An Expert Defines Diffuse Large B-Cell Lymphoma (DLBCL)
An Expert Defines Diffuse Large B-Cell Lymphoma (DLBCL) from Patient Empowerment Network on Vimeo.
What is diffuse large B-cell lymphoma? Dr. Justin Kline defines DLBCL from symptoms to staging and explains how the condition progresses through the body.
Dr. Justin Kline is the Director of the Lymphoma Program at the University of Chicago Medicine. Learn more about Dr. Kline, here.
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Let’s start by understanding what DLBCL is and how it progresses. How would you define DLBCL?
Well, diffuse large B-cell lymphoma is a malignancy of a normal counterpart cell called a B-cell, which is part of our immune system. Its job is to make antibodies, to help protect us from various types of infections. Diffuse large B-cell lymphoma, or DLBCL, initiates when normal B-cells acquire changes in their genetic machinery, like any cancer. And DLBCL is the most common form of non-Hodgkin lymphoma. We classify it as aggressive, as an aggressive lymphoma, which means if left untreated it tends to grow pretty quickly.
How is it typically diagnosed?
Well, it varies. But like any cancer, a diagnosis requires some sort of a biopsy, either a surgical removal of a lymph node or a needle biopsy of a lymph node or another structure where the tumor seems to be growing.
How does somebody know if they have DLBCL?
Well, there are certain symptoms that are more common amongst folks with DLBCL. And they’re not specific to DLBCL, they can be seen in other lymphomas, but they include symptoms like fatigue that’s unrelenting, unintentional weight loss, sometimes fevers, typically at similar times throughout the day, drenching night sweats, swollen lymph nodes, and then certainly pain in any area of the body that comes and doesn’t go. Those are some of the general symptoms.
And how does the condition progress?
Well, as I mentioned, DLBCL tends to be an aggressive lymphoma, so sometimes folks will notice enlarged lymph glands that continue to grow and grow and grow. Sometimes they’re painful, sometimes not so much. DLBCL, it can really grow anywhere, so we think of it as a lymphoma and so involving lymph nodes, but DLBCL can grow in any organ, even outside of lymph nodes. And so it sometimes progresses locally, but it also can spread and start to grow in other areas of the body.
And how is it staged, Dr. Kline?
Well, there’s a special staging system for all lymphomas that is somewhat similar to what folks might think of with solid tumors like a breast cancer, a lung cancer. But in other ways, it’s different.
The staging tools for DLBCL are really most importantly PET scans and CT scans, really PET scans and in some cases bone marrow exams or bone marrow biopsies. The PET scan is a very sensitive scan that uses radioactive glucose to identify very sensitively where in the body lymphoma might be growing, because lymphoma cells really preferentially prefer to use glucose as their primary energy source. So, they preferentially take up the radioactive glucose that’s given through the vein before the PET scan is taken.
As I mentioned, in some cases, a bone marrow test is also done, although less and less frequently. Which is good, because that’s a more invasive and uncomfortable test. And so folks who have early stage DLBCL that typically involves one lymph node group, like for example, a lymph node in the neck or several lymph node groups on the same side of the breathing muscle, of course you can’t see my breathing muscle here, called the diaphragm.
Those are stage I and stage II DLBCLs. stage III DLBCLs are those that involve lymph nodes on either side of the breathing muscle, so in other words, lymph nodes involved in the neck and then maybe in the groin area, where stage IV DLBCLs are those that involve sites outside of lymph nodes like the liver or the lungs or the bones.
What are the subtypes of DLBCL?
Well, that’s a good and somewhat complicated question. So there, probably most importantly, there’ve been two subsets, if you will, of DLBCL identified, and they really have to do with where along the normal maturation course a B-cell becomes lymphoma or where the DLBCL develops in that normal maturation course. Some DLBCLs arise from what we call germinal center B-cells, which are B-cells that are sort of just seeing their natural antigen or what they’re supposed to recognize.
And then there are DLBCLs that arise in more differentiated or more mature B-cells, and those are called activated B-cell type DLBCLs. So, there’s germinal center and activated, the B-cell type DLBCLs. And I don’t know that that’s super important for your listeners to know, but it is important because these two subtypes of DLBCL are driven by largely separate mutations or alterations in the DNA, and they also respond differently to initial treatment. There are other rare subtypes that involve specific mutations and genes like MYC and BCL2, and these are the so-called double-hit lymphomas. They’re officially classified as high-grade lymphomas, but they’re very similar to DLBCLs. There are other rare subtypes of DLBCL, for example, a type that comes on typically in young men and women called primary mediastinal B-cell lymphoma.
But I think for the sake of simplicity, the most common two subtypes are the germinal center derived and then the activated B-cell type of DLBCL.
All right. That’s good to know, thank you. It helps us understand the disease a little bit better.