Hematopoietic Process and Leukemia Overview

Introduction to Hematopoiesis

Hematopoietic Stem Cells (HSCs): Origin of all blood cells.
Differentiation Paths:
- Myeloid Stem Cells: Develop into red cells, white cells (excluding lymphocytes), and platelets.
- Lymphoid Stem Cells: Develop into lymphocytes.
Key Differentiations:
- Lymphoid stem cells become lymphoblasts.
- Myeloid stem cells give rise to all other blood cells except lymphocytes.

Myeloblasts: Stay in the bone marrow for maturation.
Lymphoblasts: Some stay in the bone marrow, others travel to lymphoid organs (thymus for T-cells, spleen, and lymph nodes).

Definition: Malignant disorders of blood/bone marrow characterized by uncontrolled proliferation of leukocytes.
Common Types:
- Acute Lymphocytic Leukemia (ALL)
- Acute Myelocytic Leukemia (AML)
- Chronic Lymphocytic Leukemia (CLL)
- Chronic Myelocytic Leukemia (CML)
Characteristics of Acute Leukemias:
- Rapid progression.
- High number of blast cells (immature).
- Immediate treatment required to prevent fatality.
Characteristics of Chronic Leukemias:
- Slower progression.
- Mature but abnormal cells.

Acute Leukemias:
- Overcrowding of bone marrow due to blast cells.
- Pancytopenia due to suppression of normal hematopoiesis.
- Symptoms include anemia, neutropenia, and thrombocytopenia.
- Bone and joint pain, hypermetabolism resulting in weight loss and cachexia.

Complete Blood Count (CBC): Checks for abnormalities in blood cells.
Bone Marrow Biopsy: Essential for diagnosis.
- Presence of excessive myeloblasts suggests AML.
- Presence of lymphoblasts suggests ALL.
Special Markers: Some forms of AML show Auer rods (linked to vitamin A).

Understanding the hematopoietic process is crucial for grasping leukemia pathophysiology.
Different leukemias are characterized based on cell types involved and progression speed.
Accurate diagnosis relies heavily on blood tests and bone marrow biopsies.