Lecture Notes: Leukemia in Children

Overview

• Leukemia: Malignant transformation and proliferation of hematopoietic cells.
  • Acute Leukemia: Clonal expansion of immature precursors.
  • Chronic Leukemia: Mature bone marrow components becoming clonal.
• Symptoms: Due to lack of normal bone marrow cell production or accumulation of malignant cells.

Epidemiology

• Most common pediatric malignancy.
• 30% of all newly diagnosed children with cancer have leukemia.
• Higher incidence in boys than girls.

Types of Leukemia in Children

1. Acute Lymphoblastic Leukemia (ALL)
   • Most common in children.
   • Proliferation of B and T cell lymphocyte precursors.
   • Typically affects children aged 2-5.
   • Higher risk in Caucasian children.
2. Acute Myelogenous Leukemia (AML)
   • Clonal proliferation of myeloid precursors.
   • Bimodal incidence: peaks in children under 2 and in adolescence.
   • Equal incidence in boys and girls.
   • Strong association with Down syndrome.
3. Chronic Myelogenous Leukemia (CML)
   • Uncontrolled growth of myeloid cells.
   • Incidence increases with age.
   • Associated with BCR-ABL fusion protein.
4. Juvenile Myelomonocytic Leukemia (JMML)
   • Rare, usually diagnosed before age 3.
   • Associated with genetic conditions like Down syndrome and neurofibromatosis.

Symptoms of Leukemia

• Lethargy, fatigue.
• Respiratory distress, bone pain.
• Fever, pallor, tachycardia.
• Bruising, petechiae, lymphadenopathy, hepatosplenomegaly.
• Testicular enlargement in boys.
• CNS involvement, especially in ALL.

Diagnosis

• CBC: Shows abnormal cell lines, presence of blasts.
• Chemistry panel: Checks for tumor lysis syndrome.
• Radiology: Chest X-ray for mediastinal mass.
• Bone Marrow Aspiration/Biopsy: Confirm diagnosis.
• Lumbar Puncture: Check for CNS involvement in ALL.

High-Risk Factors

• Age less than 1 year or more than 10 years.
• Very high white blood cell count.
• T-cell phenotype.
• Cytogenic changes in leukemia cells.
• Poor response to therapy.

Treatment

• ALL: Multi-agent chemotherapy for 2-3.5 years, prophylactic intrathecal chemotherapy/radiation.
• AML: Multi-agent chemotherapy for 6-9 months, possible stem cell transplant.
• CML: Tyrosine kinase inhibitors, possible stem cell transplant.
• JMML: Often requires a bone marrow transplant.

Prognosis

• ALL: 80-95% survival in low-risk groups.
• AML: 50% survival rate, depending on subtype.
• CML: Lifelong disorder managed with therapy.
• JMML: 40% survival with bone marrow transplant.

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This concludes the review of leukemia in children. The prognosis is generally good for ALL, despite it being a cancer diagnosis.