## Epidemiology of Childhood Leukemias **Key Point:** Acute lymphoblastic leukemia (ALL) accounts for approximately 75–80% of all childhood leukemias, making it the most common hematologic malignancy in children. ### Incidence and Age Distribution | Leukemia Type | Frequency in Children | Peak Age | Notes | |---|---|---|---| | ALL | 75–80% | 2–5 years | Most common; better prognosis with modern therapy | | AML | 15–20% | All ages; slight increase in infants | Higher mortality rate | | CML | 2–3% | Older children and adolescents | BCR-ABL fusion; tyrosine kinase inhibitor responsive | | Burkitt lymphoma | <1% as leukemia | 5–15 years | Usually lymphoma; leukemic phase rare | ### Clinical Presentation in ALL **High-Yield:** The classic triad in childhood ALL is: 1. Fever (often from infection due to immunosuppression) 2. Pallor and fatigue (from anemia) 3. Petechiae/purpura (from thrombocytopenia) **Clinical Pearl:** The peak incidence of ALL is between 2–5 years of age, which correlates with the patient's age in this vignette. The pancytopenia with 85% blasts is pathognomonic for acute leukemia. ### Why ALL Dominates in Childhood - ALL arises from lymphoid precursor cells, which are more numerous and proliferative in childhood bone marrow. - AML, while more common in adults (especially elderly), is less frequent in young children. - CML is rare in childhood and typically presents in older children or adolescents. - The B-cell precursor subtype (BCP-ALL) accounts for ~85% of childhood ALL cases. **Mnemonic:** **ALL-most common** — ALL is the most common leukemia in children. ### Prognostic Factors - Age 2–5 years is considered favorable. - White blood cell count <50,000/μL at diagnosis is favorable. - Modern chemotherapy protocols (COG, UKALL) achieve cure rates >90% in standard-risk ALL. [cite:Robbins 10e Ch 13]
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.