Leukemia is usually described either as "acute", which grows quickly, or "chronic", which grows slowly. The vast majority of<unk>  is acute, and chronic leukemias are more common in adults than in children. Acute leukemias typically develop and worsen quickly (over periods of days to weeks). Chronic leukemias develop over a slower period of time (months), but are more difficult to treat than acute leukemias. The following are some of the main types of leukemia that occur in children. Acute lymphoblastic The most common form<unk>  is acute lymphocytic (or lymphoblastic) leukemia (ALL), which makes up 75-80% of<unk>  diagnoses. ALL is a form of leukemia that affects lymphocytes, a type of white blood cells which fights infection. When a patient has ALL, the bone marrow makes too many immature white blood cells and they do not mature correctly. These white blood cells also do not work correctly to fight infection. The white blood cells overproduce, crowding the other blood cells in the bone marrow. Acute myelogenous Another type of acute leukemia is acute myelogenous leukemia (AML). AML accounts for most of the remaining cases of leukemia in children, comprising about 20% of<unk> . AML is cancer of the blood in which too many myeloblasts (immature white blood cells) are produced in the bone marrow. The marrow continues to produce abnormal cells that crowd the other blood cells and do not work properly to fight infection. Acute promyelocytic Acute promyelocytic leukemia (APL) is a specific type of AML. In this leukemia promyelocytes are produced and build up in the bone marrow. A specific chromosome translocation (a type of genetic change) is found in patients with APL. Genes on chromosome 15 change places with genes on chromosome 17. This genetic change prevents the promyelocytes from maturing properly. Chronic myelogenous Chronic myelogenous leukemia (CML) is a chronic leukemia that develops slowly, over months to years. CML is rare in children, but does occur. CML patients have too many immature white blood cells being produced, and the cells crowd the other healthy blood cells. A chromosome translocation occurs in patients with CML. Part of chromosome 9 breaks off and attaches itself to chromosome 22, facilitating exchange of genetic material between chromosomes 9 and 22. The rearrangement of the chromosomes changes the positions and functions of certain genes, which causes uncontrolled cell growth. Chronic lymphocytic leukemia (CLL) is another form of chronic leukemia, but is extremely rare in children. Juvenile myelomonocytic Juvenile myelomonocytic leukemia (JMML) is a form of leukemia in which myelomonocytic cells are overproduced. It is sometimes considered a myeloproliferative neoplasm. It is rare and most commonly occurs in children under the age of four. In JMML, the myelomonocytic cells produced by the bone marrow and invade the spleen, lungs, and intestines.
Childhood leukemia
Myeloid leukemia
Acute lymphoblastic leukemia
Lymphoid leukemia
Acute myeloid leukemia
Acute leukemia
B-cell leukemia
Chronic leukemia