What is leukemia?

Leukemia is a cancer of the blood. It is the most common cancer that affects children. Leukemia starts in the bone marrow (the soft, spongy tissue inside most bones). Bone marrow is where our bodies make blood cells, including different types of white blood cells (cells that help fight infections and illness), red blood cells and platelets.

In children with leukemia, their bone marrow makes white blood cells that grow out of control and spread throughout the bloodstream. These white blood cells do not work the same as typical cells. Leukemia can affect one or more of the different types of white blood cells.

The abnormal white blood cells are called blasts. Blast cells do not develop into working white blood cells or help fight infection. They also crowd out normal blood cell production in the bone marrow.

How common is leukemia in children in Latin America?

In Mexico, between 5,000-6,000 children are diagnosed with cancer every year.i About 5 out of every 10 of these children are diagnosed with leukemia. Most children are diagnosed when the leukemia is in its later stages (about 70%, or 7 out of every 10).ii

In Peru, about 1,300 children are diagnosed with cancer every year. Leukemia makes up 1 out of every 3 childhood cancer cases.iii

In Colombia, about 6,218 children were diagnosed with cancer in 2018. Acute lymphoid leukemia (ALL) is the most common type of childhood cancer in the country.iv

What makes up our blood?

Blood is made up on 3 main types of cells that live in a fluid called plasma. The main blood cell types include red blood cells, white blood cells and platelets. Children with leukemia often have lower levels of these cells than children without leukemia.

Red blood cells

Erythrocytes are red blood cells that carry oxygen. Children with leukemia often have anemia (lower levels of erythrocytes than usual).

White blood cells

There are many types of white blood cells. Leukemia in children most often starts in a lymphoid stem cell or a myeloid stem cell. Both lymphoid and myeloid stem cells are in the bone marrow. Stem cells are cells that have the potential to develop into other types of cells throughout the body.

  • Normal lymphoid stem cells give rise to different types of lymphocytes (a type of white blood cell) that protect us from infections, such as influenza and measles.
  • Myeloid stem cells give rise to neutrophils (a type of white blood cell) that protects us from bacterial infections.


Platelets (also called thrombocytes) help to stop bleeding.


Plasma is the clear, light yellow fluid the body uses to carry different blood cells throughout the body. It is made up of water, salt and proteins.

What are the different types of leukemia in children?

Leukemia in children can be acute (the cancer cells grow quickly) or chronic (the cancer cells grow slowly). Most types of leukemia in children are acute.


  • Acute lymphocytic leukemia (ALL) is the most common type of leukemia in children. It is also called acute lymphoblastic leukemia. In children with ALL, their bodies make too many lymphoblasts (immature lymphocyte cells).
  • Acute myelogenous leukemia (AML) is the second most common type of leukemia in children. This is when the body makes too many immature myeloid blasts (immature myeloid cells).
  • Hybrid or mixed lineage leukemia is a rare type of leukemia in which a child has both ALL and AML.


  • Chronic myelogenous leukemia (CML). This type is rare in children. It causes the body to make too many myeloid cells (different types of white blood cells, including neutrophils and the cells that develop into neutrophils, such as myelocytes and others).
  • Chronic lymphocytic leukemia (CLL). This type is almost never seen in children. CLL causes the body to make too many lymphocytes.
  • Juvenile myelomonocytic leukemia (JMML). This is a rare leukemia that typically presents in the first year of life with an elevated (higher than usual) white blood cell count, low platelets, and an enlarged spleen (an organ near the stomach that helps control levels of different blood cells). Over time, myeloid blast cells crowd out the normal blood cells in the bone marrow.

What are the symptoms of leukemia in children?

Symptoms depend on how the leukemia cells have prevented normal blood cell production. Symptoms can also mimic other medical conditions. If you are worried or have questions about your child’s symptoms, ask the care team.

Symptoms of leukemia can include:

  • Pale skin
  • Easy bruising or bleeding (such as nosebleeds or bleeding gums)
  • Feeling tired, weak or cold more often than usual
  • Frequent or long-lasting infections
  • Fever
  • Headaches or dizziness
  • Poor appetite or weight loss
  • Shortness of breath
  • Pain in the bones or joints
  • Sudden swelling of the abdomen (belly area) or lymph nodes (bead-shaped groups of cells that help fight infections and illness, found in the neck, underarms, chest and groin)

iHead of the Pediatric Oncology service of the Hospital Juárez de México (HJM), Gabriel Peñaloza González
iiiMinistry of Health
ivColombian Fund for High Cost Diseases

Rev. 1/2021. Rev. 1/2021. Mass General for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so that you can be better informed. It is not a substitute for medical advice and should not be used to treatment of any medical conditions.