Leukemia is a cancer of the blood and bone marrow. “Leuko” means white, and “emia” means blood, so the name points to how the disease often causes an excess of abnormal white blood cells. It begins when immature blood cells multiply abnormally and crowd out healthy ones. But leukemia isn’t one single disease. It comes in several forms, and knowing which one someone has is key for treatment and prognosis.
Doctors first divide leukemia into acute and chronic forms:
Acute leukemias develop quickly, with cells that haven’t matured — like infants that never grow into adults. Symptoms such as fatigue, infections, or bleeding may appear suddenly, and treatment must often begin quickly. Chronic leukemias progress more slowly. The cells are a bit more mature, and in many cases people live for years with abnormal blood counts before symptoms force treatment.
The next division is based on which cell family is affected: lymphoid or myeloid. Lymphoid leukemia involves the lymphoid line — cells that develop into lymphocytes, the body’s infection-fighting defenders. Myeloid leukemia involves cells that would normally become red blood cells (carry oxygen), platelets (help blood clot), or certain white blood cells (fight bacteria).
The four main types from combining these two categories are:
Acute lymphoblastic leukemia (ALL): fast growing, starts in immature lymphocytes, and is the most common leukemia in children.
Acute myeloid leukemia (AML): begins in the myeloid line, also grows quickly, and is more common in adults but can occur at any age.
Chronic lymphocytic leukemia (CLL): affects lymphocytes, usually slow growing, often seen in older adults.
Chronic myeloid leukemia (CML): affects the myeloid line. Modern targeted medicines have turned it into a disease many people can live with for years.
Childhood leukemia is not a different disease on its own, but the term is used because leukemia is the most common cancer in children. Most cases are acute lymphoblastic leukemia (ALL), with fewer cases of acute myeloid leukemia (AML). Highlighting childhood leukemia helps remind us that while it is serious, survival rates in children have improved dramatically with today’s treatments.
Other less common types include:
Hairy cell leukemia (HCL): a slow-growing cancer of B lymphocytes. The cells have tiny projections that look “hairy” under the microscope. It often causes fatigue, low blood counts, and spleen enlargement.
Hairy cell leukemia variant (HCL-V): less common and usually more aggressive than classic HCL.
Myelodysplastic syndromes (MDS): not officially leukemia, but a related group of marrow disorders where blood cells don’t form normally. In some cases, MDS can progress into acute myeloid leukemia (AML).
Knowing whether leukemia is acute or chronic, lymphoid or myeloid, or a rarer form like HCL — and being aware of related conditions such as MDS — is the starting point for understanding the disease. These names may look long and technical, but each tells something real about how the cancer behaves and why one person may need immediate treatment while another can be safely monitored.
Copyright © 2025 CMedEd.com
