Follicular lymphoma

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Author: Mikael Häggström [note 1]
In suspected follicular lymphoma:


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  • Minimal depth
  • (Moderate depth)
  • ((Comprehensive))

Microscopic evaluation

Usual follicular lymphoma has at least partial follicular (nodular) distribution.[1]

Differential diagnosis

  • Follicular hyperplasia, also having prominent follicular centers. Compared to follicular lymphoma, it is more prevalent at younger age, has lower follicular density (typically not having back-to-back arrangement) and not typically having diffuse nodal effacement.[2] Further information: Follicular hyperplasia


Histologic comparison of cell types in a germinal center, H&E stain:
- Centrocytes are small to medium size with angulated, elongated, cleaved, or twisted nuclei.
- Centroblasts are larger cells containing vesicular nuclei with one to three basophilic nucleoli apposing the nuclear membrane.
- Follicular dendritic cells have round nuclei, centrally located nucleoli, bland and dispersed chromatin, and flattening of adjacent nuclear membrane.

Follicular lymphoma is graded as follows:[3]

  • Grade 1: follicles have <5 centroblasts per high-power field (HPF). At least 8 HPFs (1.6 mm2) should be counted. Further information: Count per area unit
  • Grade 2: follicles have 6 to 15 centroblasts per HPF.
  • Grade 3: follicles have >15 centroblasts per HPF.
    • Grade 3A: Grade 3 in which the follicles contain predominantly centrocytes.
    • Grade 3B: Grade 3 in which the follicles consist almost entirely of centroblasts.


The following panel of immunohistochemitry is recommended for confirmation and evaluation of follicular lymphoma:[4]

  • Suspected follicular lymphoma, grades 1 to 3a: CD10, CD20, CD21, BCL2, and cyclin D1
  • Suspected follicular lymphoma, grade 3b: CD20, CD21, BCL2, BCL6, cyclin D1 and MUM1 (same as above but without CD10 and addition of BCL6 and MUM1)

(Describe the pattern of CD21 staining of follicular dendritic cells, generally conforming to one of the following:[5])

Distribution patterns of CD21 (also applicable to CD23) of dendritic cells.[5]

Microscopic report


Lymph node, excision:
Follicular lymphoma

Comment: Sections show lymph nodal architecture which is effaced by a neoplastic nodular proliferation of predominantly small cleaved lymphoid cells (centrocytes). These cells and the interfollicular lymphocytes are positive for CD20, CD79a and Bcl-2, while the germinal center cells are also positive for CD10 and Bcl-6. There is no increase in large cells (centroblasts). These changes are consistent with a low-grade (WHO 1-2 out of 3) follicular lymphoma.


  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.

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  1. Mahsa Khanlari, M.D., Jennifer Chapman, M.D.. Lymphoma & related disorders - Mature B cell neoplasms - Follicular lymphoma - Follicular-usual. Topic Completed: 26 February 2020. Minor changes: 16 June 2021
  2. Weiss, Lawrence M; O'Malley, Dennis (2013). "Benign lymphadenopathies ". Modern Pathology 26 (S1): S88–S96. doi:10.1038/modpathol.2012.176. ISSN 0893-3952. 
  3. Weissmann, David. Follicular Lymphomas. University of Medicine and Dentistry of New Jersey.
  4. Disanto MG, Ambrosio MR, Rocca BJ, Ibrahim HA, Leoncini L, Naresh KN (2016). "Optimal Minimal Panels of Immunohistochemistry for Diagnosis of B-Cell Lymphoma for Application in Countries With Limited Resources and for Triaging Cases Before Referral to Specialist Centers. ". Am J Clin Pathol 145 (5): 687-95. doi:10.1093/ajcp/aqw060. PMID 27247372. Archived from the original. . 
  5. 5.0 5.1 Kurshumliu F, Sadiku-Zehri F, Qerimi A, Vela Z, Jashari F, Bytyci S (2019). "Divergent immunohistochemical expression of CD21 and CD23 by follicular dendritic cells with increasing grade of follicular lymphoma. ". World J Surg Oncol 17 (1): 115. doi:10.1186/s12957-019-1659-8. PMID 31269981. PMC: 6610797. Archived from the original. . 
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