Origin of WBCs (Blasts) and Leukemia

Origin of WBCs (Blasts)

• All mature WBCs originate from bone marrow.

Myeloid White Blood Cell Synthesis

• Myeloblast (identified by rods) → 

• Promyelocyte (one of biggest cells) → 

• Myelocyte (D-shaped nucleus)
• Mnemonic: MD degree; 
• critical decision step for Neutrophil/Eosinophil/Basophil based on granule color → 

• Metamyelocyte (M-shaped/indented nucleus) → 

• Band/Stab form (deeper indentation, like hair band) → 

• Mature Cell (Neutrophil, Basophil, or Eosinophil).

Regulation of Leucopoiesis

Factors Stimulating

• Colony stimulating factor (CSF) → Filgrastim

• Granulocyte monocyte colony stimulating factor (GM-CSF) → Sargramostim
• Both in Rx of Neutropenia

• Granulocyte colony stimulating factor (GCSF)

• Monocyte colony stimulating factor (MCSF)

• IL 5 → Eosinophils

• IL 3, 4 → Basophils

• Tumor necrosis factor (TNF)

• Rx of neutropenia: CSF, GM-CSF, GCSF

Thrombopoiesis

• Pathway: PHSC → GM-CSF → Thrombocyte → Megakaryocyte → Platelets

Regulation

 

Acute Leukemias

• Definition: Blast count > 20% in bone marrow or peripheral blood

• Ocular → Roths spot

• The most common malignancy in children.

• The most common hematological malignancy in children.

• Most common leukaemia in children ALL
• B-cell ALL>T-cell ALL
• Children like BALLs

• Superior mediastinal syndrome
• More common in adolescent boys
• T- cell ALL.

Clinical features:

• Fever > 1-2 weeks

• Pancytopenia:
• Anemia: Easy fatiguability, Pallor.
• Thrombocytopenia: Bleeding.
• Leukopenia: Fever, recurrent infections.

• Initially non-specific features:
• Anorexia,
• irritability,
• fever.

• Severe bone/ joint pains.

• Organ involvement:
• Lymphadenopathy,
• hepatosplenomegaly,
• testicular involvement,
• CNS involvement,
• Respiratory involvement.

Clinical differentiation between AML and ALL:

Diagnosis:

• Blasts:
• ≥ 20% blasts in peripheral blood or bone marrow examination

• Exception:
• Irrespective of the % of blasts, diagnostic for AML if:
• t (8;21).
• t (15;17).
• inv 16.

• Cytochemistry:
• ALL: PAS+.
• AML: MPO & SBB (SUDAN BLACK B + STAIN).

• Immunophenotyping:
• Blasts (CD 34+).
• Blast cells of myeloid lineage show MPO +
• indicating AML.
• Blast cells of lymphoid lineage:
• B cells show CD 19.
• T cells show CD3+.
• NK cells show CD16+.

Acute Lymphoblastic Leukemia (ALL)

• Vacuolations → seen in
• Burkitt’s Lymphoma
• ALL L3 (Oil red O)

 

• Definition: Lymphoblast count > 20%.

• Common in: Children.

FAB Classification:

• L1:
• Most common, good prognosis in children.

• L2.

• L3:
• Least common, bad prognosis.
• Blasts show cytoplasmic vacuoles.
• Positive for Oil Red O (contain fat).

WHO Classification:

• B-ALL.

• T-ALL:
• Shows tissue infiltration (brain, mediastinum, testis).
• Testis involvement in boys → poor prognosis.
• Overall, T-ALL is worst.

Genetics and Prognosis:

• Favorable prognosis:
• Age 1-9 years.
• WBC <50,000 / mm3.
• Pre B cell ALL.
• Rapid early response to treatment.
• Hyperdiploidy (> 46 chromosomes; > 2n).
• Trisomies of chromosome 4, 7, 10.
• Translocation 12:21.
• Mnemonic:
• ALL (3 alphabets) → number 3 related factors are good (hyperdiploidy >2, trisomies=3, 1+2=3 or 2+1=3 for t(12;21)).

