 Features of the medical history may point to the cause, such as the speed of onset of swelling, pain, and other constitutional symptoms such as fevers or weight loss.For example, a tumour of the breast may result in swelling of the lymph nodes under the arms and weight loss and night sweats may suggest a malignancy such as lymphoma.In addition to a medical exam by a medical practitioner, medical tests may include blood tests and scans may be needed to further examine the cause.