Bruce Cheson, MD: Follicular lymphoma is 1 of more than 60 types of B-cell lymphomas. We distinguish it from the other forms of lymphomas in a variety of ways—first of all, by morphology. We look at it under the microscope, and we can see that the lymph node is generally effaced by some aberrant lymphoid follicles. Then we do other tests, such as immunohistochemistry and flow cytometry, which give us the spectrum of antigens on the lymphoid cells. We know that follicular lymphoma characteristically expresses CD20, CD10, and CD19, and doesn’t express some other antigens that might be more consistent with other forms of lymphoma. So, you put together the whole package of morphology, immunology, and you can even throw in some genetic markers as well—that it’s positive for BCL2, for example—and you get the picture of follicular lymphoma.

Anas Younes, MD: When you try to diagnose a patient with lymphoma in general, including follicular lymphoma, it is very important to obtain adequate tissue specimens for establishing accurate diagnosis. That can be done either through excisional biopsy or through core needle biopsy. A fine-needle aspiration is not adequate to diagnose the majority of lymphoid malignancies. You can tell whether it’s lymphoma or not in many cases, but you would not be able to subclassify it based on an FNA. That’s why we need either a core biopsy or an excisional biopsy.

Bruce Cheson, MD: The staging criteria for lymphoma for decades, since about 1971, have been the Ann Arbor classification. These were primarily for Hodgkin’s lymphoma because, in those days, chemotherapy was of little use for non-Hodgkin’s lymphoma. And these were used to tell the radiation therapist where to point their beam. Over the years, this has been applied to non-Hodgkin’s lymphoma as well. In 2016, with the Lugano classification, we updated the staging system for non-Hodgkin’s lymphoma. It’s similar to the Ann Arbor system, but a bit more contemporary and user-friendly.

Transcript Edited for Clarity