• Unfavorable prognosis:
• Hypodiploidy (< 2n).
• Translocation 9;22 (190 kDa)
• Age <1 year or >10 years.
• WBC >50,000 / mm3.
• TALL → NOTCH Mutation
• Slow early response to treatment.

Treatment:

• Induction: Acute (Anthra) Leukemia (L asp) → Pray to Christ (Vincristine)
• A- Anthracycline.
• L - L-asparaginase.
• V- Vincristine.
• P- Prednisolone.

• CNS Prophylaxis:
• Intrathecal Methotrexate with or without CNS radiation.

• Consolidation/intensification:
• Acute Leukemia → Metha in Cycle
• A- Anthracycline.
• L - L-asparaginase.
• M - Methotrexate.
• C - Cyclophosphamide.

• Maintenance:
• To prevent relapse.
• Methotrexate.
• 6-Mercaptopurine.

Acute Myeloid Leukemia (AML)

• Definition: Myeloblast count > 20%.

• 45 (AML M4, AML M5) years still Single (Monoblast) → Non specific guy (NSE)

• PAS (PAS +ve) → ALL () if study 367 () days

FAB Classification (M0-M7):

• CAE → M1, M2, M4

• PAS → M3, M6, M7

• NSE → M4, M5

• MO → M1, M2

Treatment of AML:

• Drugs used in M3::
• Arsenic
• ATRA (All Trans Retinoic Acid)
• Ara-C (cytosine arabinoside).
• Anthracycline (doxorubicin).
• Avoid chemo

Chronic Leukemias (General)

• CML
• Kamal → Basil → Basophils
• Dont Put on actress on Lap
• PNH & CML → Low Lap
• Goes to College and Garden Parties
• Like FISH → Ph chrom
• He is pseudo → so we will get him - Gotcha!!! (Pseudogaucher)
• GIST & CML → Imatinib

• CLL
• uncle (m/c in eldrely) → Rich (Richter) than Everyone (Evans)
• Remains inside home → Never a/w radiation
• Call 13 (chr 13q del) yr old Naive (Naive B cell) Convent girl () Benet rai () → carrying basket (basket cells)
• Claridribine → Hairy cell leukemia
• smudge her (smudge cells/basket cells)
• Loss Virginity (Loss of vimentin → artefacts)
• Flow on her (Flow cytometry)
• she play flute (Fludarabine)
• CLL all positive → CD23, CD200 +

Chronic Lymphocytic Leukemia (CLL)

• Definition: Blast count very low (not > 20%).

• Age Group: Most common in elderly.

• Genetics: Very commonly deletion 13q.

• Association: Never associated with radiation.

• Orgin: Naive B cell

Diagnosis Criteria:

• Blood:
• Absolute lymphocyte count > 5,000/mm³.

• Bone marrow:
• Lymphocytes > 30%.

• CD Markers: 
• CD5, CD23, CD200 all positive 
  (Mnemonic: CLL →"subkuch positive").

Diagnostic Order:

• Blood sample → Flow cytometry → Bone marrow.

Peripheral Smear:

• Smudge cells (aka basket cells, parachute cells).
• Artifactual due to cell fragility (loss of vimentin).

• Mnemonic: Convent school girl (uniform lymphocytes, some smudged).

Associated Syndromes:

• Evan's Syndrome:
• Warm Ab AIHA + CLL + ITP.
• Mnemonic: "everyone" affected (RBC, WBC, platelet).
• Management: Steroids + Rituximab.

• Richter's Syndrome:
• CLL/SLL → Diffuse Large B Cell Lymphoma (DLBCL).

Chronic Myeloid Leukemia (CML)

 

• Genetics: Translocation 9;22 (Philadelphia chromosome).
• ABR - BCL
• 9 → ABL
• 22 → BCR

• Fusion Protein: BCR-ABL fusion protein → ↑↑↑ tyrosine kinase activity.

• Treatment: Imatinib (tyrosine kinase inhibitor).

