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AML, CML, ALL, CLL

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• 3 min read
AML, CML, ALL, CLL
Photo by National Institute of Allergy and Infectious Diseases / Unsplash

Acute Myeloid Leukemia (AML)

  • Definition: Malignant proliferation of myeloblasts (>20% blasts in bone marrow).
  • Common in: Adults, especially >60 years.
  • Risk factors: Previous chemotherapy/radiation, myelodysplastic syndromes, exposure to benzene.
  • Presentation: Fatigue, anemia, infections, bleeding (petechiae, bruising).
  • Labs:
    • ↑ WBC with blasts
    • ↓ Platelets, anemia
    • Auer rods (pathognomonic)
  • Diagnosis: Bone marrow biopsy showing >20% myeloblasts.
  • Treatment:
    • Induction chemotherapy (e.g., cytarabine + anthracycline)
    • Possible allogeneic stem cell transplant
    • t(15;17) in APML subtype treated with All Trans Retinoic Acid (ATRA)

Chronic Myeloid Leukemia (CML)

  • Definition: Myeloproliferative disorder with uncontrolled production of mature granulocytes.
  • Genetics: Philadelphia chromosome t(9;22) → BCR-ABL fusion gene (constitutive tyrosine kinase activity).
  • Presentation: Often asymptomatic or fatigue, weight loss, splenomegaly, night sweats.
  • Labs:
    • Increased hematopoietic proliferation
      • Markedly elevated WBC count (leukocytosis) with left shift (myelocytes, metamyelocytes)
      • Basophilia/eosinophilia is common
    • Low LAP score (differentiates from leukemoid reaction)
  • Phases: Chronic → Accelerated → Blast crisis
  • Treatment:
    • Tyrosine kinase inhibitors (imatinib, dasatinib)
    • Allogeneic stem cell transplant for blast crisis or refractory disease

Acute Lymphoblastic Leukemia (ALL)

  • Definition: Malignant proliferation of lymphoblasts (>20% blasts).
  • Common in: Children (the most common childhood leukemia), but also adults.
  • Presentation: Fatigue, fever, bleeding, bone pain, lymphadenopathy, hepatosplenomegaly, CNS symptoms (headache, vomiting).
  • Labs:
    • ↑ WBC (leukocytosis) with lymphoblasts
      • Large nucleus (scant cytoplasm), visible nucleolus
    • Anemia, thrombocytopenia
  • Diagnosis: Bone marrow biopsy with >20% lymphoblasts; TdT+ (terminal deoxynucleotidyl transferase).
  • Subtypes: B-ALL (most common), T-ALL (often mediastinal mass).
  • Treatment: Chemotherapy + CNS prophylaxis (intrathecal methotrexate).
  • Prognosis: Good in children, worse in adults.
  • Associations: Down syndrome (risk for ALL and AML).

Chronic Lymphocytic Leukemia (CLL)

  • Definition: Clonal proliferation of mature, small CD5+ B lymphocytes.
  • Common in: Older adults (>60 years).
  • Presentation: Often asymptomatic, lymphadenopathy, hepatosplenomegaly, “B symptoms” (fever, night sweats, weight loss), autoimmune hemolytic anemia.
  • Labs:
    • Lymphocytosis with small mature lymphocytes
    • Smudge cells on peripheral smear
  • Diagnosis: Flow cytometry showing CD5+, CD19+, CD20+ B cells.
  • Treatment: Observation if asymptomatic; chemo/immunotherapy if symptomatic.
  • Complications: Richter transformation (to aggressive lymphoma).

AML (Acute Myeloid Leukemia):

  • More common in adults (median ~65 years) but can occur at any age
  • Acute symptoms similar to ALL (fatigue, infections, bleeding)
  • Sometimes gum hypertrophy, skin lesions (myeloid sarcoma)
  • Peripheral smear: myeloblasts, Auer rods

CML (Chronic Myeloid Leukemia):

  • Typically affects adults (40-60 years)
  • Chronic phase: often asymptomatic or fatigue, splenomegaly
  • Labs: very high WBC count with left shift (all myeloid precursors)
  • Presence of Philadelphia chromosome (BCR-ABL)
  • May progress to blast crisis (like AML)

ALL (Acute Lymphoblastic Leukemia):

  • Most common in children (peak 2-5 years)
  • Acute onset of fatigue, fever, bleeding (due to marrow failure)
  • Often bone pain and lymphadenopathy
  • May present with a mediastinal mass (especially T-cell ALL)
  • Peripheral smear: lymphoblasts

CLL (Chronic Lymphocytic Leukemia):

  • Usually affects older adults (>60)
  • Often asymptomatic, found incidentally on CBC
  • Symptoms when present: painless lymphadenopathy, fatigue
  • Peripheral smear: smudge cells, mature small lymphocytes
  • Slow progression

Hodgkin’s Lymphoma:

  • Biphasic age distribution: young adults and >55 years
  • Presents with painless lymphadenopathy (often cervical)
  • Classic B symptoms (fever, night sweats, weight loss)
  • Diagnosis requires lymph node biopsy showing Reed-Sternberg cells
Understanding Hodgkins Lymphoma
Hodgkin’s lymphoma (also known as Hodgkin’s disease) is a type of cancer that affects the lymphatic system and originates from B cells, which are important components of our immune system responsible for the memory and development of antibodies. Who Does Hodgkin’s Lymphoma Affect? Hodgkin’s lymphoma has a bimodal distribution, meaning
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  • Child with acute fatigue, bone pain, mediastinal mass → ALL
  • Older adult with high WBC, splenomegaly, Philadelphia chromosome → CML
  • Older adult with painless lymphadenopathy, smudge cells on smear → CLL
  • Adult with acute gum hypertrophy, infections, blasts with Auer rods → AML
  • Young adult with painless cervical lymphadenopathy, night sweats → Hodgkin’s lymphoma

Leukemoid Reaction

  • A reactive, benign, marked increase in white blood cells (usually neutrophils) in response to infection or stress, mimicking leukemia.
  • Causes:
    • Severe bacterial infections (e.g., Clostridium difficile, C. diphtheriae)
    • Stress, trauma, and inflammation
    • Certain drugs (e.g., corticosteroids)
    • Hemolysis or hemorrhage
  • WBC count: Very high, often >50,000/µL, with increased mature neutrophils and band forms.
  • Peripheral smear: Left shift (increased bands, metamyelocytes, myelocytes), but no blasts.
  • Key differentiators from CML:
    • High LAP score in leukemoid reaction vs. low in CML.
    • Negative Philadelphia chromosome/BCR-ABL gene
    • No basophilia in leukemoid reaction.
  • Management: Treat underlying cause; leukemoid reaction resolves.