Leukemia's Lab Diagnosis (ALL, AML, CLL, and CML)

Laboratory Diagnosis of Leukemias

I. Acute Myeloid Leukemia (AML)

1. Complete Blood Count (CBC)

  • Anemia – normocytic, normochromic (↓ RBCs, Hb)
  • Thrombocytopenia – ↓ platelet count
  • Leukocytosis – ↑ WBC count (in most cases)
  • Blast cells in peripheral smear – >20% blasts (WHO criterion)

2. Peripheral Blood Smear

  • Myeloblasts – large cells with:

    • High N:C ratio
    • Fine chromatin
    • 1–4 nucleoli
    • Auer rods – (needle-like azurophilic granules; diagnostic of myeloid lineage)

3. Bone Marrow Aspiration & Biopsy

  • Hypercellular marrow
  • >20% myeloblasts
  • Suppressed normal hematopoiesis

4. Cytochemistry

  • Myeloperoxidase (MPO) positive – (confirms myeloid origin)
  • Sudan Black B (SBB) positive
  • Non-specific esterase negative

5. Immunophenotyping (Flow Cytometry)

  • CD13, CD33, CD117 – markers of myeloid lineage
  • HLA-DR, CD34 (stem cell markers)

6. Cytogenetic & Molecular Studies

  • t(8;21), inv(16), t(15;17) (PML-RARA in APL subtype)
  • FLT3, NPM1 mutations (prognostic markers)

II. Acute Lymphoblastic Leukemia (ALL)

1. Complete Blood Count (CBC)

  • Anemia
  • Thrombocytopenia
  • Variable WBC count – may be low, normal, or high
  • Blasts in peripheral blood – lymphoblasts

2. Peripheral Blood Smear

  • Lymphoblasts – small to medium cells with:

    • Scant cytoplasm
    • Condensed chromatin

3. Bone Marrow Aspiration

  • >20% lymphoblasts
  • Suppressed normal hematopoiesis

4. Cytochemistry

  • MPO negative
  • SBB negative
  • PAS positive (Periodic acid–Schiff reaction)

5. Immunophenotyping

  • B-ALL: CD10, CD19, CD22, TdT+
  • T-ALL: CD3, CD7, TdT+

6. Cytogenetics

  • t(12;21) – good prognosis
  • t(9;22) BCR-ABL (Philadelphia chromosome) – poor prognosis
  • Hyperdiploidy or hypodiploidy – prognostic value

III. Chronic Myeloid Leukemia (CML)

1. CBC

  • Marked leukocytosis (often >100,000/µL)
  • Anemia – mild to moderate
  • Thrombocytosis – common in early phase

2. Peripheral Blood Smear

  • All stages of myeloid maturation present:
    • Myeloblasts, promyelocytes, myelocytes, metamyelocytes, neutrophils, basophils
  • Basophilia & eosinophilia
  • Few blasts (<10%)

3. Bone Marrow Aspiration

  • Hypercellular with granulocytic hyperplasia
  • Myeloid to erythroid (M:E) ratio increased

4. LAP Score (Leukocyte Alkaline Phosphatase)

  • Low in CML (differentiates from leukemoid reaction)

5. Cytogenetics / Molecular

  • Philadelphia chromosome (t(9;22)(q34;q11))

  • BCR-ABL fusion gene
  • Detected by FISH, RT-PCR

IV. Chronic Lymphocytic Leukemia (CLL)

1. CBC

  • Absolute lymphocytosis (>5,000/µL mature lymphocytes)
  • Anemia and thrombocytopenia – late stages

2. Peripheral Blood Smear

  • Small mature lymphocytes with clumped chromatin
  • Smudge cells – (ruptured lymphocytes during smear prep)

3. Bone Marrow

  • Hypercellular marrow with lymphoid infiltration
  • Pattern: nodular, interstitial, or diffuse infiltration

4. Immunophenotyping

  • CD5+, CD19+, CD20+, CD23+
  • Weak surface immunoglobulin

5. Cytogenetic Abnormalities

  • del(13q), trisomy 12, del(11q), del(17p)
  • ZAP-70, CD38 expression – adverse prognosis

Comparative Table:

