What is Leukemia?

Leukemia is a malignant disease (cancer) of the bone marrow and blood. It is characterized by the uncontrolled accumulation of blood cells. Leukemia is divided into four categories: myelogenous or lymphocytic, each of which can be acute or chronic. The terms myelogenous or lymphocytic denote the cell type involved. The are four major types of leukemia.

1. Acute Myelogenous Leukemia (AML)
2. Acute Lymphocytic Leukemia (ALL)
3. Chronic Myelogenous Leukemia (CML)
4. Chronic Lymphocytic Leukemia (CLL)

The terms lymphocytic or lymphoblastic indicate that the cancerous change takes place in a type of marrow cell that forms lymphocytes. The terms myelogenous or myeloid indicate that the cell change takes place in a type of marrow cell that normally goes on to form red cells, some types of white cells, and platelets.

Acute lymphocytic leukemia and acute myelogenous leukemia are each composed of blast cells, known as lymphoblasts or myeloblasts. Acute leukemias progress rapidly without treatment.

Chronic leukemias have few or no blast cells. Chronic lymphocytic leukemia and chronic myelogenous leukemia usually progress slowly compared to acute leukemias.

The previous information is from the Society and there is more info at:

http://www.leukemia-lymphoma.org/all_page?item_id=7026