Optimal Strategies to Help Diagnose Follicular Lymphoma
Insights From: Alexey V. Danilov, MD, PhD, Oregon Health & Science University; Carla Casulo, MD, University of Rochester, Wilmot Cancer Institute
Alexey V. Danilov, MD, PhD: For the diagnosis of follicular lymphoma, excisional biopsy is highly recommended. It is, in fact, optimal so we are able to obtain the necessary work-up. Core needle biopsies are sometimes possible if access to lymph nodes is difficult. However, it will be suboptimal, and not all diagnostic testing can be performed on core needle biopsies. When an excisional biopsy is obtained, a pathologist will order a panel of immunohistochemical stains, which will include such antibodies as CD5, CD10, CD20, and others. Follicular lymphoma is a CD10 lymphoproliferative disorder, and it needs to be differentiated from other types of lymphomas, including mantle cell lymphoma, chronic lymphocytic leukemia, and aggressive lymphomas, such as diffuse large B-cell lymphoma.
Follicular lymphoma is an indolent disorder, and morphology and extensive pathologic analysis of the excisional biopsy is very important for differentiating follicular lymphoma from diffuse large B-cell lymphoma, as the treatment will be different. Furthermore, excisional biopsy is necessary to document the grade of follicular lymphoma. There are 3 grades: 1, 2, 3a, and 3b. Grade 3b follicular lymphoma, in treatment, is typically approached as diffuse large B-cell lymphoma. Furthermore, grade 3a follicular lymphoma may also sometimes behave differently and respond differently to therapies. However, this is still the subject of ongoing investigation. Again, grading of follicular lymphoma is most optimal on excision biopsy of the lymph node.
In addition, for the staging of follicular lymphoma, once the diagnosis is established on a biopsy, we conduct imaging. Typically, the first type of imaging might be conducted by ordering computed tomography scans of chest, abdomen, pelvis, and sometimes, the neck. However, the key question for staging of follicular lymphoma is whether it is an early stage, such as 1 or 2, according to Ann Arbor Staging Classification, or an advanced stage 3 or 4 follicular lymphoma. While the distinction between stages 3 and 4 may not be as critical, diagnosing stage 1 follicular lymphoma or limited stage 2 follicular lymphoma is really important, as the approach to treatment of such follicular lymphoma will also differ.
For such limited stage follicular lymphoma, radiotherapy still remains the mainstay of treatment, with or without chemoimmunotherapy. Therefore, in those patients where limited stage follicular lymphoma is suspected, it is particularly helpful to rule out involvement by lymphoma outside of the initial area. If we suspect limited stage follicular lymphoma and propose to treat it with radiotherapy, I also perform staging with a bone marrow biopsy to rule out involvement of bone marrow by follicular lymphoma, as it is another frequent site that can be involved and change the course of management.