Acute Leukemias

Jun 18, 2024

Acute Leukemias

Introduction

  • Acute leukemias are a type of blood cancer, often referred to as blood cancer.
  • They involve the cancerous proliferation of immature blood cells, or blasts.

Hematopoiesis Overview

  • Hematopoietic Stem Cell (HSC): CD34 positive, divides into myeloid and lymphoid blasts.
  • Myeloid Lineage: Myeloid stem cells divide into different blasts:
    • Erythroblasts: Produce RBCs
    • Myeloblasts: Produce granulocytes (neutrophils, basophils, eosinophils)
    • Monoblasts: Produce monocytes
    • Megakaryoblasts: Produce megakaryocytes (platelets)
  • Lymphoid Lineage: Lymphoid stem cells produce:
    • B Lymphoblasts: Form B cells -> Plasma cells
    • T Lymphoblasts: Form T cells (CD4 and CD8)

Acute Leukemias

  • Neoplastic proliferation of blasts (immature cells).
  • More than 20% blasts in bone marrow needed for diagnosis.
  • Crowding of bone marrow with blasts hinders normal blood cell production.

Symptoms of Acute Leukemias

  • Anemia: Fatigue due to reduced RBC production.
  • Leukopenia/Neutropenia: Increased risk of infections.
  • Thrombocytopenia: Increased bleeding risk.
  • Pancytopenia: General reduction in various blood cell types.

Classification

  • Two main types based on the type of blast proliferating:
    • Acute Myeloid Leukemia (AML): Proliferation of myeloid blasts.
    • Acute Lymphoblastic Leukemia (ALL): Proliferation of lymphoid blasts.

Acute Lymphoblastic Leukemia (ALL)

Overview

  • Neoplastic Proliferation: More than 20% lymphoblasts in bone marrow.
  • Markers: Characterized by TDT positivity.
  • Commonly seen in children, especially those with Down Syndrome (after 5 years of age).

Types of ALL

  • B-ALL: B lymphoblasts; express CD10, CD19, CD20.
    • Most common type of ALL
    • Good prognosis, especially with t(12;21) translocation
    • Bad prognosis with t(9;22) (Philadelphia chromosome)
    • Requires prophylactic chemotherapy to CNS and testes.
  • T-ALL: T lymphoblasts; express CD markers from CD2 to CD8.
    • Common in teenagers
    • Often presents with a thymic (mediastinal) mass
    • Can also be termed acute lymphoblastic lymphoma if a solid mass forms.
    • Does not express CD10.

Conclusion

  • Understanding the types, diagnosis, and implications of acute leukemias is crucial for proper management.
  • Differentiation between AML and ALL as well as subtypes of ALL is essential for treatment planning.