Acute lymphocytic leukemia (ALL) is a type of cancer of the blood and bone marrow — the spongy tissue inside bones where blood cells are made.

The word "acute" in acute lymphocytic leukemia comes from the fact that the disease progresses rapidly and creates immature blood cells, rather than mature ones. The word "lymphocytic" in acute lymphocytic leukemia refers to the white blood cells called lymphocytes, which ALL affects. Acute lymphocytic leukemia is also known as acute lymphoblastic leukemia.

Acute lymphocytic leukemia is the most common type of cancer in children, and treatments result in a good chance for a cure. Acute lymphocytic leukemia can also occur in adults, though the chance of a cure is greatly reduced.

Signs and symptoms of acute lymphocytic leukemia may include:

• Bleeding from the gums

• Bone pain

• Fever

• Frequent infections

• Frequent or severe nosebleeds

• Lumps caused by swollen lymph nodes in and around the neck, armpits, abdomen or groin

• Pale skin

• Shortness of breath

• Weakness, fatigue or a general decrease in energy

Make an appointment with your doctor or your child's doctor if you notice any persistent signs and symptoms that concern you.

Many signs and symptoms of acute lymphocytic leukemia mimic those of the flu. However, flu signs and symptoms eventually improve. If signs and symptoms don't improve as expected, make an appointment with your doctor.

Acute lymphocytic leukemia occurs when a bone marrow cell develops changes (mutations) in its genetic material or DNA. A cell's DNA contains the instructions that tell a cell what to do. Normally, the DNA tells the cell to grow at a set rate and to die at a set time. In acute lymphocytic leukemia, the mutations tell the bone marrow cell to continue growing and dividing.

When this happens, blood cell production becomes out of control. The bone marrow produces immature cells that develop into leukemic white blood cells called lymphoblasts. These abnormal cells are unable to function properly, and they can build up and crowd out healthy cells.

It's not clear what causes the DNA mutations that can lead to acute lymphocytic leukemia.

Factors that may increase the risk of acute lymphocytic leukemia include:

• Previous cancer treatment. Children and adults who've had certain types of chemotherapy and radiation therapy for other kinds of cancer may have an increased risk of developing acute lymphocytic leukemia.

• Exposure to radiation. People exposed to very high levels of radiation, such as survivors of a nuclear reactor accident, have an increased risk of developing acute lymphocytic leukemia.

• Genetic disorders. Certain genetic disorders, such as Down syndrome, are associated with an increased risk of acute lymphocytic leukemia.