Hi! Good evening. I am Dr Shareef answering your query. Possibly your son might have had some kind of trivial trauma which he did not remember, but sustained a hematoma which might be resolving now. You can wait and watch the lesion. This might get dissolved completely. If it persists or increases, then I would advise you to get is assessed clinically by a general surgeon who might go for an FNAC if need be to arrive at a diagnosis. I hope this information would help you in discussing with your family physician/treating doctor in further management of your son s 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.