Morphological Aspects of Blood Cells in Health and diseases PDF

Morphological Aspects of Blood Cells in Health and Diseases 1st Block Posting in Pathology Lecturer: Dr. Adeyemi  Outline Introduction Red Cell Morphology Morphology of Leucocytes Platelet Morphology Conclusion  Learning Goals To...

Morphological Aspects of Blood Cells in Health and Diseases 1st Block Posting in Pathology Lecturer: Dr. Adeyemi  Outline Introduction Red Cell Morphology Morphology of Leucocytes Platelet Morphology Conclusion  Learning Goals To be able to identify and describe the morphological features of normal erythrocytes, leucocytes, and platelets. To be able to determine the significance and diagnostic importance of morphologic changes seen in various conditions with respect to blood cells- erythrocytes, leucocytes, and platelets.  INTRODUCTION Determining a patient’s blood cell counts and examining the appearance of cells on a blood film is central to the diagnosis of blood cell diseases and can give important information about numerous other degenerative, inflammatory, and neoplastic diseases that are reflected in quantitative or qualitative changes of blood cells. The quantity and quality of blood cells reflects the aggregate function of the major blood forming tissue, the marrow, and is thus an essential component of diagnosis and follow up of primary haematological disorders.  RED CELL MORPHOLOGY In health, the red blood cells vary relatively little in size and shape. In well-spread, dried and stained films the great majority of cells have round, smooth contours and diameters within the comparatively narrow range of 6.0–8.5 um (appears to be about the same size as that of the nucleus of a small lymphocyte). The normal erythrocyte on a blood film is circular with central pallor. The MCV is a more sensitive measure of red cell volume than the red cell diameter  Normal Peripheral Smear The red cells are normocytic (normal Erythrocytes appear as circular, size) and normochromic (normal homogeneous disks of nearly uniform size, haemoglobin content) with normal ranging from 6–8 μm in diameter, with shape. central pallor not exceeding more than one third of the cell. On average, the red cells are approximately the same size as the nucleus of a small lymphocyte.  RED CELL MORPHOLOGY In disease, abnormality in the red cell picture stems from four main causes, which lead to characteristic cytological abnormalities. 1. Abnormal Erythropoiesis Anisocytosis is the term that describes variation in erythrocyte size, and is the morphologic correlate of the red cell distribution width (RDW). Macrocytes and microcytes are red cells larger or smaller than normal respectively. Their presence consistent with the measured MCV suggests certain diagnostic possibilities.  Mechanisms of red cell abnormalities and resultant cytological features CAUSE RESULTANT ABNORMALITY Attempts by the bone marrow to compensate Signs of less mature cells in the peripheral for anaemia by increased erythropoiesis blood (polychromasia and erythroblastaemia) Inadequate synthesis of haemoglobin Reduced or unequal haemoglobin content and concentration (hypochromia, anisochromasia or dimorphism) Abnormal erythropoiesis, which may be Increased variation in size (anisocytosis) and effective or ineffective shape (poikilocytosis), basophilic stippling, sometimes dimorphism Damage to, or changes affecting, the red cells Spherocytosis, irregular contraction, after leaving the bone marrow, including the elliptocytosis, ovalocytosis or fragmentation effects of reduced or absent splenic function (schistocytosis); the presence of Pappenheimer bodies, Howell–Jolly bodies and variable numbers of certain specific poikilocytes (target cells, acanthocytes and spherocytes)  Red Cell Morphology Poikilocytosis is a term used to describe variations in the shape of erythrocytes. The predominant appearance of a specific abnormality in red cell shape can be an important diagnostic clue in patients with anaemia. 2. Inadequate Haemoglobin Formation The normal erythrocyte appears as a disc with a rim of hemoglobin and a clear central area, which normally occupies less than one-half the cell diameter. Increased central pallor (hypochromia) is associated with disorders characterized by diminished haemoglobin synthesis, such as iron deficiency. Haemoglobin synthesis may also be impaired in chronic infections and other inflammatory conditions. A blood film of Iron deficiency anaemia. A blood film of Haemoglobin H disease. Shows a marked degree of hypochromia, microcytosis, marked anisocytosis and mild Shows microcytosis, moderate hypochromia, moderate anisocytosis poikilocytosis; there are some normally and some poikilocytes (including haemoglobinized cells. teardrop poikilocytes and red cell fragments). Some of the more frequent variations in size (anisocytosis) and shape (poikilocytosis) that may be found in different anaemias. DIC, disseminated intravascular coagulopathy; G6PD, glucose-6-phosphate dehydrogenase; HUS, haemolytic uraemic syndrome; TTP, thrombotic thrombocytopenic purpura.  