Leukemias
Etiology of Leukemias
General outlines
Acute leukemias
Single cell mutation with “freezing” farther cell’s differentiation and
maturation in early stages of development (e.g. stem cell)
Chronic leukemias
The abnormal mutated (or transformed) cells will retain some capabilities to
maturate (and differentiate) beyond the early cells (blasts) BUT they are all
abnormal and useless malignant cells.
A systematic approach to diagnose different hematologic
neoplasms:
1) CBC (Complete Blood Count), CBP (Complete Blood Picture)
a) WBC total, differential count, left shift?,
b) Peripheral blood film: evaluate the cellular constituents and search for abnormalities (abnormal cells?).
2) Special staining (SBB, MPO, NSE, etc).
3) Bone marrow aspiration:
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assess the cellularity
M:E ratio
percentage of blast cells
The maturation and differentiation of various cell lineage (Lymphoid, Myeloid).
4) Bone marrow biopsy (trephine biopsy):
► in solid tumors (as lymphomas with invasion to Bone marrow)
► in cases that Bone marrow aspiration not possible (AML-M7 “due to fibrosis”, Hairy cell Leukemias, etc)
► in cases with a compact bone marrow “very high cellular proliferation and a dry tap”
5) Immunophenotyping:
Use of cell surface, cytoplasmic, or nuclear markers to define cell’s character and origin (phenotyping) BY
Flow cytometry and Immunohistochemistry studies.
6) Genetics studies
► Cytogenetics findings
► Molecular genetics studies
Leukemia classification
►1976
French, American and British hematologists (FAB group) proposed
a classification system (FAB classification):
a) Morphologic assessment
b) Special staining techniques (if required)
c) Limited use of Monoclonal antibodies (in selected cases)
► 2001
WHO classification of Hematopoietic and Lymphoid malignancies.
i) Adopting the FAB morphologic classification.
ii) Limited use of special staining techniques.
iii) Wider use of immunophenotyping (cell markers) studies (FC, IHC)
iv) Cytogentics and Molecular genetics studies used heavily to define
v) The character and prognosis of various disease entities.
► 2008
An Updated WHO classification has been edited.
Differences between FAB and WHO
FAB-classification:
1) Heavily used “Morphologic Findings”
2) Special staining (SBB, MPO, NSE, etc), if required
WHO-classification:
1) Morphologic findings
2) Special staining (decreased role)
3) Immunophenotyping (in the form of FC and IHC) heavily used.
4) Cytogentics and Molecular genetics studies frequently used.
Leukemias
Acute leukemias
Lymphoid
L1
L2
L3
Chronic leukemias
Myeloid
M0
M1
M2
M3
M4
M5
M6
M7
The original FAB-Classification system of Acute Leukemias,
heavily based on morphologic findings
L1
Myeloblast type I
L2
L3
Myeloblast type II
Types of blast cells in ALL and AML
Special staining methods in acute leukemias
FAB-classification of ALL
ALL-L1
ALL-L2
ALL-L3
L1-lymphoblasts in the BM
L2-lymphobalsts in the BM
L3-lymphoblasts in the BM
SBB
MPO
(SHOULD BE –ve)
(SHOULD BE –ve)
FAB-classification of AML
M0 Undifferentiated blast cells (Myeloid origin by immunophenotyping),
Special staining SBB-ve, MPO-ve
M1 Myeloblasts (≥ 20% in BM) SBB+ve, MPO+ve
M2 Myeloblasts (≥20% in BM) SBB+ve, MPO+ve
M3 Abnormal Promyelocytes SBB+ve, MPO+ve
M4 Myeloblasts (20-80%) + Monocytes (>20%), NSE +ve
M5 (a): Monoblasts ≥80% NSE +ve
(b): Monoblasts <80%, more promonocytes and monocytes in BM,NSE +ve
M6 Erythroleukemia, 50% of BM cells are of erythroid lineage
M7 Blast cells are ≥20% of BM cells (they are identifiable as Megakaryoblasts).
2 important Practical points:
BM aspiration results in acute leukemia, although may be:
i) dry tap or
ii) difficult to aspirate (hypercellular marrow with excessive marrow blasts)
BUT is never ever an empty marrow.
Leukemoid reaction should be distinguished from Leukemias “of particular CML”
a)
b)
c)
d)
Neutrophil Alkaline Phosphatase Score
C-reactive protein, ESR, and other inflammatory indicators.
Blood film finding (left shift).
Bone marrow aspiration, Bone marrow biopsy, immunophenotyping
and cytogentics studies may required accordingly.
The Current WHO classification has widely used the
immunophenotyping to characterize leukemias and lymphomas
Frequently used Immunophenotyping & Genetics studies
The Panel of Antibodies recommended by the British Committee for Standards in
Haematology (BCSH) for the Diagnosis and classification of acute leukemia are as
follows:
T-Lymphoid markers:
B-Lymphoid markers:
CD19
CD22 (cytoplasmic)
CD79a (cytoplasmic)
CD10
Cytoplasmic µ
Surface membrane Ig
CD138
CD3 (cytoplasmic)
CD2
CD7
Non-lineage restricted:
TdT
CD45
HLA-DR
Myeloid markers:
CD13
CD117
anti-MPO (cytoplasmic)
CD33
CD41
CD42
CD61
anti-Glycophorin A
Immunological subtypes of Acute Leukemia
►B-ALL (B-lineage markers are positive), ≈75% of ALL
1) pro B-ALL
2) common ALL (CD19+/CD10+/TdT+/CD34+/-)…THE MOST COMMON
3) B-ALL (the most mature) (CD34-ve/cytoplasmic and surface Ig positive)
►T-ALL (T-lineage markers are positive), ≈15% of ALL
►AML (Myeloid lineage markers (CD13/CD33, CD117, cyMPO) are positive
►Bi-lineage
►Bi-Phenotypic
Cytogenetics/molecular genetics findings in ALL (as example)
ONLY FOR YOUR REVIEW
ALL-L1
Small and homogenous blasts. These may closely resemble
lymphocytes but are distinguished by their finer chromatin structure and
the occasional presence of nucleoli
ALL-L2
Lymphoblasts of varying size (small and large)
Large blast cells with marked cytoplasmic budding (blebing).
The differential diagnosis will be: AML-M7 and ALL.
Farther cytochemical and immunophenotyping studies
showed to be case of B-lineage ALL.
Mature B-ALL with prominent cytoplasmic vacuoles
Auer rods in AML (pathogmonomic for myeloid lineage origin),
A case of AML-M3
Auer rods in malignant promyelocytes
Auer rods in an M1/M2 AML
Thank You