I have a small, smooth red lump on my right upper arm. It is about 1cm squared in size and slightly raised. It doesnt itch and doesnt irritate. Ive had it for many years and it hasnt changed at all. Links to what it looks like are:  WWW.WWWW.WW        and         WWW.WWWW.WW
Thanks for your question on Chat Doctor. I can understand your situation and problem. Following are the possible causes for your painless, stable upper arm lump. 1. Hematoma 2. Lipoma 3. Desmond (less likely) 4. Fibroid (less likely) Since your swelling is not causing you any trouble like not painful, not enlarging in size, non-itchy, not restricting the movements etc., no treatment is required for it. So don't worry about this swelling.