If it is caused by the increase of muscle, you can reduce the activity of the upper arm, don’t do sports exercise, the muscle can gradually shrink down, if necessary, go to the regular medical cosmetology department, give the muscle injection drug to make the muscle shrinkage to achieve the purpose of the thinning of the upper arm. But if it is pathological changes, the upper arm has a swelling, such as leiomyosarcoma, etc., you need to go to the hospital in time to perform ultrasound and make clear, if you find a swelling, timely surgical resection and sent to the pathology examination. If there is localized thrombosis, it is necessary to give deconcentration, expansion, thrombolysis and other treatments. If it is caused by too much fat, you can carry out upper arm exercise, diet control, do not eat high-fat food, such as cream cake, etc., appropriate intake of fiber-rich food, such as vegetables, etc., if necessary, can also be liposuction treatment.