<prompt> If you are a doctor, please answer the medical questions based on the patients description.I have just discovered a large lump in my 6 yr old sons neck, to the left towards the back of his jaw. He says he feels fine, he doesnt have a temperature and is eating as usual. I would say however that he has been looking pale for a while and has dark circles under his eyes. He has a bakers cyst on the back of his knee, which was diagnosed and scanned about a month ago.I am very concerned and have just called our GP who can see him this afternoon. Lymphoma and Leukemia run in my family.Yours,Jane Maben  <response>: Hi. Thanks for your query and an elucidated history. History noted. I would suggest for a simple test of FNAC fine needle aspiration cytology. This will help immensely to confirm or rule out a sinister problem of lymphoma. Blood picture would help for leukemia. Towards the back of the jaw can be more of a parotid swelling than the lymph node. The treatment will be totally dependent on what will be reports. 