Britannica
Sources used in this answer
How does leukemia begin in blood-forming tissues?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
blood disease
Peripheral blood smear revealing histopathologic features indicative of a blast crisis in a case of chronic myelogenous leukemia (CML). Blast crisis occurs when one-fifth to one-third of the cells in the blood or bone marrow are immature blood cells, or blast cells. This phase of CML is characterized by fever, weakness, and an enlarged spleen.
Leukemia begins in the bone marrow through a genetic change, or mutation, occurring in an early progenitor cell, known as a stem cell.1
This initial mutation affects genes that regulate vital aspects of cell growth and function, such as oncogenes. Once this genetic alteration occurs, the mutant cell passes the change on to all of its progeny, eventually creating a clone of leukemic cells. This process typically involves multiple steps that culminate in the development of cells possessing malignant attributes. These leukemic cells then continue to divide within the bone marrow, often leading to an increase in the number of white blood cells in the circulation or marrow itself.12