Leukemia is cancer of the blood. It’s the most common form of cancer in childhood. The cancer cells grow in bone marrow and go into the blood. The bone marrow is the soft, spongy center of some bones. It makes blood cells. When a child has leukemia, the bone marrow makes abnormal blood cells that don’t mature. The abnormal cells are usually white blood cells (leukocytes). The bone marrow also makes fewer healthy cells. The abnormal cells reproduce very quickly. They don’t work the same as healthy cells. A child has symptoms when he or she has more abnormal cells and less normal cells.
The types of blood cells include:
- Red blood cells (erythrocytes). Red blood cells carry oxygen. When a child has a low level of healthy red blood cells, this is called anemia. A child may feel tired, weak, and short of breath.
- Platelets (thrombocytes). Platelets help with blood clotting and stop bleeding. When a child has low levels of platelets, he or she bruises and bleeds more easily.
- White blood cells (leukocytes). These fight infection and other disease. When a child has low levels of white blood cells, he or she is more likely to have infections. The types of leukocytes are:
- Lymphocytes. There are 2 types: B lymphocytes and T lymphocytes. These cells grow from lymphoblasts in the bone marrow.
- Granulocytes. There are 3 types: neutrophils, basophils, and eosinophils. These cells grow from myeloblasts in the bone marrow.
- Monocytes. These cells grow from monoblasts in the bone marrow.
There are different types of leukemia in children. Most types are either acute or chronic. Acute develops quickly, over days or weeks. Chronic develops more slowly, over months or years. Some of the types of leukemia that occur in children include:
- Acute lymphocytic (lymphoblastic) leukemia (ALL). This is the most common type of leukemia in children. It starts from the lymphoblasts, the cells that form lymphocytes in the bone marrow.
- Acute myelogenous (myeloid, myelocytic, non-lymphocytic) leukemia (AML). This is the second most common type of leukemia in children. It starts from the myeloblasts or myeloid cells that form many white blood cells, plus red blood cells and platelets.
- Hybrid or mixed lineage leukemia. This type is rare. It is a mix of ALL and AML.
- Chronic myelogenous leukemia (CML). This type is also rare in children. Like AML, it starts from the myeloblasts or myeloid cells that form many white blood cells, plus red blood cells and platelets.
- Chronic lymphocytic leukemia (CLL). This type is extremely rare in children. Like ALL, it starts from the lymphoblasts, the cells that grow lymphocytes in the bone marrow.
- Juvenile myelomonocytic leukemia (JMML). This is a rare type of cancer that doesn’t grow quickly (acute) or slowly (chronic). It also starts from myeloblasts or myeloid cells.
The symptoms depend on many factors. The cancer may be in the bone marrow, blood, and other tissue and organs. Other tissue and organs may be affected. These may include the lymph nodes, liver, spleen, thymus gland, brain, spinal cord, gums, and skin.
Symptoms can occur a bit differently in each child. They can include:
- Pale skin
- Feeling tired, weak, or cold
- Shortness of breath, trouble breathing
- Frequent or long-term infections
- Easy bruising or bleeding, such as nosebleeds or bleeding gums
- Bone or joint pain
- Belly (abdominal) swelling
- Poor appetite
- Weight loss
- Swollen lymph glands (nodes)
The symptoms of leukemia can be like other health conditions. Make sure your child sees a healthcare provider for a diagnosis.