Common haematology terms and abnormalities

Common haematology terms and abnormalities

Anisocytosis Anisocytosis means that the red cells are of unequal size. It is a feature of many anaemias, and other blood conditions, and does not have much diagnostic value. The 'red cell distribution width' (RDW) is a quantitative measure of the degree of anisocytosis. The RDW is useful in the differential diagnosis of microcytic anaemia Acanthocytes Acanthocytes (also known as "spur cells") may be described as red cells with finger-like projections - typically 5-10 irregular, blunt projections (which vary in width, length and surface distribution and should not be confused with echinocytes). These cells have a decreased survival time and may be observed in liver disorders, increased blood cholesterol content or from the presence of abnormal plasma lipoprotein composition . Dohle bodies Dohle bodies appear as single or multiple light blue or grey staining areas in the cytoplasm of a neutrophil. They are rough endoplasmic reticulum containing ribonucleic acid (RNA) and may represent localised failure of the cytoplasm to mature. Dohle bodies are found in infections, poisoning, burns, and following chemotherapy. Echinocytes Echinocytes (also called "crenated cells") are morphologically altered red blood cells that appear to have numerous, fine, uniform spicules throughout the cell membrane. Echinocytes are often overlooked as an artifact of preparation e.g. due to storage or slow drying bloodsmears, however several disease processes (e.g. lymphosarcoma (partially as a result of chemotherapy), pk deficiency, uremia) and toxins have been found to alter the red blood cell membrane which leads to the formation of echinocytes. Haemobartonellosis Feline infectious anaemia (FIA) also known as Mycoplasma felis The most common red cell parasite in the UK is Haemobartonella felis which is a gram negative epicellular parasite found in feline erythrocytes. Red blood cell destruction is due primarily to immune-mediated events and direct injury to red blood cells induced by the organism is minimal. The attachment of the organism to erythrocytes commonly leads to the development of antibodies against the organism as well as to erythrocyte antigens so positive Coomb's tests are common. Clinically haemobartonellosis and primary immune haemolytic anaemia are difficult to differentiate. For the diagnosis of both these conditions an EDTA sample and fresh air dried blood film are required. Howell Jolly Bodies Howell-Jolly bodies are round, purple staining nuclear fragments of DNA in the red blood cell. They are usually observed singly in haemolytic anaemia, following splenectomy, and in cases of splenic atrophy. Multiple Howell-Jolly bodies may be observed in cases of megaloblastic anaemia. Macrocytes Macrocytes are red cells with an increased size, 9-12µm in diameter. They may be found in liver disease and megaloblastic anaemia, when associated with vitamin B12 or folic acid deficiency, the macrocytes may appear slightly oval in shape. Normochromic Normochromic describes the red cells as being of normal colour i.e. indication of haemoglobin content, for the species Normocytic Normocytic describes the red cells as being of normal size i.e. diameter for the species. Poikilocytosis Poikilocytosis is a term which indicates that red cells of abnormal shape are present on the blood film. Of itself it is fairly non-specific. Some particular types of poikilocyte are very informative, however. The 'tear-drop' poikilocyte is a characteristic feature of marrow fibrosis, but it can also be seen in other conditions. Schistocytes Schistocytes are red blood cell fragments that result from membrane damage encountered during passage through vessels. They occur in microangiopathic haemolytic anaemia, severe burns, uremia, and haemolytic anemias cause by physical agents, as in disseminated intravascular coagulation (DIC). They are sometimes referred to as "bite cells". Spherocytes Spherocytes are red cells which are almost spherical in shape. They are not biconcave like a normal red blood cell and do not have the central area of pallor which a normal red cell shows. These cells are associated with haemolytic anaemia