Category Archives: Bone Marrow

Organ Systems, Bone Marrow, Multiple Myeloma, WHO Classification, Hematopathology

Smoldering (Asymptomatic) Myeloma 

Smoldering (Asymptomatic) Myeloma 
  • >3 gm/dL serum M protein (or) urinary M protein ≥500 mg/24 hours
  • (and/or) 10-60% bone marrow plasma cells (usually 10-20% plasma cells)
  • Asymptomatic patients with no evidence of end-organ damage or biomarker evidence of malignancy (myeloma-defining events)

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Organ Systems, Bone Marrow, Multiple Myeloma, Lymph Node, WHO Classification, Hematopathology

Plasma Cell Neoplasms

2016 WHO Classification

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Organ Systems, Bone Marrow, Lymph Node, WHO Classification, Hematopathology

Large B-Cell Lymphomas

Organ Systems, WHO Classification, Hematopathology, Acute Leukemia

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)

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Organ Systems, Bone Marrow, WHO Classification, Hematopathology, Acute Leukemia

EGIL Algorithm for Biphenotypic Blasts

European Group for the Immunological Characterization of Leukemias (EGIL) algorithm for biphenotypic blasts. 
Points
B
T
Myeloid
2
cyCD79a
CD3 (cy or sm)
MPO
 
cyCD22
TCR-αβ
 
 
cyIgM
TCR-γδ
 
1
CD19
CD2
CD117
 
CD20
CD5
CD13
 
CD10
CD8
CD33
 
 
CD10
CDw65
0.5
TdT
TdT
CD14
 
CD24
CD7
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

 

 

Organ Systems, Bone Marrow, Hematopathology, Acute Leukemia

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).

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