the characteristic skin rash. These disorders share common features with the connective-tissue diseases and are usually classified together. It is said that there is an increased association with neoplasia.The Problem of DiagnosisThere are at present no generally accepted criteria for the diagnosis of polymyositis-dermatomyositis akin to the Jones criteria for rheumatic fever or to the American Rheumatism Association criteria for rheumatoid arthritis. Consequently, the basis for the diagnosis has varied widely in retrospective studies, which, . . .