A swollen lymph node like can have "n" different causes. I would run an HIV test and would do a biopsy as well.
All the best.
There are lots of lymph vessels and nodes in the neck (it is a main collection site for lymph fluid). It could be a blocked/swollen lymphnode (endema). If it is, it will reduce with frequent, regular massage. Massage downwards and firm enough that the skin stretches (light stroking does nothing). You must massage for a minimum of 10 mins each time (at least once a day). Do not over do it at first, it is likely to hurt iof it has been there for that long. Also investigate his diet (green lesfy vegetables and low fat are key) and the amount of arm exercise he gets (sitting at a keyboard all day is very bad).
If it been there for 3 or 4 years it is really unlikely to be cancer because he would have other symptoms.
read below:
When functioning properly the lymphatic system effectively cleanses the tissues, aids in cellular repair, and eliminates toxins. When this system is blocked, infection-fighting material is prevented from destroying germs and cell-nourishing elements are prevented from reaching our blood. As a result, germs grow, our blood loses needed protein, the immune system falters, and we become defenseless against attacks by viruses, fungi, and bacterium.
As a circulatory system, optimal flow must be maintained within the lymphatic system. Unlike the blood, whose circulation is driven by the pumping of the heart, the lymph does not have its own pump. It is propelled by three means: the movement of muscles, the nerves which create subtle pulsations, and the fluid pressure within the system. Lymph fluid is cleansed by the liver, kidneys, and heart. It eliminates its toxic load through the elimination channels of the body - urine, bowel, skin, and lungs.
What are the causes of lymphatic congestion? They include poor lifestyle such as inactivity and improper diet, infections, injuries, surgery (scar tissue and adhesions), emotional stress states, environmental toxins, hormone imbalance, and the normal aging processes.
Poor lymphatic drainage can contribute to a wide range of dysfunction in the body and lack of vitality. If fluid concentrates in specific areas, it is referred to as edema. If there is impaired function along the entire lymph system, it is referred to as congestion. When edema or congestion is long lasting, blockages can form and cause a backup in the flow of lymphatic fluid.
As a consequence, toxic cellular waste cannot effectively be released from the body and the immune system may not function at its optimum. Visible signs of congestion are weight gain, diminished appearance and premature aging, such as skin breakouts, facial edema, dark circles at/around the eyes, dry, wrinkled or sallow looking skin, spider veins, and cellulite.
This could be a NUMBER of things including cancer, however, he needs to be assessed by an ACTUAL physician and proceed from there.