Have you noticed a lump in your neck or under your arm and wondered if this is something to worry about? Often, our lymph nodes (also called lymph glands) swell up in response to infection. More rarely, enlarged lymph nodes can be a sign of cancer. When are swollen lymph nodes cause for concern?
Your body contains about 600 lymph nodes, often in clusters, in various areas of your body. Common spots include your neck, on the face directly in front of the ears, under your arms, and in your groin area. They also can be found under your jaw, behind your ears, above your collarbone, and in your abdomen and legs.
Lymph nodes are normally pea-sized or smaller, unless they swell, which can happen in response to infection. They are part of your lymphatic system, designed to trap and flush out viruses and bacteria. When lymph nodes swell, it is lymphadenopathy. When nodes swell in one area of your body it’s localized lymphadenopathy. If nodes in more than one area of your body swell at the same time, it's generalized lymphadenopathy.
Most often, lymph nodes become enlarged when you are sick. Lymph nodes often swell near where an infection has occurred. So, if you have a sore throat from an infection, lymph nodes in your neck may become enlarged, for example. This can occur on both sides or just one side of your neck.
Reasons for lymph nodes to become enlarged include:
- Viral infections such as measles, chickenpox, AIDS, mononucleosis (Epstein-Barr virus), upper respiratory infections (like the common cold), and tonsillitis
- Bacterial illnesses like Lyme disease or strep throat
- Skin infections, such as from cuts, scratches or insect bites
- Immune system disorders, including lupus and rheumatoid arthritis
- Side effects from medications, such as the antiseizure drug phenytoin (Dilantin), or vaccines (in particular, the measles-mumps-rubella, or MMR vaccine)
- Leukemia (cancer that starts in the bone marrow or blood) or lymphoma (blood cancer that starts in the lymphatic system)
- Cancers that have spread (metastasized) from another area of the body to the lymph nodes
Other types of lumps can appear in your lymph glands, such as cysts (sacs of fluid). For example, what appears to be a swollen lymph node in your armpit can actually be a cyst caused by shaving or using antiperspirants. Another common type of lump that may appear in lymph glands is a lipoma—a noncancerous, smooth mass comprised of fatty tissue.
What are the differences between swollen lymph nodes due to infection and lumps that may be cancerous? Doctors recommend you examine your enlarged lymph nodes, keeping several factors in mind:
- Size. A swollen lymph node is unlikely to be bigger than about a half-inch around. On the other hand, suspicious lumps may be 1 or 2 inches in diameter, or even larger.
- Painfulness. Does it hurt to touch your swollen lymph node? Is it red or extra warm? These are indications it is in response to infection. Lumps that are painless present more cause for concern due to the possibility of cancer, though many noncancerous lumps are painless as well.
- Hardness. Is the lump easy to move? Or, when you push it, does it stay in place? Lumps that are cancerous tend to be rooted in place and not movable, while also feeling very hard, like a stone. A swollen lymph node tends to be softer and moves when you push it.
- Rate of growth. Generally, a lymph node that has swollen due to infection pops up quickly, does its job to expel the infection within a couple of weeks or so, and then recedes. But a lymph node that stays enlarged or grows for longer than about a month needs to be brought to your doctor's attention. (Sometimes, though, lymph nodes—especially in children—can stay somewhat enlarged for many weeks after their infection has cleared. When in doubt, contact your family practitioner.)
- No obvious reason for the swelling. If your lymph glands are larger than normal but you have none of the conditions outlined above, contact your doctor. This is especially true if you also have unexplained weight loss, night sweats, or fatigue, which can be signs of lymphoma or leukemia.
Keep in mind that most swollen glands or lumps under the skin are not cancerous. But it is better to see your doctor if you notice any symptoms of concern in order to be sure—and to catch any serious condition early, when treatment can be most effective.
