Uncontrolled production of WBCs can be caused by can cerous mutation of a myelogenous or lymphogenous cell. This process causes leukemia, which is usually characterized by greatly increased numbers of abnormal WBCs in the circulating blood.
Two General Types of Leukemia: Lymphocytic and Myelogenous. The lymphocytic leukemias are caused by cancerous production of lymphoid cells, usually beginning in a lymph node or other lymphocytic tissue and spreading to other areas of the body. The second type of leukemia, myelogenous leukemia, begins by can cerous production of young myelogenous cells in the bone marrow and then spreads throughout the body so that WBCs are produced in many extramedullary tissues—especially in the lymph nodes, spleen, and liver.
In myelogenous leukemia, the cancerous process occasionally produces partially differentiated cells, resulting in what might be called neutrophilic leukemia, eosinophilic leukemia, basophilic leukemia, or monocytic leukemia. More frequently, however, the leukemia cells are bizarre and undifferentiated and not identical to any of the normal WBCs. Usually, the more undifferentiated the cell, the more acute is the leukemia, often leading to death within a few months if untreated. With some of the more differentiated cells, the process can be chronic, sometimes developing slowly over 10 to 20 years. Leukemic cells, especially the very undifferentiated cells, are usually nonfunctional for providing normal protection against infection.
EFFECTS OF LEUKEMIA ON THE BODY
The first effect of leukemia is metastatic growth of leukemic cells in abnormal areas of the body. Leukemic cells from the bone marrow may reproduce so greatly that they invade the surrounding bone, causing pain and, eventually, a tendency for bones to fracture easily.
Almost all leukemias eventually spread to the spleen, lymph nodes, liver, and other vascular regions, regardless of whether the origin of the leukemia is in the bone marrow or the lymph nodes. Common effects in leukemia are the development of infection, severe anemia, and a bleeding tendency caused by thrombocytopenia (lack of platelets). These effects result mainly from displacement of the normal bone marrow and lymphoid cells by the nonfunctional leukemic cells.
Finally, an important effect of leukemia on the body is excessive use of metabolic substrates by the growing can cerous cells. The leukemic tissues reproduce new cells so rapidly that tremendous demands are made on the body reserves for foodstuffs, specific amino acids, and vita mins. Consequently, the energy of the patient is greatly depleted, and excessive utilization of amino acids by the leukemic cells causes especially rapid deterioration of the normal protein tissues of the body. Thus, while the leukemic tissues grow, other tissues become debilitated. After metabolic starvation has continued long enough, this factor alone is sufficient to cause death.
