Extranodal Marginal Zone B Cell Lymphoma
Differential Diagnosis
- Extranodal vs. Nodal vs. Splenic marginal zone lymphomas
- Immunologic differences of small B cell lymphomas
- SLL / CLL
- Lymphoplasmacytoid lymphoma / Immunocytoma
- Mantle cell Lymphoma
- Follicular lymphoma
- Mast cell disease
- Marginal zone hyperplasia
- Diffuse large B cell lymphoma vs.marginal zone lymphoma with transformation
- Plasmacytoma
- Enteropathy type T cell lymphoma
Extranodal vs. Nodal vs. Splenic Marginal Zone Lymphomas
- Extranodal involvement takes precedence in separation of the three types
- Mixed types are designated as extranodal with nodal or splenic involvement
- Nodal type must lack extranodal involvement
- Splenic type must lack both extranodal and peripheral nodal involvement
- Splenic hilar nodes may be involved
- Genetic abnormalities are incompletely studied but support the above separation
| Extranodal | Nodal | Splenic | |
|---|---|---|---|
| 7q21-32 loss | rare | rare | 40% |
| trisomy 3 | 60% | rare | 17% |
| t(11;18) | 25-50% | rare | 0% |
Small B Cell Lymphomas
| 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
| Extranodal Marginal Zone Lymphoma | SLL/CLL |
|---|---|
| Nodular pattern with prominent marginal zone | Diffuse effacement |
| Polymorphous cell population | Uniform small round lymphocytes |
| May have residual germinal centers | Proliferation centers frequent |
| CD23 8% | CD23 85% |
| CD5 negative | CD5 80% |
| CD43 35% | CD43 80% |
| Nodal, Extranodal and Splenic Marginal Zone Lymphoma | Lymphoplasmacytic Lymphoma |
|---|---|
| Enlarged marginal zone | Diffuse effacement |
| Pale monocytoid cells | No monocytoid population |
- No useful distinguishing immunologic markers
- Marginal zone lymphomas are frequently plasmacytoid; this combined with the lack of a definitive marker can make this distinction difficult
- The distinction is sometimes suggested by the propensity to involve mucosal sites by extranodal marginal zone lymphoma
| Nodal, Extranodal and Splenic Marginal Zone Lymphoma | Mantle Cell Lymphoma |
|---|---|
| Enlarged marginal and mantle zones | Enlarged mantle zone frequent |
| Polymorphous population | Uniform small lymphocytes |
| bcl1 negative | bcl1 85% |
| CD25 negative | CD25 30% |
| CD5 negative | CD5 80% |
| CD43 35% (Splenic 2%) | CD43 85% |
- Both may involve the GI tract and other mucosal sites in extranodal cases.
- Enlarged marginal and mantle zones may be hard to distinguish
| 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
| Nodal, Extranodal and Splenic Marginal Zone Lymphoma | Mast Cell Disease |
|---|---|
| B lineage markers positive | B lineage markers negative |
| Toluidine blue, Giemsa stains negative | Toluidine blue, Giemsa stains positive |
| CD117, tryptase immuno stains negative | CD117, tryptase immuno stains positive |
| Nodal, Extranodal and Splenic Marginal Zone Lymphoma | Marginal Zone Hyperplasia |
|---|---|
| Monocytoid cells may be prominent | No monocytoid population |
| Light chain monotypia variably demonstrable | No monotypia |
| Clonal Ig gene rearrangement | No clonal rearrangement |
| Coexpression of CD43 by B cells 35% | No CD43 coexpression |
| Sheets of B cells | Distinct B and T cell zones |
| Nodal, Extranodal and Splenic Marginal Zone Lymphoma with Large Cell Transformation | Sporadic Diffuse Large B Cell Lymphoma |
|---|---|
| Prior or concurrent specimen with typical marginal zone lymphoma | No evidence of typical marginal zone lymphoma |
| CD5 negative | CD5 10% |
| CD10 2% | CD10 25-50% |
| bcl6 negative | bcl6 60% |
| Plasmacytoma / Myeloma | Lymphoplasmacytic Lymphoma and Nodal, Extranodal and Splenic Marginal Zone Lymphomas |
|---|---|
| Plasma cells may be pleomorphic or plasmablastic | Plasma cell component usually not markedly atypical |
| Uniform plasma cell morphology | Plasma cells mixed with small lymphocytes |
| IgG or IgA M component most common | IgM or IgG M component most common |
| CD20 often negative | CD20 80% |
| Uniformly CD138 positive | Scattered CD138 positive cells |
| Often CD56+, CD19-, CD45- | CD56-, CD19+, CD45+ |
| Extranodal Marginal Zone Lymphoma | Enteropathy Type T Cell Lymphoma |
|---|---|
| Generally predominantly small cell pattern | Wide variety of patterns |
| B lineage | T lineage |
