One of the most common questions we are asked in our practice is what is that lump in your child’s neck, or behind the ear, or on the back of the head, or even in the crease where the leg meets the body?

Usually the question comes with some sense of worry, could that lump turn out to be something serious.

The most common answer to these questions, by far, is that the lump is a normal part of everyone’s body- the lymph node.  So we thought it would be of interest to know what a lymph node is, and how to know if a lump is a normal lymph node, or something else.

To understand what a lymph node is, we should mention something about the lymph system that these nodes are part of.

Most everyone is familiar with one vascular system, the one where the heart pumps blood out into arteries that then deliver the blood back to the heart via the veins.  As most people know, the arteries branch into smaller and smaller blood vessels, eventually thinning out into the filigree nets of capillaries.  Blood flowing in the capillaries leads to fluid seeping into the tissues these nets feed, and then the fluid is absorbed back into the tiny veins in all tissues, leading to it going back to the heart for another round.

But a small bit of fluid that seeps out of the capillaries remains out of the circuit, it gets absorbed by another network of tiny vessels that deliver this extra fluid into ever larger vessels, eventually delivering it all back to a very large vein near the heart.  This network of collected fluid is called the lymphatic system, and lymph is the name of the fluid collected and returned to the heart.  Lymph is not blood, it is all fluid.   

Along the way as the lymph fluid travels into ever-larger lymphatic vessels before ending up in the heart, the fluid flows through a small lump of tissue.  That small lump is a lymph node.  There are about 500 or more lymph nodes in every human body.  Each of these little lumps serve two main functions:

1.  They read the lymph fluid to see if the part of the body the lymph is from contains any germs or other cells of concern.

2.   If the node finds germs or other cells to destroy, the node enlarges to manufacture enough antibodies and white blood cells to destroy the unwanted intruders.

The node itself contains a complex labyrinth of tissues which contain a huge number of immune system cells that can do both these functions:  monitoring and defending.

This makes sense.  After all, what does our immune system do?  It looks for cells that can cause trouble and destroys them.

The best way to think about lymph nodes is that they are factories.  What to do they make?  Antibodies and white blood cells.  Why do they make these materials- to fight off infections and other threats.

So, if there are no infections to require lots of antibodies or white blood cells, the factory lies dormant, and can remain small.

But if a germ invades, the factory comes to life and starts making a huge amount of material to fight it off.  The node can only do that by getting bigger.  It stays big after the effort succeeds, to continue making material to keep the body immune to the last threat.

After many months of no threat, the node can once again go dormant, which makes it slowly get smaller.

Most of the 500 or more lymph nodes in the body are deep inside the main body, but there are two areas they can be seen or felt very easily:  the head/neck area, and in the crease where the leg meets the body.

By far the most common area we can see our lymph nodes get bigger and smaller is around the head.

There is a chain of them along the front of either side of the neck, along the lower edge of the jaw line, along the back of either side of the neck, behind the ears, and on the back of the head.

Inside the mouth are 2 pair of very famous lymph nodes, the tonsils and adenoids.  If you can think of the roof of the mouth meeting the back of the throat, the lymph nodes on top of the roof of the mouth near the back of the throat are called adenoids. And, the lymph nodes on the back of the throat are called tonsils.

All these lymph nodes do the same thing, the tonsils have their own name because they are visible with the unaided eye..

Now, every person born gets colds and these infections turn the lymph nodes of the head and neck on, making them grow to make their protective goods.  When they enlarge enough to feel or see, they are often called swollen glands.  Essentially every child will have their head/neck lymph nodes become enlarged to fight off such infections.  The “swollen glands” typically remain enlarged for quite some time, but after many months, slowly shrink, often back to the small size they started from a size so small it cannot be seen or felt.

If a lymph node enlarges to defend a person from an infection, there is no cause for concern, just the opposite.  It’s a wonderful thing to have a working immune system, and for it to work.  And that’s all a lymph node enlarging to fight off an infection is about.  It is very normal.

There are two situations when an enlarging lymph node no longer is normal.

One is if the node itself falls prey to a bacterial infection.  The nodes screen for bacteria and so now and then a living bacteria lodges in the node and turns it into an abscess.  This is fairly unusual, the vast majority of children never experience this.  But here is how you would know this is happening:

the node gets incredibly big, and dramatically painful. Often infected nodes feel bouncy like a water balloon, but the key sign of trouble is getting far, far bigger than the usual swollen gland, and amazingly painful.

The other way nodes can go bad is incredibly rare, and yet is the one outcome all fear somewhere in the back of our minds- cancers- particularly leukemias and lymphomas.  The best reassurance that an enlarging lymph node is not a sign of cancer is that this is an incredibly rare event.  Most pediatricians may see this happen less than five times in a 50 year career!  

But a more useful sign that an enlarged node is not cancer is that cancers continue to grow.  So if a node suddenly appears, and gets bigger, and then stops getting bigger, and never gets bigger than 1/2 an inch across, you are safe.  Nodes that are cancers don’t stop growing, and almost always get bigger than 1/2 an inch across.

Be sure to know, though, that many simple, healthy, activated nodes, growing to fight off an infection, can get bigger than 1/2 an inch across, but they too stop growing.

2.  Everyone has hundreds of lymph nodes as a normal part of our bodies.  Put them all together and they constitute much of what we call the immune system.  
3.  Lymph nodes monitor all body spaces for evidence of infection and other worrisome cells, and if they find them, they destroy them in that space.
4.  Lymph nodes typically lie dormant most of the time, but now and then they activate to make the antibodies and white cells necessary to defend their space.  When they do this they get much bigger and even a bit sore.  Not only is that normal and OK, but it is necessary for life.  If we didn’t have lymph nodes, or if our lymph nodes didn’t activate and get big when needed, we would have no immune system.
5.  The two main reasons to think your child’s lymph nodes are big for a worrisome reason are:
      a.  If they get very, very tender, red, and even feel fluid-filled.
      b.  If they keep growing, rather then enlarge and stay the same size for many months
6.  Both of these worrisome signs are very unusual, by far the vast majority of enlarged lymph nodes, or swollen glands, stay about the same size, do not get very red or very, very tender.
7.  So unless the unusual signs appear, enjoy your lymph nodes, they are what keeps us safe.

To your health,
Dr. Arthur Lavin

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