Polymyositis is a rheumatic disease, such as psoriatic arthritis, which causes inflammation, pain and weakness in the muscles. Its origin is unclear but may be caused by an autoimmune reaction or infection of a muscle. Polymyositis is chronic, it affects the whole body and general symptoms are muscle pain and weakness, shortness of breath, fatigue and tiredness walking, fever and weight loss, among others. The disease has no cure, but the patient can regain muscle strength steroid. With this therapy can reduce symptoms and provide a normal life for the sick. If this treatment does not work, the condition can be controlled with immunosuppressant. In some cases, polymyositis is associated with a tumor, in which case it is necessary to proceed to remove it.