Red Cell Morphology 3. Damage To Red Cells After Formation Spherocytosis Spherocytes are cells that are more spheroidal (i.e. less disclike) than normal red cells but maintain a regular outline. Causes – Genetic defects of the RBC membrane as in hereditary spherocytosis – Immune related- in delayed transfusion reactions, ABO haemolytic disease of the newborn, autoimmune haemolytic anaemia. – Action of bacterial toxins (e.g. Clostridium perfringens lecithinase A blood film of Hereditary A blood film of Autoimmune spherocytosis. Shows a moderate haemolytic anaemia. Shows marked spherocytosis and anisocytosis. degree of spherocytosis and There are numerous polychromatic anisocytosis. macrocytes  Red Cell Morphology Schistocytosis (Fragmentation) Schistocytes are smaller than normal red cells and of varying shape. Sometimes they have sharp angles or spines (spurs). – Sometimes they are round in contour, usually staining deeply but occasionally palely as the result of loss of haemoglobin at the time of fragmentation. Causes – Some genetic disorders (e.g. thalassaemias, congenital dyserythropoietic anaemia and hereditary pyropoikilocytosis – In acquired disorders e.g megaloblastic or dyserythropoietic anaemias – Effect of mechanical stresses e.g. microangiopathic haemolytic anaemias; and in cardiac haemolytic anaemias – Effect of direct thermal injury, e.g. severe burns  A blood film of Postcardiac A blood film of Microangiopathic surgery haemolytic anaemia. haemolytic anaemia. Shows numerous Shows numerous irregularly bizarrely shaped red cell fragments. shaped cell fragments  Red Cell Morphology Elliptocytosis and Ovalocytosis Elliptocytes are often present in large numbers in hereditary elliptocytosis. In hereditary pyropoikilocytosis, elliptocytes are only one of the many types of poikilocyte present. South-east Asian ovalocytosis is characterized by the presence of a variable number of elliptocytes, macro-ovalocytes and stomatocytes. They may also be seen in megaloblastic anaemia (macro-ovalocytes) and in iron deficiency anaemia (‘pencil cells’), in myelodysplastic syndromes and in primary myelofibrosis. The number of elliptocytes and teardrop poikilocytes has been observed to correlate with the severity of iron deficiency anaemia. A blood film of Hereditary elliptocytosis. Many of the cells are elliptical, and others are oval.  Acanthocytosis There are a small number of spicules of inconstant length, thickness and shape, irregularly disposed over the surface of the cell Causes Red cell membrane disorders e.g. abnormal phospholipid metabolism Post- splenectomy Hyposplenism Severe liver disease A blood film of Liver failure. Acanthocytes are conspicuous. Echinocytosis or crenation describes the A blood film of Normal blood process by which red after 24 h at 20C. Shows a marked cells develop numerous degree of crenation; also degenerative changes in white cells. short, regular projections from their surface. May be seen in Uraemia In premature infants after exchange transfusion or transfusion of normal red cells Artefactual  Red Cell Morphology Target Cells A cell in which there is a central round stained area and a peripheral rim of haemoglobinized cytoplasm separated by non-staining or more lightly staining cytoplasm. They result from cells having a surface that is disproportionately large compared with their volume. They may be normal in size, microcytic or macrocytic. Causes – Chronic liver diseases – Iron deficiency anaemia and in thalassaemia – Haemoglobinopathies e.g. haemoglobin C/b thalassaemia, haemoglobin C, E & H diseases, sickle cell anaemia, HbS/Beta thalassaemia. A blood film of Alcoholic liver A blood film of Haemoglobin C homozygosity. Shows numerous disease. Shows many target target cells and irregularly cells. contracted cells.  