Here you will find definitions and meanings of some of the most frequently used terms on the site.
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A decrease below normal in the concentration of the three major blood cell types: red cells, white cells and platelets.
A medical doctor who identifies disease by studying tissues under a microscope. See Haematopathologist.
A sample of blood placed on a slide and dyed so that the cells can be examined under a microscope.
A long, thin, flexible tube that is inserted into the body and used to administer medications, antibiotics, fluids and nutrition for an extended period of time. It can also be used to obtain blood samples. Prior to insertion of the PICC, the patient is given a local anaesthetic to numb the arm between the elbow and the shoulder. The PICC is inserted through the skin into a vein in the arm and advanced until it reaches the superior vena cava just above the heart. The superior vena cava is one of the veins in the central venous system. The PICC can be maintained for several weeks to months, eliminating the need for standard intravenous (IV) administration.
Pinhead-sized sites of bleeding in the skin. This type of bleeding results from a very low platelet count. The small punctate (spotted; marked with points or punctures) haemorrhages are frequently seen on the legs, feet, trunk and arms. They evolve from red to brown and eventually disappear. They stop developing when the platelet count increases.
Cells that readily eat (ingest) microorganisms such as bacteria and fungi and kill them as a means of protecting the body against infection. The two principal phagocytes are neutrophils and monocytes. They leave the blood and enter tissues in which an infection has developed. A severe decrease in the concentration of these cells is the principal cause of susceptibility to infection in patients treated with intensive radiation therapy and/or chemotherapy. Treatment may suppress blood cell production in the marrow, resulting in deficiencies of these phagocytic cells.
The liquid portion of the blood, in which the blood cells, platelets, proteins and various other components are suspended. It is also referred to as “blood plasma.”
Transfusion of donor platelets, which may be needed to support some patients treated for blood cancer. The platelets can be gathered from several unrelated donors and given as pooled, random-donor platelets. The platelets from about six single-unit blood donors are required to significantly raise the platelet count in a recipient. Sufficient platelets can be obtained from one donor by a procedure known as “apheresis.” This technique skims the platelets from large volumes of blood as it passes through the apheresis machine. The red cells and plasma are returned to the donor. The advantage of single-donor platelets is that the patient is not exposed to the different antigens on platelets from many different people and thus is less likely to develop antibodies against donor platelets. HLA-matched platelet transfusion can be given from a related donor who has an identical or very similar HLA tissue type.
Small blood cells (about one-tenth the volume of red cells) that stick to the site of blood vessel injury aggregate and then seal off the injured blood vessel to stop bleeding. “Thrombocyte” is another name for platelet and is often used as the prefix in terms describing disorders of platelets, such as thrombocytopenia (too few) or thrombocythemia (too many).
A technique to expand trace amounts of DNA or RNA so that the specific type of the DNA or RNAcan be determined or studied. This technique has become useful in detecting a very low concentration of residual blood cancer cells, too few to be seen using a microscope. PCR can detect the presence of one blood cancer cell among 500,000 to 1 million blood cells. PCR requires a specific DNA (or RNA) abnormality or marker, like an oncogene, in the leukaemia or lymphoma cells in order to be used for identifying residual abnormal cells.
A port is a small device that is used with a central line to access a vein. The port is placed under the skin of the chest. To take blood samples (or to give medicines or nutrition) the doctor or nurse puts a needle through the skin into the port. A numbing cream can be put on the skin before the port is used.
A cell of the marrow that is very early in development along the pathway to myeloid cells. It represents the next stage after the blast cell stage.