Leukemia is cancer of blood-forming tissue such as the bone marrow. Types of leukemia are grouped by the type of cell affected and by the rate of cell growth. Leukemia is either acute or chronic.
Types of Leukemia
There are many different types of leukemia. Some are fast-growing and aggressive, others are slower to progress. Leukemias are also classified based on the type of blood cells affected. The most common types of leukemia include:
Acute leukemia involves an overgrowth of very immature blood cells, also known as blasts. This condition is life-threatening because there are not enough mature blood cells to prevent anemia, infection and bleeding. A diagnosis of acute leukemia is made when there are 20 percent or more blasts in the bone marrow. Acute lymphoblastic leukemia (ALL) is most common during childhood and in early adulthood, although it is also diagnosed in adults 30 years old and older. Acute myelogenous leukemia (AML) occurs more often in adults.
Chronic leukemia involves an overgrowth of mature blood cells. Usually, people with chronic leukemia have enough mature blood cells to prevent serious bleeding and infection. Chronic leukemia is more common in people between ages 40 and 70 and is rare among younger people.
Myelodysplastic Syndrome (MDS) is a condition in which the bone marrow does not function normally and does not produce enough normal blood cells. The blood cells affected are white blood cells, red blood cells and platelets. Some cases of MDS may progress to acute leukemia, over time. MDS is most often found in patients nearing their 60s and 70s.
When your doctor is looking for specific types of leukemia, they will look at chromosome number and appearance, features on the bone marrow cell surface and the appearance of the bone marrow cells under a microscope.
The different types of leukemia share some common symptoms, including:
- Persistent fatigue or feeling of weakness
- Loss of appetite
- Unintentional weight loss
- Easy bruising or bleeding
- Shortness of breath
- Petechiae (tiny red spots under the skin caused by bleeding)
Symptoms of acute lymphoblastic leukemia may also include the presence of painless lumps under the skin in the groin, underarm or neck, and/or pain under the ribs.