Red Cell Morphology Sickle Cells These are almost always present in films of freshly withdrawn blood of adults with homozygosity for haemoglobin S. However, sickle cells are usually absent in neonates and are rare in adult patients with a high haemoglobin F percentage. In films of fresh blood, the sickled cells vary in shape between boat-shaped forms and sickles. Target cells are also often a feature of blood films from patients with sickle cell anaemia  A blood film of Sickle cell A blood film of Sickle cell anaemia (homozygosity for haemoglobin S). Shows a anaemia (homozygosity for sickled cell, boat-shaped cells and a nucleated haemoglobin S). Shows boat-shaped red cell and target cells. cells and a nucleated red blood cell.  A blood film. Haemoglobin C disease Haemoglobin C (homozygosity for haemoglobin C). Shows many Crystals and SC targetcells, irregularly contracted cells and a Poikilocytes crystal of haemoglobinC. Sometimes it is apparent that haemoglobin C crystals are within otherwise empty red cell membranes. In patients with homozygosity for haemoglobin C, target cells and irregularly contracted cells are usually numerous and there may be occasional straight-edged haemoglobin C crystals, either apparently extracellularly or within the ghost of a red cell.  Erythrocyte Inclusions Howell–Jolly Bodies These are nuclear remnants. They are small, round cytoplasmic inclusions that stain purple on a Romanowsky stain. Causes – Post- splenectomy – splenic atrophy – Pernicious anaemia. – Coeliac disease Pappenheimer Bodies They are small peripherally sited basophilic (almost black) erythrocyte inclusions. They are composed of haemosiderin and their presence is related to sideroblastic erythropoiesis and hyposplenism A blood film of Post- A blood film of Autoimmune splenectomy. Shows thrombocytopenic purpura, postsplenectomy, showing a acanthocytes, a target cell and Pappenheimer body and a a Howell–Jolly body Howell–Jolly body. Red blood cell (RBC) inclusions which may be seen in the peripheral blood film in various conditions  Red Cell Morphology Rouleaux Formation Red blood cells (RBCs) appear as "stacked coins with cells overlapping each other. Stacked-coin morphology is noted throughout the peripheral blood smear. Causes : – Conditions associated with increased concentrations of globulins and/or fibrinogen – Hyperparaproteinemias – Waldenstrom macroglobulinemia – Multiple myeloma – Chronic inflammatory disorders Autoagglutination Clusters of RBCs due to antigen/antibody reactions in vivo Cannot distinguish the outlines of individual RBCs Causes: – Cold agglutinins (most often IgM antibodies) – Paroxysmal cold hemoglobinuria  Rouleaux and Autoagglutination Shows massive A blood film of Increased autoagglutination in a patient rouleaux formation in a patient with chronic cold with bacterial infection. haemagglutinin disease  Red Cell Morphology 4. Changes Associated With Compensatory Increase In Erythropoiesis Polychromasia It means red cells that stain shades of bluish grey. These cells are the reticulocytes Seen in conditions with intense erythropoietic drive e.g haemolytic anaemias (immune and non-immune), haemoglobinopathies, Extramedullary erythropoiesis, e.g. myelofibrosis or carcinomatosis. Absence of polychromasia is significant; – In a patient with severe anaemia it indicates that the bone marrow response is inadequate, e.g. in aplastic anaemia and pure red cell aplasia. Erythroblastaemia Erythroblasts may be found in the blood films of almost any patient with a severe anaemia; they are, however, very unusual in aplastic anaemia Conditions: – Haemolytic disease of the newborn – Cord blood of normal infants (small quantity) – Premature infants – Myelofibrosis – Carcinomatosis – Post- splenectomy – patients with sickle cell anaemia in painful crises. a blood film. Polychromasia. A blood film of b thalassaemia major with Some red cells stain shades of bluish inadequate blood transfusion support. There are grey. numerous erythroblasts; there are also hypochromic cells, target cells and a cell containing a Howell–Jolly body.  MORPHOLOGY OF LEUCOCYTES POLYMORPHONUCLEAR NEUTROPHILS In normal adults, neutrophils account for more than half the circulating leucocytes. They are the main defence of the body against pyogenic bacterial infections. Normal neutrophils are uniform in size, with an apparent diameter of about 13 mm on a film. They have a segmented nucleus and, when stained, pink/orange cytoplasm with fine granulation The majority of neutrophils have three nuclear segments (lobes) connected by tapering chromatin (clumped) strands. A blood film of Normal polymorphonuclear neutrophil and normal eosinophil Morphological Changes in Leucocytes Toxic granulation Is the term used to describe an increase in staining density and possibly number of granules that occurs regularly with bacterial infection and often with other causes of inflammation. It can also be a feature of administration of