• Clinical Feature: 
• Massive splenomegaly 
• "dragging sensation" in abdomen

BCR-ABL Kilodalton Proteins:
(Mnemonic: Alphabetical LMN → ALL, CML, CNL; +3 → +3)

• 190 kD: ALL

• 210 kD: CML

• 230 kD: CNL

Phases (CAB Phases):

• Chronic:
• Blast count < 10%.

• Accelerated:
• Blasts 10-19%.
• Basophils >20%,
• TLC/platelets very high/low,
• spleen not decreasing with therapy.
  (Note: Phase removed by latest WHO, criteria still testable).

• Blast Crisis:
• Blasts ≥ 20%.
• Transforms to acute leukemia
  (commonly AML).

Bone Marrow:

• "Garden party appearance" (diverse cells).

Investigation of Choice: 

• FISH for Philadelphia chromosome (BCR-ABL: red + green → yellow).

Screening Test: 

• LAP Score (Leukocyte/Neutrophil Alkaline Phosphatase).
• Normal: 40-100.
• Reduced (<40) 
• CML, PNH
• Increased (>100):
• Leukemoid reaction,
• pregnancy,
• OCP,
• neutrophilia,
• Down syndrome
  (Mnemonic: "Lakes and Ponds → LPOND").

Chronic Myelomonocytic Leukemia (CMML)

• CMML = MDS/MPN overlap

• Monocytosis is mandatory

• Blast cutoff = 20% (PB + BM combined concept)

WHO 5th Edition (2022)

Prerequisite Criteria

• Must be present in all cases
• Persistent monocytosis
• Absolute ≥ 0.5 × 10⁹/L
• Relative ≥ 10% of leukocytes
• Blasts < 20%
• In peripheral blood
• In bone marrow
• Does NOT meet criteria for
• CML
• Other myeloproliferative neoplasms (MPN)
• No myeloid/lymphoid neoplasms with tyrosine kinase fusions

• Supporting Criteria
• Dysplasia in ≥ 1 myeloid lineage
• Acquired clonal abnormality
• Cytogenetic or molecular
• Abnormal monocyte subset distribution
• Peripheral blood

• Monocytosis Threshold Rules
• Monocytosis ≥ 1 × 10⁹/L
• At least 1 supporting criterion required
• Monocytosis ≥ 0.5 and < 1 × 10⁹/L
• Both required:
• Dysplasia
• Clonal cytogenetic or molecular abnormality

Subtype Classification

• Myelodysplastic CMML (MD-CMML)
• WBC < 13 × 10⁹/L

• Myeloproliferative CMML (MP-CMML)
• WBC ≥ 13 × 10⁹/L

Juvenile myelomonocytic leukemia (JMML)

• Hematopoietic stem cell–derived

• Myeloproliferative neoplasm

• Occurs in early childhood

• Key Hemoglobin Finding
• ↑ HbF for age

• Molecular Pathogenesis
• RAS pathway mutations
• PTPN11
• KRAS
• NRAS
• NF1
• CBL

• Associated / Predisposing Conditions
• Neurofibromatosis type 1
• Noonan syndrome
• Trisomy 8 mosaicism

• Aggressive / Poor Prognosis Types
• PTPN11 mutation
• Neurofibromatosis type 1

• Poor Prognosis

Massive Splenomegaly

• Things ↑↑ spleen size
• Kamal’s belly, Fibres, hair, RBCs, Platelets, Lymphocytes, Betas thala, Black () Malam (), Gocha

• CML

• Primary myelofibrosis

• Polycythemia vera

• Essential thrombocythemia

• Indolent lymphomas

• Hairy cell leukemia

• β-thalassemia major

• Visceral leishmaniasis (Kala-azar)

• Malaria

• Gaucher disease

Myeloproliferative disorders

• Group of disorders with increased production of:
• Red blood cells
• White blood cells
• Platelets

WHO Classification

• Chronic myeloid leukemia (CML)

• Polycythemia vera (PV)

• Primary myelofibrosis (PMF)

• Essential thrombocythemia

• Juvenile myelomonocytic leukemia (JMML)

• Chronic neutrophilic leukemia (CNL)

• Chronic eosinophilic leukemia

• Myeloproliferative neoplasm, not otherwise specified (MPN-NOS)

• Note - CLL not included