From Libre Pathology
|Diagnosis in short|
Follicular lymphoma. H&E stain.
|LM||Lymph node: abundant abnormally-shaped lymphoid follicles with some of the following: non-polarized mantle zone, non-polarized germinal center, loss of tingible body macrophages, sinuses effaced (lost)|
|LM DDx||diffuse large B-cell lymphoma, other small cell lymphomas, reactive follicular hyperplasia|
|IHC||CD20 +ve, CD10 +ve, BCL-6 +ve, BCL-2 +ve|
|Molecular||t(14;18)(q32;q21) / IGH-BCL2|
|Gross||white lesions +/-subtle fine nodularity (fish flesh-like appearance)|
|Site||lymph node, spleen, bone marrow, others|
|Prognosis||moderate to good|
|Clin. DDx||other causes of lymphadenopathy - other lymphomas, metastatic carcinoma|
- A very common type of lymphoma.
- Moderate prognosis - overall five year survival ~ 66% in one cohort without transformation.
- May transform to a more aggressive lymphoma, e.g. diffuse large B-cell lymphoma.
- Lymph node enlargement.
- Classically white and uniform - usually described as fish flesh-like.
- May have a vague nodularity.
FL in the spleen. (WC)
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).
- 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, i.e. the lymphoma cells are found adjacent to the bone spicules.
- Reactive follicular hyperplasia.
- Diffuse large B-cell lymphoma - esp. for the grade 3B.
- 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).
- Significant interobserver variability.
- Grade 1 & Grade 2 lumped together.
- One should evaluate 10 HPFs.
- Only centroblasts without a nodular architecture is Diffuse large B cell lymphoma (DLBCL).
- Grade 1: 0-5 centroblasts / HPF.
- Grade 2: 5-15 centroblasts / HPF.
- Grade 3: >15 centroblasts / HPF.
- CD10 +ve.
- BCL6 +ve.
- 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.
- BCL2 +ve - like many other small cell lymphomas.
- Usually negative in benign germinal centres.
A panel to work-up:
- BCL2, BCL6, CD3, CD5, CD10, CD20, CD23, cyclin D1.
- t(14;18)(q32;q21)/IGH-BCL2 in 70-95% of cases.
- Should not be confused with t(14;18)(q32;q21)/IGH-MALT1 seen in MALT lymphomas.
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.
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