One of the earliest visual indications that a person might have lymphoma is a swollen lymph node, normally somewhere in the neck or collar bone, that is found to be painless and to have a rubbery feel to it, and is not associated with any known infection, such as a cold.
So what exactly are lymph nodes anyway, and what purpose do they serve in the human body?
Within the human body is a network called the lymphatic system. It includes lymph vessels (like blood vessels) and lymph nodes. The network of vessels runs throughout the entire body, and what it does is it collects debris and other harmful substances found outside of the bloodstream and in the body's tissues. This network uses a clear liquid called lymph to pick up and carry this debris away from the tissues.
The lymph fluid found in the lymph vessels comes from out of the walls of the body's tiniest vessels, the capillaries. It "bathes" the body's tissues and, in doing so, collects that debris. At that time, the lymph vessels collect the contaminated fluid.
This lymph fluid, carrying within it the debris it has collected from various parts of the body, has to do something with it; it can't just cycle it through the body forever. That's where the lymph nodes come in. Lymph nodes are little filtering stations for the lymph fluid. As the fluid passes through a node, the node filters out the debris from the lymph, allowing the now debris-free lymph to continue its work in the body.
The debris caught in the lymph node is now subject to attack by the body's immune cells — B-cell and T-cell lymphocytes. The immune cells destroy the harmful debris, which contributes to a person's overall health by fighting any possible infection that this harmful debris could cause.
Each person has 200-300 lymph nodes in his or her body. There aren't very many lymph nodes to be found in the arms and legs, though some are indeed there. Rather, most lymph nodes are clustered together, and these clusters can be found in the groin, the stomach, the chest, the underarms, the shoulders, and throughout the neck. There are even some found behind and in front of our ears.
Lymph nodes play an important role in cancer. When the white blood cells that fight infection, known as lymphocytes, become cancerous, we call this lymphoma. It is not as common as when cancerous cells from another region find their way to the lymph nodes.
When a cancer from another "primary" site (e.g., the pancreas, testes, etc.) has been diagnosed and is then found in the lymph nodes, it generally indicates that the cancer has successfully metastasized, or spread, through the body. This is not considered a lymphoma, and it will be treated differently than lymphomas are treated, depending on the primary site.