Leukaemia

Any of several types of cancer in which there is a disorganized proliferation of white blood cells within the bone marrow. Organs such as the liver, spleen, lymph nodes, or brain may cease to function properly if they become infiltrated by abnormal cells. Leukaemias are classified into acute and chronic types (acute types generally develop faster than chronic leukaemia). They are also classified according to the type of white cell that is proliferating abnormally. If the abnormal cells are lymphocytes or lymphoblasts (precursors of lymphocytes), the leukaemia is called lymphocytic or lymphoblastic leukaemia. If abnormal cells are derived from other types of white cell or their precursors, the disease is called myeloid, myeloblastic, or granulocytic leukaemia. (See also leukaemia, acute; leukaemia, chronic lymphocytic; leukaemia, chronic myeloid.)