Follicular hyperplasia

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Author: Mikael Häggström [notes 1]
Follicular hyperplasia is the most common pattern of reactive lymphadenopathy.[1] Reactive follicular hyperplasia is usually associated with varying degrees of paracortical and/or sinus hyperplasia. Older age, increased follicular density (especially back-to-back arrangement) and areas of diffuse nodal effacement leads to a suspicion of follicular lymphoma.[1]

Main differences:[1]

Feature Reactive follicular hyperplasia Follicular lymphoma
Density of follicles Low High
Follicle distribution Usually limited to subcortical region Distributed evenly throughout parenchyma
Follicles extending beyond capsule Rarely Often
Follicle sizes and shapes Uneven Similar
Cell types in germinal centers Mixture of cells Monomorphic or polymorphic
Tingible-body macrophages Present Usually rare
Mitotic rate Usually moderate to high Usually low to moderate
Mantle zone Usually distinct Usually indistinct or absent
Cell polarization Often seen Usually absent
Interfollicular areas Large Compressed
Areas of nodal effacement Absent Occasional

If uncertain, perform the following studies:[1]

Feature Reactive follicular hyperplasia Follicular lymphoma
Bcl-2 in B cells of germinal centers Negative Positive (90%)
Light chain restriction on immunostains Absent (rare exceptions) Present (20% in paraffin)
Light chain restriction on flow cytometry Absent restriction (rare exceptions) Restriction or absent, when gated correctly (95%)
Ig rearrangements Absent (rare exceptions) Usually (80%)
t(14;18) Absent (rare exceptions) Usually present (90%)

Notes

  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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References

  1. 1.0 1.1 1.2 1.3 Weiss, Lawrence M; O'Malley, Dennis (2013). "Benign lymphadenopathies ". Modern Pathology 26 (S1): S88–S96. doi:10.1038/modpathol.2012.176. ISSN 0893-3952.