Pediatrics · Year 3 · from Pediatrics

Case 2: Acute Lymphoblastic Leukemia

Patient Demographics

  • Age: 4-year-old male
  • Sex: Male

Chief Complaint

"He's been tired, bruising easily, and has had fevers."

History of Present Illness

A 4-year-old previously healthy male is brought in with 3 weeks of progressive fatigue, decreased appetite, and intermittent fevers. His parents have noticed increased bruising, particularly on his legs, and bleeding from his gums when brushing teeth. He has been complaining of leg pain that wakes him at night. He has had no recent illnesses or sick contacts. He was in his usual state of good health until 3 weeks ago when his preschool teacher noted he seemed tired and was not playing as actively as usual.

Physical Examination

  • General: Pale, fatigued-appearing child
  • Vital signs: Temp 38.1°C, HR 110 bpm, RR 22/min, BP 95/60 mmHg
  • HEENT: Pale conjunctivae, petechiae on soft palate, gingival bleeding
  • Lymph nodes: Bilateral cervical lymphadenopathy (multiple 1-2 cm nodes), bilateral axillary and inguinal lymphadenopathy
  • Cardiovascular: Tachycardic, II/VI systolic flow murmur
  • Respiratory: Clear to auscultation
  • Abdomen: Hepatomegaly (liver 4 cm below costal margin), splenomegaly (spleen 5 cm below costal margin)
  • Extremities: Multiple ecchymoses on lower extremities, tenderness to palpation of tibias
  • Skin: Scattered petechiae

Workup

  • CBC: WBC 45,000/μL, Hgb 6.2 g/dL, Platelets 18,000/μL
  • Peripheral smear: 65% lymphoblasts with high N:C ratio, scant cytoplasm
  • CMP: Na 136, K 4.8, BUN 22, Cr 0.6, LDH 1,850 U/L, Uric acid 8.5 mg/dL
  • Coagulation studies: PT/INR normal, PTT normal, Fibrinogen normal
  • Bone marrow aspirate: 92% lymphoblasts; Flow cytometry: CD10+, CD19+, TdT+ (B-cell precursor ALL)
  • Cytogenetics: High hyperdiploidy (favorable)
  • Lumbar puncture: No blasts in CSF (CNS negative)
  • Chest X-ray: No mediastinal mass

Diagnosis

B-cell precursor acute lymphoblastic leukemia, standard risk

Clinical Reasoning

This child presents with the classic constellation of ALL: pancytopenia causing fatigue/pallor (anemia), bruising/petechiae/bleeding (thrombocytopenia), and fever (neutropenia). Lymphoblasts in the peripheral blood and bone marrow confirm the diagnosis. The bone pain reflects marrow expansion. Hepatosplenomegaly and lymphadenopathy result from leukemic infiltration. Risk stratification is favorable: age 1-10 years, WBC <50,000, B-cell immunophenotype, favorable cytogenetics (hyperdiploidy), and CNS-negative. The elevated LDH and uric acid indicate high cell turnover and risk for tumor lysis syndrome with treatment initiation.

Management

  1. Tumor lysis syndrome prevention: IV fluids 3 L/m²/day, allopurinol or rasburicase, monitor electrolytes Q6h
  2. Transfusion support: Packed RBCs for anemia, platelets to maintain >10,000 (or >50,000 for procedures)
  3. Infection prevention: Neutropenic precautions; low threshold for empiric antibiotics if febrile
  4. Chemotherapy: Induction therapy per COG protocol (vincristine, dexamethasone, PEG-asparaginase, +/- daunorubicin)
  5. Central line placement: For chemotherapy administration
  6. Family support: Social work, child life services, education about treatment plan
  7. Expected outcome: >95% remission rate with induction; overall survival >90% for standard-risk B-ALL

Clinical Image

Image Description: Peripheral blood smear demonstrating abnormal blood cells, illustrating the hematologic findings in pediatric malignancies.

Source: Wikimedia Commons URL: https://commons.wikimedia.org/wiki/File:Sickle_cells.jpg License: CC BY-SA 3.0

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