Types of Leukemia

Chronic Leukemia

The types of leukemia can be grouped based on how quickly the disease develops and gets worse. Leukemia is either chronic or acute:

• Chronic leukemia: Chronic leukemia usually gets worse slowly. Early in the disease, the leukemia cells can still do some of the work of normal white blood cells. People may not have any symptoms at first. Doctors often find chronic leukemia during a routine checkup – before there are any symptoms. Slowly, chronic leukemia gets worse. As the number of leukemia cells in the blood increases, people get symptoms, such as swollen lymph nodes or infections. When symptoms do appear, they are usually mild at first and get worse gradually.
• Acute leukemia: Acute Leukemia usually gets worse quickly. The leukemia cells can’t do any of the work of normal white blood cells. The number of leukemia cells increases rapidly. Acute leukemia usually worsens quickly.

Myeloid Leukemia

The types of leukemia also can be grouped based on the type of white blood cell or bone marrow cells that are affected. Leukemia can start in lymphoid cells or myeloid cells. 

• Leukemia that affects lymphoid cells is called lymphoid, lymphocytic, or lymphoblastic leukemia.
• Leukemia that affects myeloid cells is called myeloid, myelogenous, or myeloblastic leukemia.

Four Most Common Types of Leukemia

1. Chronic lymphocytic leukemia (CLL): CLL affects lymphoid cells and usually grows slowly. It accounts for more than 15,000 new cases of leukemia each year. Most often, people diagnosed with the disease are over age 55. It almost never affects children.
2. Chronic myeloid leukemia (CML): CML affects myeloid cells and usually grows slowly at first. It accounts for nearly 5,000 new cases of leukemia each year. It mainly affects adults.
3. Acute lymphocytic (lymphoblastic) leukemia (ALL): ALL affects lymphoid cells and grows quickly. It accounts for more than 5,000 new cases of leukemia each year. ALL is the most common type of leukemia in young children. It also affects adults.
4. Acute myeloid leukemia (AML): AML affects myeloid cells and grows quickly. It accounts for more than 13,000 new cases of leukemia each year. It occurs in both adults and children.

Less Common Types of Leukemia

• Hairy Cell Leukemia: A rare type of leukemia in which abnormal B-lymphocytes (a type of white blood cell) are present in the bone marrow, spleen, and peripheral blood. When viewed under a microscope, these cells appear to be covered with tiny hair-like projections.