| Reticulocyte identification Reticulocytes are red blood cells prematurely released from the bone marrow. On a Wright-Giemsa stained blood smear, they appear as polychromatic macrocytes. Their presence in the peripheral blood may suggest hemolysis or bleeding. Their presence is expressed as a percentage of the red cell count: newly born= 3-7%; up to one week of age=1-3%; >one week =0.3-1.8%. Automated or manual methods may be used to enumerate reticulocytes. In clinical context, retics must be separated from debris, precipated stain, Pappenheimer bodies, Howell-Jolly bodies, and Heinz bodies. | View Page |
| Hemolytic disease of the newborn Jaundice was recognized in a day-old infant. Notice particularly the size variation (anisocytosis) of the erythrocytes on the infant's peripheral smear. What does this observation mean? Does it provide immediate information that might serve as guidance in expediting diagnosis and treatment? Note that normal-sized red blood cells, microcytes, microspherocytes, macrocytes, and nucleated red blood cells are all present. Red cell variations are expected findings in healthy neonates, but the variations here are exaggerated. Hyposplenic functional features may appear, including acanthocytes, spherocytes, and possibly Howell-Jolly bodies, especially if hemolysis is particularly vigorous. A high (3-7%) reticulocyte count is not unusual during the first three or four days after birth, however, the marrow in this jaundiced infant is proliferating vigorously in response to hemolysis. A call for more red cells is urgent. Immature red cells (in the form of nucleated red cells) and red cells with stippling of RNA (basophilic stippling) are readily identified. Red cell maturation sequence has not been totally processed in the marrow nor is all residual red cell debris removed by the spleen. In the lower photograph are reticulocytes stained by supravital stain (new methylene blue). Basophilic stippling (specks of RNA) stains with both supravital stains and with routine Wright-Giemsa stain. | View Page |
| Spherocytes and reticulocytes The photograph represents peripheral blood smear findings in another patient with hereditary spherocytosis. The red cells vary in size (anisocytosis)with a mixture of microcytes (red cells with central pallor) and microspherocytes (red cells with central staining). Macrocytes are conspicuous, some staining light blue. They are immature erythrocytes (reticulocytes)released from the bone marrow early. The bone marrow, geared up for rapid cell release in response to severe hemolysis, expels young red blood cells into the circulation before completing their 24 hour maturation cycle. Hemolysis, jaundice, and gall stone formation disappear following splenectomy. Gallbladder and stone removal eliminate the right upper quadrant pain. A serious consideration, especially in children with hereditary spherocytosis, is hemolytic crisis. A viral infection may allow red blood cell destruction to continue unabated. Anemia of such sudden onset and severity may become catastrophic, with death as the outcome. Splenectomy removes this possibility. | View Page |
| Warm antibody hemolytic disease A 49-year-old male with pneumonia was treated with penicillin. He became jaundiced with yellow sclera. Observe the photograph of his peripheral blood smear. Anisocytosis was observed with pale-centered microcytes and polychromatophilic macrocytes. Since penicillin is a classic offender for autoimmune hemolytic disease, the clinician asked for an antihuman globulin (AHG) test, also known as the Coombs test. A positive AHG reaction occurs when the antibody stimulated by penicillin becomes attached to red blood cells. Hemolysis follows, leaving the patient with jaundice and a peripheral blood smear, as demonstrated in the photograph. | View Page |
| A 10-year-old child presents with jaundice and scleral icterus. The photograph captures a section of the peripheral blood smear. The report should direct attention to: | View Page |
| Considering the predominance of microspherocytes on the blood smear, and the patient's jaundiced condition, what is the most likely diagnosis? | View Page |
| Conditions suggested by the macrocytes and the neutrophil in the photograph to the right include: | View Page |
| The arrow on this photomicrograh points to a macrocyte. The oval shape should be noted on the patient report. | View Page |
| Poikylocytosis and Basophilic Stippling Poikylocytosis that includes tear-drop shaped erythrocytes, schistocytes, and target cells is present in both the upper and lower photographs. In addition, macrocytes are present, two of which (one in each field) have coarse basophilic stippling. The stippling may represent abnormal hemoglobin synthesis. These stippled erythrocytes remain in circulation in the absence of pitting by a spleen. | View Page |
| Hypersegmented Neutrophils The focus of these photographed fields is on the occasional large oval macrocyte,and the large, hypersegmented neutrophils representing either vitamin B-12 or folic acid deficiency, or both. The distinct hypochromia of many of the erythrocytes reflects low iron stores. | View Page |
