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'''Follicular lymphoma''', abbreviated '''FL''', is a very common non-Hodgkin lymphoma. It is a [[small cell lymphoma]] and usually has an indolent behaviour. | |||
==General== | |||
*A very common type of lymphoma. | |||
*Expresses BCL2,<ref name=pmid18359244>{{cite journal |author=Vitolo U, Ferreri AJ, Montoto S |title=Follicular lymphomas |journal=Crit. Rev. Oncol. Hematol. |volume=66 |issue=3 |pages=248–61 |year=2008 |month=June |pmid=18359244 |doi=10.1016/j.critrevonc.2008.01.014 |url=}}</ref> like many other small cell lymphomas. | |||
==Microscopic== | |||
Features (lymph node): | |||
*Abundant abnormally-shaped lymphoid follicles - '''key feature''' - including some of the following: | |||
**Non-polarized mantle zone (normal mantle zone is usu. thicker at capsular aspect). | |||
**Non-polarized germinal center (normal germinal center has dark & light area). | |||
**Loss of tingible body macrophages. | |||
**Sinuses effaced (lost). | |||
Note: | |||
*The intrafollicular component of the lymph node is compressed - follicles are often described as "kissing", as they nearly touch. | |||
*In [[bone marrow]] specimens the neoplastic cells classically have a paratrabecular arrangement,<ref name=pmid17284114>{{Cite journal | last1 = Iancu | first1 = D. | last2 = Hao | first2 = S. | last3 = Lin | first3 = P. | last4 = Anderson | first4 = SK. | last5 = Jorgensen | first5 = JL. | last6 = McLaughlin | first6 = P. | last7 = Medeiros | first7 = LJ. | title = Follicular lymphoma in staging bone marrow specimens: correlation of histologic findings with the results of flow cytometry immunophenotypic analysis. | journal = Arch Pathol Lab Med | volume = 131 | issue = 2 | pages = 282-7 | month = Feb | year = 2007 | doi = 10.1043/1543-2165(2007)131[282:FLISBM]2.0.CO;2 | PMID = 17284114 }}</ref> i.e. the lymphoma cells are found adjacent to the bone spicules. | |||
DDx: | |||
*Reactive follicular hyperplasia. | |||
*[[Diffuse large B-cell lymphoma]] - esp. for the grade 3B. | |||
===Images=== | |||
*[http://www.flickr.com/photos/euthman/3311641845/ Follicular lymphoma - bone marrow (flickr.com)]. | |||
*[http://library.med.utah.edu/WebPath/HEMEHTML/HEME034.html Follicular lymphoma (utah.edu)]. | |||
===Grading=== | |||
*Grade 1-2: <= 22 centroblasts / HPF; where 1 HPF ~= 0.2376 mm^2 (22 mm eye piece @ 40X objective). | |||
*Grade 3A: >22 centroblasts / HPF; where 1 HPF ~= 0.2376 mm^2 (22 mm eye piece @ 40X objective). | |||
*Grade 3B: only centroblasts (within a nodular architecture). | |||
Notes: | |||
*Significant interobserver variability.<ref>DG. 17 August 2010.</ref> | |||
*Grade 1 & Grade 2 lumped together. | |||
*One should evaluate 10 HPFs. | |||
*''Only'' centroblasts ''without'' a nodular architecture is ''[[Diffuse large B cell lymphoma]]'' ([[DLBCL]]). | |||
The usual cut points mentioned by people with [[HPFitis]] are:<ref name=Ref_Sternberg4_813>{{Ref Sternberg4|813}}</ref> | |||
*Grade 1: 0-5 centroblasts / HPF. | |||
*Grade 2: 5-15 centroblasts / HPF. | |||
*Grade 3: >15 centroblasts / HPF. | |||
==IHC== | |||
Features:<ref name=pmid18359244/> | |||
*CD10 +ve. | |||
*BCL6 +ve. | |||
Others: | |||
*CD5 -ve. | |||
**+ve in mantle cell lymphoma. | |||
*CD23 -ve/+ve. | |||
**+ve in CLL. | |||
*CD43 -ve. | |||
**+ve in mantle cell lymphoma, marginal zone lymphoma. | |||
*CD11c -ve -- flow cytometry only. | |||
*CD21 -ve in tumour cells; highlights follicular dendritic cells. | |||
Image: | |||
*[http://www.pathpedia.com/education/eatlas/histopathology/lymph_node/follicular_lymphoma/follicular-lymphoma-%5B16-ln021_cd21%5D.jpeg Follicular lymphoma - CD21 (pathpedia.com)]. | |||
A panel to work-up: | |||
*BCL2, BCL6, CD3, CD5, CD10, CD20, CD23, cyclin D1. | |||
==Molecular== | |||
*t(14;18)(q32;q21)/IGH-BCL2 in 70-95% of cases.<ref name=pmid18359244/> | |||
**Should not be confused with t(14;18)(q32;q21)/IGH-MALT1 seen in MALT lymphomas.<ref name=pmid16950858>{{cite journal |author=Bacon CM, Du MQ, Dogan A |title=Mucosa-associated lymphoid tissue (MALT) lymphoma: a practical guide for pathologists |journal=J. Clin. Pathol. |volume=60 |issue=4 |pages=361–72 |year=2007 |month=April |pmid=16950858 |pmc=2001121 |doi=10.1136/jcp.2005.031146 |url=}}</ref> | |||
==Sign out== | |||
<pre> | |||
RETROPERITONEAL MASS, RIGHT, CORE BIOPSIES: | |||
- NON-HODGKIN B-CELL LYMPHOMA, FAVOUR FOLLICULAR LYMPHOMA. | |||
COMMENT: | |||
Morphology: | |||
-Small cells: size ~ mature lymphocytes, quantity - many, angular and round. | |||
-Large cells (intermixed with small cells): size ~1.5-2x mature lymphocyte, | |||
small nucleoli, moderate quantity of grey/basophilic cytoplasm, moderate | |||
nuclear pleomorphism. | |||
-Architecture: no gland formation, discohesive, no follicles apparent, no sheets | |||
of large cells. | |||
-Mitoses are uncommon. | |||
Immunohistochemical stains (tumour cells): | |||
Positive: CD45 (strong, membranous/cytoplasmic), CD20 (strong, membranous/cytoplasmic), | |||
BCL-2 (strong, membranous/cytoplasmic), CD10 (strong, membranous), BCL-6 (moderate, | |||
patchy, nuclear). | |||
Negative: pankeratin, CD3, CD5, CD30, CD21 (follicular dendritic cells not apparent), | |||
CD23 (scattered, rare). | |||
Ki-67: highlights the large cells, primarily -- 5-35% of cells within the core. | |||
The findings favour a follicular lymphoma, based on the cellular morphology and | |||
immunostains; however, they are limited by the type of tissue sampling (core biopsy). | |||
Clinical correlation is suggested. | |||
</pre> | |||
==See also== | |||
*[[Small cell lymphomas]]. | |||
*[[Lymphoma]]. | |||
*[[Lymph node pathology]]. | |||
==References== | |||
{{Reflist|2}} | |||
[[Category:Diagnosis]] | [[Category:Diagnosis]] | ||
[[Category:Small cell lymphomas]] | |||