UV and Idiopathic Inflammatory Myopathies: Evidence for a Connection with Dermatomyositis but Not Polymyositis

Ultraviolet radiation has a number of deleterious effects on human health. It causes photoaging of the skin and skin cancer and also has a provocative effect on such autoimmune diseases as lupus and dermatomyositis. In dermatomyositis, UV radiation can cause photosensitive skin rash and may exacerbate the underlying disease process itself. To investigate the relation between UV exposure and dermatomyositis, researchers examined the records of 380 patients (78% women) with idiopathic inflammatory myopathies (dermatomyositis 178, and polymyositis, 202) for correlation between the clinical and immunologic expression of the disease and UV intensity. The average UV index for the geographic area of residence at the time of disease onset was used …