Dear doctor, My aunt has a non-painful lump in one of her arms (upper side) for around two years now. Lately, the lump has become very painful what could be the problem? Pamela Dear Pamela, A painful lump on one side of the arm could be due to a bacterial infection. And in such cases it is very painful. However, if that was the problem, it would have been filled with pus and burst by now considering that she has had it for 2 years. There would also have been associated fever and a small painful swelling could have formed under the arm or around it due to drainage of the infection in surrounding lymphatics. Any trauma to the bone or soft tissues over the area in the arm can cause swelling. The swelling could be due to collection of blood or inflammation or tear of soft tissues. Initially it may be small but due to strain caused by constant use of the arm it may increase in size. Gradually it may become more and more painful. Secondary infection or inflammation over the injury can also cause it to increase in size and become painful. Wear and tear over and around a joint can cause small fluid filled swellings, i.e. cysts. Sometimes there may be small cysts present since birth, which may increase in size over time due to wear and tear. At times a benign or malignant tumor can present as painless swelling over the arm. This can also increase in size and become painful over time. The tumor may be primarily at this site or may have spread from some surrounding structure. Diagnosis of the cause of swelling can be ascertained by clinical history and examination. Aspiration of the fluid present if any and examination of the fluid can help to know the nature of the swelling. A biopsy of the soft tissue is also useful.Treatment of the underlying cause can cure the swelling. Even malignancy in early stages is curable.
