How doctors group non-Hodgkin lymphomas

There are many different groups and types of non-Hodgkin lymphoma (NHL).

Doctors find out your type by looking at lymphoma cells under a microscope. Knowing your type means they can plan the best treatment for you.

Doctors group different types of NHL together depending on how they develop or how they behave. They look at several different factors including:

• the type of white blood cell affected (B cell lymphocyte or T cell lymphocyte)
• how fast the cells grow (grade)
• what the cells look like under the microscope

The name of your type of NHL might also depend on where the lymphoma starts in your body.

Systems for grouping NHL

Understanding how doctors group (classify) the different types of NHL can be difficult. There are more than 60 subtypes of NHL.

Various systems for classifying lymphomas into groups have been used over the years. The latest is the World Health Organisation classification of 2022. We give a simple description of the groups in this section.

Tests to find out your type

Your doctor finds out which type of NHL you have by removing part, or all of a lymph node, and sending it to the laboratory. This is called a biopsy. A specialist doctor (pathologist) examines it under a microscope.

The pathologist examines the cells to see:

• the type of cell affected (B cell or T cell)

• the grade of your NHL (how fast it grows)

• what the cells look like under a microscope

• which proteins (markers) are on the surface of the lymphoma cells (immunohistochemistry)

• whether there are certain gene changes in the lymphoma cells (cytogenetics and molecular analyisis)

Type of white blood cell - B cell or T cell

Lymphomas develop from a type of white blood cell called lymphocytes. Doctors group NHL depending on which type of lymphocyte it starts in. There are two types of lymphocytes:

• B-cell lymphocytes - B-cell lymphoma develops from an abnormal B-cell lymphocyte
• T-cell lymphocytes - T-cell lymphoma develops from an abnormal T-cell lymphocyte 

The most common types of B-cell lymphoma are:

• diffuse large B-cell lymphoma (DLBCL)
• follicular lymphoma (FL)

Less common types include:

• marginal zone lymphomas
• lymphoplasmacytic lymphoma (Waldenström’s macroglobulinaemia)
• mantle cell lymphoma
• burkitt lymphoma
• primary mediastinal large B-cell lymphoma
• small lymphocytic lymphoma

Types of T-cell lymphoma include:

• anaplastic large cell lymphoma
• peripheral T-cell lymphoma
• primary skin (cutaneous) lymphoma
• angioimmunoblastic lymphoma

Grades of NHL

Doctors sometimes put NHL into 2 groups, depending on how quickly they are likely to grow and spread. This is the grade. The 2 groups are low grade and high grade. 

The grade of your NHL affects your treatment plan.

Low grade NHL tends to grow very slowly. Doctors call them indolent lymphomas. Follicular lymphoma is the most common type of low grade lymphoma.

High grade NHL tends to grow more quickly than low grade NHL. Because they grow quickly your doctor might call your lymphoma an aggressive type. Diffuse large B cell lymphoma is the most common type of high grade NHL. 

What the lymphoma cells look like

In the laboratory a pathologist looks at the cells under a microscope to see if they are:

• large or small

• grouped together in structures called follicles (follicular type) or spread out (diffuse type)

Low grade NHL tends to have small cells that are grouped together.

For example, follicular lymphoma cells usually develop in clumps called ‘follicles’. It is a low grade lymphoma. 

And diffuse large B-cell lymphoma (DLBCL) cells are larger than normal, healthy B cells. The abnormal cells are spread out (diffuse) rather than grouped together. It is a high grade lymphoma.

Remember some people might use the word diffuse to describe NHL that is widespread in the body. This is not the same as the type of NHL called diffuse large B cell lymphoma.

Where NHL starts in your body

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.

NHL can also begin outside the lymph nodes. Doctors call this primary extranodal lymphoma. For example NHL can start in the stomach or bowel.

Your treatment still depends on the type of lymphoma cells. So if diffuse large B cell lymphoma (DLBCL) starts in your stomach, you have DLBCL treatment. This is different to stomach cancer treatment.