Feature / Test Acute Myeloid Leukemia (AML) Acute Lymphoblastic Leukemia (ALL) Chronic Myeloid Leukemia (CML) Chronic Lymphocytic Leukemia (CLL)
Age group commonly affected Adults (especially >40 years) Children (peak at 2–5 years) Adults (typically 40–60 years) Elderly (median age ~70 years)
Complete Blood Count (CBC) ↓ Hemoglobin, ↓ Platelets, ↑ or ↓ WBCs with circulating myeloblasts ↓ Hemoglobin, ↓ Platelets, ↑ or ↓ WBCs with circulating lymphoblasts ↑↑ WBCs (often >100,000/µL), mild anemia, normal or ↑ platelets ↑ Lymphocyte count (>5,000/µL), late ↓ Hb and platelets
Peripheral Blood Smear Large myeloblasts with high N:C ratio, fine chromatin, nucleoli, Auer rods Small-medium lymphoblasts with scant cytoplasm, condensed chromatin, indistinct nucleoli Myeloid precursors at all stages: myeloblasts → neutrophils; basophilia, eosinophilia Small mature lymphocytes, smudge cells (fragile cells ruptured on smear)
Blasts in Peripheral Smear >20% myeloblasts >20% lymphoblasts <10% blasts Rare or absent
Bone Marrow Examination Hypercellular, >20% myeloblasts, ↓ normal hematopoiesis Hypercellular, >20% lymphoblasts, ↓ normal hematopoiesis Hypercellular with granulocytic hyperplasia, ↑ M:E ratio Hypercellular with diffuse/nodular lymphocytic infiltration
Cytochemistry MPO+, Sudan Black B+, NSE− MPO−, Sudan Black B−, PAS+ MPO weakly positive Negative
Immunophenotyping (Flow Cytometry) CD13, CD33, CD117, HLA-DR, CD34 (stem/myeloid markers) B-ALL: CD10, CD19, CD22, TdT+; T-ALL: CD3, CD7, TdT+ Myeloid markers; BCR-ABL expression (fusion protein) CD19, CD20, CD5, CD23, weak surface Ig
Cytogenetics / Molecular Testing t(8;21), inv(16), t(15;17/PML-RARA), FLT3, NPM1 mutations t(12;21) (good prognosis), t(9;22) BCR-ABL (poor prognosis), hyper-/hypodiploidy Philadelphia chromosome t(9;22) → BCR-ABL fusion gene del(13q), del(11q), del(17p), trisomy 12; ZAP-70+, CD38+ (poor prognosis)
Leukocyte Alkaline Phosphatase (LAP) Not used Not used ↓ LAP score (helps differentiate from leukemoid reaction) Normal
Special Findings Auer rods are pathognomonic PAS block positivity in blasts Basophilia, Eosinophilia, BCR-ABL gene detected by FISH or PCR Smudge cells, clonal B-lymphocytes, hypogammaglobulinemia
Other Laboratory Findings ↑ LDH, ↑ uric acid (due to tumor lysis), prolonged PT/PTT in APL subtype ↑ LDH, ↑ uric acid; CSF analysis if CNS involvement suspected ↑ LDH, ↑ uric acid, possible splenomegaly on imaging ↑ LDH, ↓ immunoglobulin levels (may lead to recurrent infections)

Key Terms:

  • Blasts: Immature precursor cells; high numbers in blood suggest acute leukemia.
  • Auer Rods: Needle-like azurophilic granules in AML myeloblasts (confirm myeloid lineage).
  • MPO (Myeloperoxidase): Enzyme present in myeloid cells; positive in AML.
  • PAS (Periodic Acid–Schiff): Stains glycogen in lymphoblasts; positive in ALL.
  • CD Markers: Cell surface proteins used to identify lineage (e.g., CD19 = B-cells).
  • Philadelphia Chromosome (t(9;22)): Translocation forming BCR-ABL, found in CML (and some ALL).
  • Smudge Cells: Damaged fragile lymphocytes, common in CLL.
  • ZAP-70 and CD38: Predict poor prognosis in CLL.


Comments

Post a Comment

Popular posts from this blog

Blood Vessels

Image
Blood Vessels and Their Structure 🔄 General Function of Blood Vessels Blood vessels form a closed circuit for blood to circulate throughout the body. Oxygen-rich blood is pumped from the left side of the heart , travels to all body cells, and returns oxygen-poor blood to the right side of the heart . 🛤️ Types of Blood Vessels Blood travels through the following vessels in order: Arteries – carry blood away from the heart. Arterioles – smaller branches of arteries. Capillaries – the smallest vessels where exchange of gases and nutrients occurs. Venules – small veins collecting blood from capillaries. Veins – carry blood back to the heart. 🧠 Arteries: Structure & Types Arteries are classified based on size and wall structure into: Type Key Features Large (Elastic) Rich in elastic tissue . Example: Aorta. Medium (Muscular) Rich in smooth muscle . Example: Coronary arteries. Arterioles Smallest arteries, control blood flow...
Read more

Lymphoid System

Lymphoid System I. Components of the Lymphoid System 1. Lymphatic Vessels Structure : Composed of lymphatic capillaries, vessels, and nodes. Lymphatic Capillaries : Resemble blood capillaries. Have thin walls with a single endothelial cell layer. Highly permeable—allow passage of fluid, proteins, and particulate matter. Larger Lymphatics : Structurally similar to veins but with thinner muscle layers. More numerous valves than veins. Function : Drain excess tissue fluid (lymph). Return lymph to the bloodstream. Help in immune surveillance and transport of immune cells. 2. Lymph Nodes (Normal Structure) Gross Anatomy : Bean-shaped or oval. 1–2 cm in length. Covered by a fibrous capsule. Entry & Exit of Lymph : Afferent lymphatics enter at convex surface. Drain into subcapsular sinus → branches → exit via efferent lymphatic at the hilum. Internal Structure : Cortex : Contains B-cell rich lymphoid follic...
Read more

Heart

Image
The Heart Normal Structure 1. Anatomy and Physiology Heart Function : Muscular pump that circulates blood through the body. Weight : Adult Male: 300-350 gm Adult Female: 250-300 gm Chambers : Right Atrium and Left Atrium (superior) Right Ventricle and Left Ventricle (inferior and larger) Septa: Interatrial septum : Thin wall between atria. Interventricular septum : Thick wall between ventricles. Wall Thickness: Right Ventricle : 0.3–0.5 cm Left Ventricle : 1.3–1.5 cm 2. Blood Flow Pathway Systemic veins → Right atrium → Right ventricle → Pulmonary arteries → Lungs → Pulmonary veins → Left atrium → Left ventricle → Aorta → Systemic arteries 3. Cardiac Valves Atrioventricular (AV) Valves : Tricuspid valve (right) Mitral/Bicuspid valve (left) Semilunar Valves  : Pulmonary valve Aortic valve 4. Wall Layers of the Heart Epicardium (Visceral Pericardium) : Outer covering Myocardium : Muscle l...
Read more