High grade B cell lymphoma NOS

by Jason Wasserman MD PhD FRCPC and Phil Berardi MD PhD FRCPC
February 23, 2024

High grade B cell lymphoma NOS (HGBL NOS) is a type of cancer that starts in the white blood cells called B cells. These cells are part of the immune system and help protect your body from infections and diseases. “High grade” means that this type of cancer is likely to grow and spread quickly requiring prompt and aggressive treatment. “NOS” stands for “not otherwise specified”. This designation indicates that while the cancer is identified as a high grade B cell lymphoma, it doesn’t have enough unique features to classify it into a more specific category within this group of lymphomas.

What are common symptoms of high grade B cell lymphoma NOS?

The symptoms of high grade B cell lymphoma NOS can vary but often include:

• Swollen lymph nodes in the neck, armpits, or groin that are usually painless.
• Fever, chills, and night sweats.
• Unexplained weight loss.
• Fatigue.
• Loss of appetite.
• Shortness of breath or cough if lymph nodes in the chest are affected.

What causes high grade B cell lymphoma NOS?

The exact cause of high grade B cell lymphoma NOS is not well understood. However, it is believed to be related to genetic mutations in B cells that lead to their uncontrolled growth. Factors that may increase the risk include certain infections, immune system diseases, and exposure to specific chemicals.

What genetic changes are found in high grade B cell lymphoma NOS?

This type of lymphoma can have various genetic changes. Some common alterations include translocations (where parts of chromosomes have been rearranged), mutations in genes that control cell growth and death, and changes in the number of copies of certain genes. These genetic changes can help the cancer cells grow uncontrollably. However, none of the genetic changes identified to date are completely specific to this type of lymphoma.

What is the prognosis for a person diagnosed with high grade B cell lymphoma NOS?

The prognosis for high grade B cell lymphoma NOS varies depending on several factors, including the stage of the disease, the patient’s age and overall health, and how well the cancer responds to treatment. With appropriate and timely treatment, many patients can achieve remission, but the aggressiveness of the disease can make the prognosis more challenging compared to other types of lymphoma.

Microscopic features of this tumour

Under the microscope, high grade B cell lymphoma NOS is characterized by the presence of large, abnormal B cells that are dividing rapidly. These cells can vary in size and shape but generally look different from normal B cells. Pathologists often use the term “blastoid” to describe tumour cells because they resemble immature immune cells called blasts.

What other tests may be performed to confirm the diagnosis?

Immunohistochemistry

Immunohistochemistry (IHC) is a test used to see specific markers (typically proteins) inside cells. The results are often reported as positive (the cells are making the marker) or negative (the cells are not making the marker). The tumour cells in high grade B cell lymphoma NOS are frequently positive for markers expressed by normal B cells including CD19, CD20, and CD22. The tumour cells may also be positive for BCL2, BCL6, and CD10. The tumour cells are usually negative for CD34 and TdT.

Fluorescence in situ hybridization (FISH)

Fluorescence in situ hybridization (FISH) is a test that allows pathologists to see genetic changes inside cells. Pathologists use a variety of names including translocations, fusions, or rearrangements to describe these changes but they all mean essentially the same thing. These changes involve a piece of genetic material or DNA moving from its normal location on a chromosome to another part of the chromosome or an entirely different chromosome. As a result, a new gene is formed which alters the behavior of the cell.

Unlike other types of high grade lymphomas, high grade B cell lymphoma NOS does not typically show any specific translocations, fusions, or rearrangements and FISH is usually performed to rule out other types of lymphomas.

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