Acute leukemia is characterized by the abnormal proliferation of immature blood cells. The proliferation and accumulation of these cells in the bone marrow causes a cessation in the manufacturing of healthy cells. Eventually these undeveloped cells are released into the blood and spread to the organs. This form of leukemia is the most common in children.
Chronic Leukemia is distinguished by the increased accumulation of abnormal mature white blood cells. The progression takes months or years but eventually their numbers overtake those of normal blood cells. This form usually occurs in older people.
It can be classified further into 5 subtypes of which 3 occur in children. Acute Lymphoblastic Leukemia or ALL is the common form of leukemia in children often called acute childhood leukemia. This accounts for 80-85% of all leukemias in childhood. Then there is Acute myelegenous leukemia ir AML which is more common in adults than in children. It accounts for 15% of all leukemia cases. Finally the last is Chronic myelogenous leukemia or CML which develops in 5% of children.