A high white blood cell count is associated with cancers of the blood-forming tissues, such as acute lymphocytic leukemia, acute myelogenous leukemia and chronic myelogenous leukemia, explains Mayo Clinic. Caused by an overproduction of immature blood cells that don't function properly, these cancers occur in both children and adults.
All leukemias develop in the bone marrow, the spongy tissue inside the bones that makes blood cells, states the American Cancer Society. In acute lymphocytic leukemia, the disease causes the bone marrow to produce too many immature lymphocytes, a type of white blood cell. These cells quickly spread from the bone marrow to the bloodstream, causing a measurable increase in the white blood cell count. They also spread to other parts of the body, such as the spleen, the lymph nodes, the testicles, the brain and the spinal cord.
Acute myelogenous leukemia, or myeloid leukemia, develops in a manner similar to acute lymphocytic leukemia, but it affects a different type of blood cell known as a myeloid cell, the American Cancer Society explains. Myeloid cells are precursors of other types of blood cells, including white blood cells (other than lymphocytes) red blood cells and platelets. As in acute lymphocytic leukemia, the immature myeloid cells take over the bone marrow and infiltrate the bloodstream, causing an increase in the number of circulating white blood cells.
Both lymphocytic and myeloid leukemias occur in acute and chronic forms. Acute leukemia progresses quickly, while chronic leukemia develops over a longer period of time, the American Cancer Society reports.