Symptoms of dermatomyositis are almost identical to those of polymyositis. The diseases differ in that dermatomyositis is accompanied by a skin reaction that is manifested as a rash, commonly seen over the face, chest, and knuckles. The other major difference between the two disorders is that one-third of the cases of dermatomyositis occurring in older individuals is associated with an undiagnosed or a known underlying cancer. Once the diagnosis of dermatomyositis is made, attempt at ruling out the presence of a cancer should be implemented. These procedures include a chest x-ray, mammogram in women, prostate exam in men, flexible sigmoidoscopy, and possibly a CT scan of the abdomen with contrast.