What is non-Hodgkin lymphoma?
Non-Hodgkin lymphoma (NHL) is a type of blood cancer. It affects white blood cells called lymphocytes. It is also called a cancer of the lymphatic system. This is because it starts in 
or other parts of the .
The lymphatic system is a system of thin tubes and lymph nodes that run throughout the body. Lymph nodes are bean shaped glands. The thin tubes are called lymph vessels or lymphatic vessels. Tissue fluid called lymph circulates around the body in these vessels. And it flows through the lymph nodes.
The lymphatic system is an important part of our immune system. It plays a role in fighting bacteria and other infections. And it tries to destroy old or abnormal cells, such as cancer cells.
The diagram shows the lymph vessels, lymph nodes and other organs. These make up the lymphatic system.
What is the difference between Hodgkin lymphoma and non-Hodgkin lymphoma?
There are 2 main types of lymphoma. They are called Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL).
Hodgkin lymphoma was named after the doctor who first recognised it. It used to be called Hodgkin's disease.
Hodgkin lymphoma has a particular appearance under the microscope. It contains cells called Reed-Sternberg cells. NHL looks different under the microscope and does not contain Reed-Sternberg cells.
Doctors need to tell the difference between Hodgkin lymphoma and NHL. They are two different diseases and the treatment for them is not the same.
There are more than 60 different types of NHL. They can behave in very different ways. Your doctor or specialist nurse will tell you about the type you have.
This video explains what lymphoma is and how it starts. And the difference between Hodgkin lymphoma and non-Hodgkin lymphoma. The video lasts just over 3 minutes.
What is lymphoma?
Lymphoma is cancer of the lymphatic system.
There are two main types: Hodgkin lymphoma and non-Hodgkin lymphoma - or NHL.
The lymphatic system is part of our immune system it helps us fight infections.
Understanding how it works may help you to understand what lymphoma is.
The lymphatic system is made up of a number of different organs, including the bone marrow, the spleen and the thymus gland.
It’s also made up of thin tubes and lymph nodes which contain lymph fluid.
Lymph nodes are sometimes called lymph glands.
The lymphatic system runs throughout the body.
The lymph nodes filter substances that travel in the lymph fluid.
They also contain lymphocytes, a type of white blood cell that helps us to fight infections.
There are two main types of lymphocytes: B cells and T cells.
They work in slightly different ways.
A lymphoma starts when the lymphocytes become abnormal.
The abnormal cells make more abnormal cells, which means you have many more lymphocytes than usual, but they can’t fight infections as well as they should.
These abnormal cells circulate around the lymphatic system and start to build up in the lymph nodes forming a lump.
You may notice swollen glands in your neck, your armpit, or your groin.
But they can collect in other parts of your body that you can’t feel, including your lungs, liver and spleen.
It's important that your doctor finds out which type of lymphoma you have – Hodgkin lymphoma or non-Hodgkin lymphoma as they are two different diseases.
The most common type of Hodgkin lymphoma is called classical Hodgkin lymphoma.
It starts in B cells and contains Reed-Sternberg cells.
So, finding out if these particular cells are present confirms it's this type of lymphoma.
Non-Hodgkin lymphomas are the more common type of lymphoma.
There are many different types of non-Hodgkin lymphomas and they are grouped into either high grade or low grade.
High grade are faster growing and low grade NHL’s grow more slowly.
Your doctor will tell you the type of lymphoma you have and what this means for you.
It depends on the type of lymphoma you have as to what treatment you need.
You might have drug treatment, radiotherapy, or a stem cell transplant.
For more information about lymphoma, the tests you might have, and treatments visit cruk.org/ about-cancer/lymphoma
How does non-Hodgkin lymphoma develop and affect you?
You develop lymphoma when white blood cells () divide abnormally and grow out of control.
Usually, we have just the right number of each type of cell. This is because cells produce signals to control how much and how often the cells divide. But sometimes cell division can get out of control.
Normal white blood cells have resting time when they aren't dividing and making new cells. But if you have lymphoma, some of your white blood cells don't have any resting time. They divide continuously, so you produce too many. And the cells don't naturally die off as white blood cells normally do.
These cells start to divide before they are fully mature. So they can't fight infection as normal white blood cells do.
The abnormal white blood cells start to collect in the lymph nodes. Or they collect in other places such as the bone marrow or spleen. They can then grow into tumours and begin to cause problems in the lymphatic system, or in the organ where they are growing. For example, if a lymphoma starts in the thyroid gland it can affect the normal production of thyroid hormones.
Where does non-Hodgkin lymphoma start?
You can get NHL just about anywhere in your body. This is because the lymphatic system runs through your whole body. It most often starts in the lymph nodes and can affect several groups of lymph nodes around your body.
You can also find lymphoma in other body organs outside the lymphatic system. For example, the stomach or bones.
Lymphoma that starts outside the lymphatic system
NHL can begin to develop outside the lymph nodes. This is called primary extranodal lymphoma.
It can begin in almost any part of the body. The diagram below gives some examples of where lymphoma can start or spread to in the body.
Other cancers that have spread to the lymph nodes
Most types of cancer can spread to the lymph nodes. But they are not lymphoma. Lymphoma is cancer that starts in the lymph nodes.
For example, if breast cancer spreads to the lymph nodes in the armpits it does not become lymphoma. The cancer cells that have spread to the lymph nodes are still breast cancer cells. So they are treated as breast cancer.
If your cancer has spread to the lymph glands (and is not lymphoma), you should look for information about that type of cancer.
Types of non-Hodgkin lymphoma
There are many different types of NHL. These types can be grouped (classified) in several different ways. Doctors look at different factors to group non-Hodgkin lymphoma (NHL) and find out your type.
B cell and T cell
NHL begins in a type of white blood cell called a lymphocyte. There are two types of lymphocytes. These are B cells and T cells. So you can develop a B cell lymphoma or a T cell lymphoma. There are then different types of B cell and T cell lymphomas.
High grade and low grade
Lymphomas are often grouped together as either high grade or low grade. The grade refers to how quickly they are likely to grow and spread.
The 2 groups are low grade (slow growing) and high grade (grow more quickly). The different grades of NHL are treated in slightly different ways.
NHL in children
The treatment for NHL in children is slightly different to NHL in adults. So while some of the information here is useful, you do need to be careful. We have separate information about NHL in children.
How common is non-Hodgkin lymphoma?
Around 14,200 people are diagnosed with NHL each year in the UK. This makes it the 6th most common type of cancer in adults. 4 out of every 100 cancers diagnosed (4%) are NHL.
Who gets non-Hodgkin lymphoma?
It is more common in older people. Around 35 out of 100 (around 35%) of people diagnosed with NHL are aged 75 and over.
