Follicular Lymphoma
Differential Diagnosis
- Immunologic differences of small B lymphomas
- Reactive follicular hyperplasia
- Castleman disease, hyaline vascular type
- Progressive transformation of germinal centers
- Nodular lymphocyte predominant Hodgkin lymphoma
- Mantle cell lymphoma
- Marginal zone lymphoma
- SLL/CLL with pseudofollicular proliferation centers
SLL/CLL | Mantle | Marginal Zone | Lymphoplasmacytic | Follicular | |
---|---|---|---|---|---|
CD23 | 85% | 2% | 8% | 0-30% on immunohistology but up to 60% weak positive on flow | 0-25% |
CD5 | 80% | 80% | 0% | 5% | 0% |
bcl1 | 2% | 85% | 0% | 0% | 0% |
CD10 | 0% | 2% | 2% | 3% | 85% |
CD43 | 80% | 85% | 35% | 10-30% | 7% |
bcl2 | 95% | 95% | 65-90% | >50% | 90% |
- CD23 staining refers to lymphoid staining
- Follicular dendritic cells stain in many processes
- bcl1
- Blastic mantle cell lymphoma 100%
- Hairy cell leukemia 41%
- CD43 stains only 2% of splenic marginal zone lymphoma
Reactive Follicular Hyperplasia | Follicular Lymphoma |
---|---|
Follicles not densely packed (30/40x field) | Follicles densely packed (47/40x field) |
Normal architecture retained | Obliterates normal architecture |
Variable size and shape of follicles | Uniform size and shape of follicles |
Well defined mantles | Poorly defined mantles |
Extracapsular follicles infrequent | Extracapsular follicles may be seen |
Many tingible body macrophages | Infrequent tingible body macrophages |
Mixed population in follicles | Uniform population of atypical cells |
Interfollicular cells bland | Interfollicular cells may be small, cleaved |
bcl2 negative in follicles | bcl2 positive in follicles (100% in grade 1) |
Light chains mixed (variably demonstrable in paraffin) | Light chains monotypic (variably demonstrable in paraffin) |
Germ line Ig genes | Ig gene rearrangement |
Castleman disease | Follicular Lymphoma |
---|---|
Numerous small depleted follicles | Cellular follicles |
Prominent mantles with concentric layering | Mantles generally indistinct |
Penetrating hyalinized vessels | Penetrating vessels rare |
Progressive Transformation of Germinal Centers | Follicular Lymphoma |
---|---|
Small number of large atypical nodules | Many atypical small nodules |
Surrounding typical reactive follicles | Surrounding reactive follicles unusual |
Nodules predominantly composed of small non-atypical lymphocytes | Nodules composed of atypical lymphocytes |
Nodular Lymphocyte Predominant Hodgkin Lymphoma | Follicular Lymphoma |
---|---|
Limited number of large nodules | Innumerable small nodules |
Scattered large cells in background of normal small cells | Nearly all cells atypical, small or large |
EMA positive large cells (variably) | EMA negative |
Light chain polytypia or negative | Light chain monotypia or negative |
CD57+ cells increased, with ringing around large cells | No CD57 increase |
Follicular Lymphoma | Mantle Cell Lymphoma |
---|---|
Distinct nodules composed of cleaved cells | Residual germinal centers may simulate nodules |
Mantle pattern surrounding germinal center rare | Mantle pattern frequent |
bcl1 negative | bcl1 85% |
CD5 negative | CD5 80% |
CD43 7% | CD43 85% |
CD10 85% | CD10 2% |
Follicular dendritic network intact | FDC network disrupted or confined to germinal centers |
bcl2 92% | bcl2 95% |
Extranodal Marginal Zone Lymphoma | Follicular Lymphoma |
---|---|
Polymorphous population | Uniform population of atypical small lymphocytes |
Centers of nodules may contain bcl2 negative residual germinal centers | Centers of nodules composed of bcl2 positive small atypical lymphocytes |
Plasmacytoid differentiation frequent | Plasmacytoid differentiation rare |
Lymphoepithelial lesions may be seen | No lymphoepitelial lesions |
CD10 2% | CD10 85% |
- Both may involve the GI tract and other mucosal sites
- Both usually express bcl2 in the neoplastic cells
- Cases with combined features are occasionally seen
Follicular Lymphoma | SLL/CLL |
---|---|
Distinct nodular pattern | Vague proliferation centers |
Nodules composed of cleaved cells | Nodules composed of prolymphocytes and paraimmunoblasts |
Interfollicular cleaved cells common | Background sheets of regular small lymphocytes |
CD23 0-38% | CD23 85% |
CD5 negative | CD5 80% |
CD43 7% | CD43 80% |
CD10 85% | CD10 0% |