Acute Lymphoblastic Leukemia (ALL)

Snapshot

• A 11-year-old girl with Down syndrome presents with a few weeks of low-grade fever. She is otherwise feeling well, with no signs of infection. Blood-work shows elevated WBCs, low neutrophil count, and anemia. Blood cultures are drawn and come back positive for Pseudomonas.

Introduction

• Acute leukemia of lymphoid precursor cells that occurs in children
• Crowding of bone marrow leads to bone marrow failure
• Subtypes
  • B-cell ALL – 85% of all ALL
    • CD10+ and CD19/20+  
    • TdT+ (marker of precursor T- or B-cell)
  • T-cell ALL 
    • CD2+, CD8+, and CD3+
    • TdT+ (marker of precursor T- or B-cell)
    • commonly presents as mediastinal mass
      • infiltration of thymus 
• Epidemiology
  • < 15 years
  • most common type of cancer and leukemia in children
• Associated conditions
  • Down syndrome in children > 5 years  
• leukemia in Down syndrome children < 5 years = AML

Presentation

• Symptoms
  • most common symptom is fever
  • acute onset
    • recurrent infections
    • bleeding
    • fatigue
• Physical exam
  • mediastinal mass from infiltration of thymus 
  • hepatosplenomegaly
• lymphadenopathy   

Evaluation

• Peripheral blood smear
  • ↑ lymphoblasts (high nuclei to cytoplasm ratio)
• CBC reflects bone marrow failure
  • anemia
  • thrombocytopenia
  • ↓ mature WBCs
• Bone marrow aspiration with cytogenetics
  • ↑ lymphoblasts
  • TdT+, a marker of pre-T and pre-B cells
  • T-cell ALL
    • CD2+
    • CD3+
  • B-cell AML
    • CD10+
    • CD19+
  • negative MPO (myeloperoxidase)
• t(12:21) 

Differential Diagnosis

• AML 
• B-cell lymphoma
• Non-hodgkin lymphoma 

Treatment

• Chemotherapy
• Prophylaxis to CNS (standard chemotherapy does not penetrate blood-brain barrier)
• intrathecal chemotherapy

Prognosis, Prevention, and Complications

• Prognosis
  • very responsive to therapy
• Complications
• likes to spread to CNS and testes