Non-Hodgkin’s Lymphoma (b-cell NHL)

Lymphoma is cancer that begins in cells of the lymph system. The lymph system is part of the immune system, which helps the body fight infection and disease. Because lymph tissue is found all through the body, lymphoma can begin almost anywhere. The two main types of lymphoma are Hodgkin’s lymphoma and non-Hodgkin’s lymphoma (NHL). These can occur in both children and adults.

There are many different types of NHL that form from different types of white blood cells (B-cells, T-cells, NK cells). Most types of NHL form from B-cells. NHL may be indolent (slow-growing) or aggressive (fast-growing). The most common types of NHL in adults are diffuse large B-cell lymphoma, which is usually aggressive, and follicular lymphoma, which is usually indolent. Because lymph tissue is found throughout the body, adult non-Hodgkin lymphoma can begin in almost any part of the body. Age, gender, and a weakened immune system can affect the risk of adult non-Hodgkin lymphoma.

The National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program estimates 80,550 people in the United States will be diagnosed with non-Hodgkin lymphoma in 2023, and 20,180 will die of the disease.

Source: https://seer.cancer.gov/statfacts/html/dlbcl.html and https://www.aacr.org/patients-caregivers/cancer/non-hodgkin-lymphoma/

FDG PET/CT (Non-Hodgkin’s lymphoma) Visualized at two time points

National Comprehensive Cancer Network© (NCCN©) comments on PET/CT Applied to B-Cell Lymphomas

“PET has a high positivity and specificity when used for the staging and restaging of lymphoma. PET is nearly universally positive at diagnosis in Diffuse Large B-Cell Lymphoma (DLBCL), Follicular Lymphoma (FL), and nodal Marginal Zone Lymphomas (MZL), but less sensitive for extranodal MZL. However, a number of benign conditions including sarcoid, infection, and inflammation can result in false-positive PET scans, complicating the interpretation. Lesions <1 cm are not reliably visualized with PET scans.

Although PET scans may detect additional disease sites at diagnosis, the clinical stage is modified only in 15% to 20% of patients and a change in treatment in only 8% of patients.” (page 162)

“PET/CT scans are more accurate than CT scans alone in the detection of disease in patients with indolent lymphomas and several studies have reported high sensitivity (94%–98%) and specificity (88%–100%) for PET/CT scans for indolent lymphomas. PET scans may also be useful in identifying occult sites of disease and detecting histologic transformation of FL to DLBCL.

Standard fluorodeoxyglucose (FDG) uptake values (SUVs) on PET have been reported to be higher among transformed than non-transformed indolent lymphomas. PET scans do not replace histologic confirmation of the diagnosis; however, if there are sites with discordantly high FDG avidity, these represent the most likely sites of histologic transformation. High SUVs on PET scan should raise the suspicion of histologic transformation to DLBCL, and can be used to direct the optimal site of biopsy for histologic confirmation.” (page 182-183)

Permission Pending from the National Comprehensive Cancer Network, Inc. 2023. Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for B-Cell Lymphomas Version 5.2023 — July 7, 2023. © National Comprehensive Cancer Network, Inc. 2023. All rights reserved. Accessed August 15, 2023 To view the most recent and complete version of the guideline, go online to NCCN.org. Link https://www.nccn.org/professionals/physician_gls/pdf/b-cell.pdf (page 162, and page 182-183 of 324).