Follicular Lymphoma

At a Glance

Follicular lymphoma is one of the most common B-cell lymphomas, accounting for approximately 20% of all adult lymphomas in the United States and Western Europe. It is primarily a disease of middle age to older adults, with a median age in the sixth decade and only very rarely occurring in the pediatric age group. It is a neoplasm of follicle center (germinal center) B cells. Patients usually present with lymphadenopathy.

What Tests Should I Request to Confirm My Clinical Dx? In addition, what follow-up tests might be useful?

The diagnosis is optimally made on an excisional biopsy of an enlarged lymph node (a needle biopsy is often not able to provide the broad architecture view important in diagnosis and classification of follicular lymphoma). The normal architecture of the lymph node is replaced by follicular or nodular collections of small cleaved cells (grade 1), a mixture of small cleaved and large lymphoid cells (grade 2) or predominately large lymphoid cells (grade 3). The most recent 2008 World Health Organization (WHO) classification has recommended combining grades 1 and 2, reflecting the difficulty in reproducing the distinction between grades 1 and 2 among pathologists.

If a lymphoma is suspected prior to biopsy, a fresh sample of the lymph node is often sent for flow cytometry and is helpful in demonstrating a monoclonal population of B cells that have co-expression of CD10. In the absence of the availability of fresh tissue for flow cytometry, immunohistochemistry studies performed on sections of the paraffin embedded fixed tissue will demonstrate the cells in the follicles to be positive for CD20 (B cell antigen), CD10, BCL-2, and have a relatively low percentage of cells positive for Ki-67 (proliferating antigen). It is important at the time of diagnosis and in any subsequent biopsies to be certain that there is no complement of diffuse large B cell lymphoma.

Are There Any Factors That Might Affect the Lab Results? In particular, does your patient take any medications – OTC drugs or Herbals – that might affect the lab results?

Additional tests or biopsies are usually done after the initial diagnosis of follicular lymphoma. Follicular lymphomas usually present with lymphadenopathy but may also have involvement of spleen, bone marrow and other sites of lymphoid tissue. Usually following a tissue diagnosis of follicular lymphoma, imaging studies and a bone marrow biopsy are performed to look for extent of disease involvement. A majority of patients will have extensive disease involvement at the time of diagnosis.

The prognosis of patients with follicular lymphoma is related to the extent of disease at the time of clinical staging and the pathology grade. Grades 1-2 with follicular lymphomas are considered indolent, but not curable lymphomas. Grade 3 lymphomas have a more aggressive clinical course, and usually any follicular lymphoma with a complement of diffuse large B cell areas are regarded as diffuse large B cell lymphomas and treated as such. Any rapidly enlarging lymph nodes or masses in a patient with follicular lymphoma are an indication for a biopsy of that rapidly growing tissue to look for transformation to a diffuse large B cell lymphoma.

What Tests Should I Request to Confirm My Clinical Dx? In addition, what follow-up tests might be useful?

because Because follicular lymphomas form follicles, it is important to distinguish a reactive follicular hyperplasia (a benign reactive process) from follicular lymphoma. Occasionally, the morphology is ambiguous and both flow cytometry and/or immunohistochemistry studies may be helpful. Other lymphomas that may be in the differential diagnosis when there is a nodular pattern include small lymphocytic lymphoma (or chronic lymphocytic leukemia) and mantle cell lymphoma. However, both small lymphocytic lymphoma/chronic lymphocytic leukemia and Mantle cell lymphoma are characterized by CD5 positive B cells (follicular lymphomas have CD10 positive B cells).