granulocyte colony stimulating factor (G-CSF) and of aplastic anaemia. Poorly staining (hypogranular) and agranular neutrophils occur in the myelodysplastic syndromes and in some forms of myeloid leukaemia  A blood film of Myelodysplastic A blood film of Severe infection. syndrome. Shows a hypogranular Neutrophils show toxic granulation. neutrophil and a normally granulated neutrophil. Morphological Changes in Leucocytes There are rare inherited disorders that are manifest by abnormal neutrophils. Alder–Reilly anomaly: The granules are very large, are discrete, stain deep red and may obscure the nucleus. Che´diak–Higashi syndrome: There are giant but scanty azurophilic granules, and the other leucocyte types may also be affected. Alder–Reilly neutrophils function normally, but in Che´diak–Higashi syndrome there is a functional defect that is manifested by susceptibility to severe infection. A blood film of Alder–Reilly Che´ diak– Higashi syndrome. anomaly. The nucleus is obscured Neutrophils show abnormal by the cytoplasmic granules granules  Morphological Changes in Leucocytes Nuclei With the three-lobed neutrophil as a marker, a shift to the left (less mature) or to the right (hypermature) can be recognized A left shift with band forms, metamyelocytes and perhaps occasional myelocytes is common in sepsis, when it is usually accompanied by toxic granulation. If promyelocytes and myeloblasts are also present, it is likely to be a feature of a leucoerythroblastic anaemia or leukaemia In very severe infections, ‘leukaemoid reaction’. A left shift, with a significant number of band forms, occurs normally in pregnancy. Stages of granulocyte maturation A blood film of Infection. A blood film of Chronic myeloid leukaemia. There is a left Shows left shift of the neutrophils shift with band forms, with toxic granulation. metamyelocytes, myelocytes and one myeloblast  Morphological Changes in Leucocytes Hypersegmentation The presence of hypersegmented neutrophils is an important diagnostic feature of megaloblastic anaemias. Neutrophil hypersegmentation can be defined as the presence of neutrophils with six or more lobes or the presence of more than 5% of neutrophils with at least five lobes. Other causes include: – Uraemia – iron deficiency – Cytotoxic treatment e.g.methotrexate. – Patients undergoing hydroxycarbamide or other drugs that induce megaloblastosis  Morphological Changes in Leucocytes Pelger–Huet Cells Is a benign inherited condition in which neutrophil nuclei fail to segment properly. The majority of circulating neutrophils have only two discrete equal-sized lobes connected by a thin chromatin bridge. The chromatin is coarsely clumped, and granule content is normal. A similar acquired morphologic anomaly, known as pseudo-Pelger cells may be seen in myelodysplastic syndromes, acute myeloid leukaemia with dysplastic maturation, and occasionally in chronic myeloid leukaemia  A blood film of Chronic A blood film of Pelger–Huet Myeloid leukaemia. There are five anomaly. Shows hypolobated ‘pseudo-Pelger’ cells; this abnormality is not seen in the neutrophils chronic phase of this disease.  Morphological Changes in Leucocytes Abnormal Neutrophil Inclusions Dohle bodies: These are light blue round or oval bodies approximately 1 to 2 μm in diameter, may be seen in the cytoplasm of neutrophils of patients with infections, burns, and other inflammatory states Inclusion bodies may also be seen in May- Hegglin anomaly Dohle bodies. These RNA remnants of May-Hegglin disease. The large rough endoplasmic reticulum appear as blue rod-shaped structures in blue-gray inclusions represent neutrophils involved in inflammatory precipitates of nonmuscle reactions myosin heavy chain type IIA.  EOSINOPHILS They are a little larger than neutrophils, 12–17 mm in diameter. They usually have two nuclear lobes or segments, and the cytoplasm is packed with distinctive spherical gold/orange (eosinophilic) granules. The underlying cytoplasm, which is usually obscured by the granules, is pale blue. Prolonged steroid administration causes eosinopenia. Moderate eosinophilia occurs in allergic conditions; More severe eosinophilia (20–50 109/l) may be seen in parasitic infections Greater numbers may be seen in other reactive eosinophilias such as T-cell lymphoma, B-cell lymphoma, acute lymphoblastic leukaemia, chronic myelogenous and occasionally so in acute myeloid leukaemia. eosinophilic leukaemia and the idiopathic hypereosinophilic syndrome. A blood film. Normal adult. Shows a basophil, an eosinophil A blood film of eosinophilia. and a neutrophil  BASOPHILS They are the rarest (