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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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Organ Systems, Breast

Special Subtypes of Breast Carcinoma

  • Lobular Carcinoma
  • Medullary Carcinoma
    • Pattern characteristic of BRCA1 associated carcinomas
      • 13% are medullary type
      • 60% have subset of medullary features
    • Well-circumscribed mass
      • Solid sheets of pleomorphic large cells containing prominent nucleoli In >75% of the mass
      • Frequent mitosis
      • Prominent lymphoplasmacytic inflammatory infiltrate surrounding and infiltrating the tumor
      • Pushing/non-infiltrating border
      • DCIS is minimal or absent
    • WHO recommends classifying tumor as “carcinomas with medullary features”
  • Micropapillary Carcinoma
  • Mucinous (colloid) carcinoma
  • Tubular Carcinoma
  • Papillary Carcinoma
  • Secretory Carcinoma
  • Inflammatory Carcinoma
    • Clinically present with breast erythema and thickening (peau d’orange)
    • Dermal lymphatics filled with tumor
    • 3-year survival rate 3-10%
  • Neuroendocrine Tumors
    • Well-differentiated Neuroendocrine Tumor
    • Small Cell Carcinoma
References

Kumar, Vinay, Abul K. Abbas, and Jon C. Aster. Robbins and Cotran Pathologic Basis of Disease. Ninth edition. Philadelphia, PA: Elsevier/Saunders, 2015.