Next to brain tumors, leukemia is highly mortal. It causes the most concerned and is a reason for long term hospitalization. Leukemia is simply cancer of the white blood cells or leukocytes. White blood cells (WBCs) are responsible for helping the body fight against infection. These cells are generated in the bone marrow. In a normal situation, there is no problem with WBC`s maturity, but in a leukemic tendency, WBCs becomes immature, enormous, and abnormal in quality and quantity. Leukemia (American English) or leukaemia (British English) indicates an abnormal increase of immature white blood cells called "blasts”. Rudolf Virchow in 1845 found leukemia for first time and he defined it in two terms: “Leukos” meaning "white” and “aima” meaning “blood" in Greek terminology. The nature of leukemic cells is destructive, and they tend to multiply at a different pace. There are four different types of leukemia based on the origin - whether it is from marrow or from lymphocytes. They are: Acute lymphocytic leukemia, Acute myeloid leukemia, Chronic lymphocytic leukemia, and Chronic myeloid leukemia.
Two major forms of leukemia are Acute and chronic. Acute leukemia is characterized by a rapid increase in the number of immature blood cells. Acute one is the most common form of leukemia in children. Chronic leukemia is characterized by excessive built-up of relatively mature, but still abnormal WBCs.