| Using the lymphocyte as a guideline, the two cells below the lymph and in the center would be described as: | View Page |
| Pseudomacrocytes Another type of macrocyte can be seen in the center of this slide. Notice it appears larger than the lymphocyte but in contrast to megalocytes has an area of central pallor. These macrocytes are sometimes referred to as "pseudo macrocytes," since their size is the result of exaggerated flattening (leptocyte) and thus the presence of the central pallor. The MCV for this type of macrocyte is within normal range. Pseudomacrocytes can be seen in patients with cirrhosis of the liver, obstructive jaundice, post splenectomy and conditions that affect the red cell membrane. | View Page |
| Pseudomacrocytes Pseudo macrocytes, as well as some microcytes, can be seen in this slide. Notice that pseudomacrocytes do not have the oval appearance seen in some megalocytes. | View Page |
| The round and oval red cells with diameters of greater than 9 microns and decreased central pallor seen in this slide are example of: | View Page |
| The cell in the center of this slide would be a: | View Page |
| Another Example of Macrocytosis Another example of macrocytes is seen in this slide. This patient had pernicious anemia, which results from an inability to absorb the vitamin B12 needed for DNA synthesis. Since many cells are destroyed in the bone marrow, decreased numbers of red cells are present in the circulating blood causing low hemoglobin(anemia).
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| Summary of Macrocytes To summarize, two types of macrocytes can be seen, true macrocytes (megalocytes) and pseudomacrocytes. The MCV and MCH values will be increased when megalocytes are present, while all the indice values will be normal when pseudomacrocytes are found. | View Page |
| Megalocytes (macrocytes) are characterized by: (Choose ALL of the correct answers) | View Page |
| Size Variation Red blood cells can vary in size (diameter/volume) from smaller than normal, microcytes, to larger than normal, macrocytes. When red cells of normal size, microcytes and macrocytes are present in the same field, the term anisocytosis is used.Since the purpose of this unit is to acquaint you with the appearance (identification) of abnormal red cell morphology, percentages of abnormalities present will not be considered. It is important to be aware that rating red cell morphology for the purpose of reporting it is a skill which must be learned before you are able to complete this aspect of a differential count. | View Page |
| Macrocytes Macrocytes have a diameter of 9-14 microns (1 1/2 to 2 times larger than normal red cells) and the MCV is 100 cubic microns or more. The macrocytes seen in this slide are referred to as true macrocytes, or megalocytes. Compare the red cells in the field to the nucleus of the lymphocyte in the lower left. Many of the red cells in the field are larger than the lymphocyte and have little or no central pallor. As a point of reference, the cells just below and above the lymphocyte are macrocytes. Megalocytes are frequently oval and several examples of oval macrocytes can be seen in this field. Megalocytes are the result of decreased deoxyribonucleic acid (DNA) synthesis, frequently due to vitamin B12 and/or folic acid deficiencies. Decreased DNA synthesis causes the nucleus in the developing red cells to mature at a slower than normal rate. Since hemoglobin production is not affected, the mature red cell is larger than normal is filled with hemoglobin.
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| Color of Erythrocytes In addition to the amount of hemoglobin present, the color of the cell must also be considered. Completely mature red cells appear buff-colored, while slightly immature non-nucleated red cells (reticulocyte stage) appear blue/gray on Wright's stained smears due to the presence of residual ribonucleic acid (RNA).The terms used to describe these cells are polychromasia or polychromatophilia. Polychromatophilic cells are frequently larger in size than mature red cells and can be distinguished from both types of macrocytes by this distinctive color.
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| Hypochromia and Hyperchromia defined A decreased amount of hemoglobin is referred to as hypochromasia or hypochromia. MCHC values of 30% or less reflect this condition. Hyperchromasia and hyperchromia, refer to a hypothetical situation rather than an actual occurrence. The word, hyperchromia/sia, means increase in color; however the MCHC value cannot be higher than 36, since it is impossible for a cell to contain "too much" hemoglobin.Cells located in the "too thin" portion of the smear often appear to be "hyperchromic". Megalocytes (macrocytes), which appear to have increased amounts of hemoglobin, have an MCHC value within normal limits, indicating that the cells, although larger than normal, are normochromic. | View Page |