<s>[INST] My daughter has an indentation in her upper left arm. It is about the size of a quarter. It appeared all of a sudden with no known injury, but is slightly painful when lifting or pushing on it. An MRI was done and the tech said there is a knot under it. We do not have official results yet. Any idea what it could be? [/INST] Hi ! Good evening. I am Dr Shareef answering your query. I would advise you to consult a general surgeon along with your reports, as it is not possible to opine on it simply on the MRI report without a clinical examination.  If the MRI is inconclusive, there may be a need for a FNAC (fine needle aspiration cytology) for a histological diagnosis. The surgeon has to decide on this investigation. Wish your daughter an early relief of the problem.Please do not hesitate to ask in case of any further doubts.Thanks for choosing health care magic to clear doubts on your health problems. Wishing you an early recovery. Dr Shareef. </s>