- >20% clonal plasma cells in the peripheral blood (PB)
- (or) >2,000/μL absolute count in PB
Category Archives: Hematopathology
Plasmacytoma
2016 WHO Classification
- Solitary Plasmacytoma of Bone
- Extra-osseous Plasmacytoma
B-PLL
B-Cell Prolymphocytic Leukemia
A rare mature B-cell leukemia (~1% of cases) composed of medium sized lymphoid cells (2x size of normal lymphocyte), which typically has splenic and bone marrow involvement.
Plasma Cell Neoplasms
2016 WHO Classification
- Monoclonal Gammopathy (MGUS) – IgM
- Monoclonal Gammopathy (MGUS) – Non-IgM
- Plasma Cell Myeloma
- Plasma Cell Myeloma – Variants
- Smoldering Plasma Cell Myeloma (Asymptomatic)
- Non-Secretory Myeloma
- Plasma Cell Leukemia
- Plasmacytoma
- Solitary Plasmacytoma of Bone
- Extraosseous Plasmacytoma
- Monoclonal Immunoglobulin Deposition Disease
Large B-Cell Lymphomas
- Diffuse Large B-Cell Lymphoma (DLBCL), NOS
- Germinal Center B-Cell Type
- Activated B-Cell Type
- Large B-Cell Lymphoma with IRF4 Rearrangement
- T-Cell/Histiocyte-Rich Large B-Cell Lymphoma
- Primary DLBCL of the CNS
- Primary Cutaneous DLBCL, Leg Type
- EBV+ DLBCL, NOS
- DLBCL Associated with Chronic Inflammation
- Primary Mediastinal (Thymic) Large B-Cell Lymphoma
- Intravascular Large B-Cell Lymphoma
- ALK+ Large B-Cell Lymphoma
- Plasmablastic Lymphoma
- HHV-8+ DLBCL, NOS
- Primary Effusion Lymphoma
WHO 2008/2016 Criteria for Mixed-Phenotype Blasts
Myeloid
- MPO expression (flow cytometry, immunohistochemistry, or enzyme cytochemistry) – WHO does not define thresholds for positiivity, which can result in variability between laboratories
- Flow cytometry: >10% (some propose 13%) expression compared to isotype control (preferred methodology)
- Enzyme cytochemsitry: >3% staining of blasts
- IHC: No well-defined cutoff (not commonly done – MPO IHC is available)
Continue reading WHO 2008/2016 Criteria for Mixed-Phenotype Blasts
EGIL Algorithm for Biphenotypic Blasts
European Group for the Immunological Characterization of Leukemias (EGIL) algorithm for biphenotypic blasts.
|
Points
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B
|
T
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Myeloid
|
|
2
|
cyCD79a
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CD3 (cy or sm)
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MPO
|
|
|
cyCD22
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TCR-αβ
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|
|
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cyIgM
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TCR-γδ
|
|
|
1
|
CD19
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CD2
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CD117
|
|
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CD20
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CD5
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CD13
|
|
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CD10
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CD8
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CD33
|
|
|
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CD10
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CDw65
|
|
0.5
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TdT
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TdT
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CD14
|
|
|
CD24
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CD7
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CD15
|
|
|
|
CD1a
|
CD64
|
Biphenotypic leukemia is defined as a score >2 in 2 lineage columns.
WHO 2008/2016 Criteria for Mixed-Phenotype Blasts
Mixed Phenotypic Acute Leukemias (MPAL)
References
Bene MC, Castoldi G, Knapp W, et al. Proposals for the immunological classification of acute leukemias: European Group for the Immunological Characterization of Leukemias (EGIL). Leukemia. 1995;9(10):1783–1786
MPAL
Mixed Phenotype Acute Leukemia (MPAL) comprises either blasts with myeloid and lymphoid expression or leukemia with a mixture of myeloblasts and lymphoblasts.
- BIPHENOTYPIC – single population of blasts that express key markers of different lineages (e.g. T-ALL, B-ALL, and/or AML).
- BILINEAL – two cell populations each diagnostic of separate acute leukemia lineages (combined populations ≥20% blasts to met threshold for acute leukemia).