Dermatomyositis is connective-tissue disease that is characterized by inflammation of the muscles and the skin. Its cause is unknown, but it may result from either a viral infection or an autoimmune reaction. Up to 50% of the cases may be a paraneoplastic phenomenon, indicating the presence of cancer.
X-ray findings include dystrophic calcifications in the muscles.
There is a form of this disorder that strikes children, known as juvenile dermatomyositis.
"Gottron's papules", pink patches on the knuckles, are associated with this disorder.