| The M:E ratio represent the ratio of nucleated bone marrow cells with respect to: | View Page |
| Match each of the following: | View Page |
| Preparation of Concentrated Smears In some laboratories the anticoagulated sample is used to prepare concentrated smears. Placing the fluid in a Wintrobe tube and centrifuging it separates the sample into four layers:fat and perivascular cellsplasmabuffy layer - myeloid and nucleated erythroid cellserythrocytesThe volume of each layer is measured using the scale on the Wintrobe tube and then the percentage of each layer is calculated. Next the plasma is removed and a smear is made from the buffy coat and top of the red cell layer. Either the manual push method or cytospin technique may be used to make the smears. They may be stained with a variety of cytochemical stains. Concentrated smears are used to examine cell morphology and demonstrate the presence of abnormal cells when the marrow is hypocellular. The smears cannot be used for differential counts or evaluation of cellularity. | View Page |
| Changes in Cell Distribution Changes in the distribution of cells in the marrow are most apparent in the first month of life. At birth, granulocyte cells predominate. The myeloid to erythroid (M:E) ratio is somewhat higher in newborns and during infancy than it is later on in childhood and in adults. | View Page |
| Examination of Wright-Giemsa Stained Bone Marrow Examination of Wright-Giemsa stained bone marrow preparation involves examination under low power (10X objective) high power (40-50X objective )and oil immersion (100X objective). Low power examination: Assess quality of smear, assess number of megakaryocytes.Assess myeloid to erythroid ratio.Evaluate morphology and do differential count. | View Page |
| Low Power Magnification This smear is shown under low power (10x objective) magnification. The reddish cells in the background are mature red blood cells. The dark dots are nucleated erythroid and myeloid precursors. The large dark dot in the middle is a megakaryocyte. Normally, about 5 to 10 megakaryocytes are seen per microscopic field at low power magnification. Clusters of megakaryocytes usually indicate megakaryocytic hyperplasia. Less than 2 megakaryocytes per low power field may mean megakaryocytic hypoplasia. | View Page |
| Normal M:E Ratio The normal M:E ratio in adults varies from 1.2:1 to 5:1 myeloid cells to nucleated erythroid cells. An increased M:E ratio (6:1) may be seen in infection, chronic myelogenous leukemia or erythroid hypoplasia. A decreased M:E ratio (<1.2-1) may mean a decrease in granulocytes or an increase in erythroid cells. M:E ratios are somewhat higher in newborns and infancy than in later childhood and in adults. It is important to note that lymphocytes, monocytes and plasma cells are not included in the M:E ratio. | View Page |
| Percentages of Myeloid and Erythroid Precursors The normal cellularity has been described as 50%. Therefore, about 40% of the cells would be myeloid (granulocytic) and 10% erythroid. Since cellularity and distribution may vary from one area of the marrow to another, an acceptable range for percentages of myeloid and erythroid cells would be:Myeloid cells 25-55%Erythroid cells 8-14% | View Page |
| Normal M:E Ratio A normal M:E ratio is depicted in this slide. Notice that the area shown is a portion of the slide near a particle or spicule of marrow where the cells are numerous. The morphology can still be clearly differentiated. The small dark cells scattered throughout the slide are erythroid cells, while the larger, lighter staining cells are myeloid cells. The normal M:E ratio varies from 1.2 to 5 myeloid cells for each erythroid cell. | View Page |
| Differentiating Myeloid from Erythroid Cells To help you learn to differentiate myeloid cells and erythrocytes under high power, some slides showing thinner areas than would normally be used for determination of the M:E ratio have been included. Erythroid cells are shown at the arrows. | View Page |
| Increased M:E Ratio An increased M:E ratio is present in this field. Many more myeloid cells are present than erythroid cells. The M:E ratio is approximately 25:1. | View Page |
| Decreased M:E Ratio An example of a decreased M:E ratio in a thin area of the smear. A decreased M:E ratio means that the myeloid cells are decreased in number when compared to the erythroid cells. Approximate ratio is 1:2. | View Page |
| Estimating Myeloid to Erythroid Ratio When examining a bone marrow smear, estimate the M:E ratio for each of ten fields and take the average as the estimated M:E ratio. | View Page |
| Representative Counting Field The actual cell count is performed using the oil (100x) objective. This oil immersion field shows a representative counting field. Four granulocytes, a prorubricyte, and two rubricytes are completely visible here. 100 to 500 nucleated cells are generally counted,depending on the cellularity of the smear, and only cells completely visible in the field should be included in the count. | View Page |
| High Power Examination High power (40x objective) examination can be used to estimate the myeloid-to-erythroid ratio. The erythrocytes are nucleated, immature erythrocytes. Under high power, nucleated red cells appear to have a dark purple nucleus as opposed to the lighter staining nucleus of the myeloid or granulocyte series. Lymphocytes also have a dark staining nucleus and some may be erroneously included in the erythroid estimate. In the normal marrow these numbers are insignificant. | View Page |
| Auer Rods Auer rods are red staining, needle-like bodies seen in the cytoplasm of myeloblasts, and/or progranulocytes in leukemia.
Auer rods are cytoplasmic inclusions which result from an abnormal fusion of the primary (azurophilic) granules. Single or multiple Auer rods may be seen in the cytoplasm of a cell. If more than one is present, they are frequently close together and may even be overlapping.
Their identification is very important because, if found, they can confirm the presence of myeloblasts indicating the presence of a myeloid (non-lymphoblastic) leukemia. They can also be seen in myeloid blast crisis in chronic granulocytic leukemia. Auer rods are never seen in lymphoblasts. This differentiation is important because the treatment of lymphoblastic and myeloblastic leukemia are different.
Auer Rods always classified as pathological. | View Page |
| Toxic Granulation Toxic granulation is manifested by the presence of large granules in the cytoplasm of segmented and band neutrophils in the peripheral blood. The color of these granules can range from dark purplish blue to an almost red appearance.
Toxic granules are azurophilic granules normally present in early myeloid forms, but which are not normally seen at the band and segmented stages of neutrophil maturation. These granules contain peroxidases and hydrolases.
Toxic granulation is seen in cases of severe infection, as a result of denatured proteins in rheumatoid arthritis or, less frequently, as a result of autophagocytosis. Infection is the most frequent cause of toxic granulation.
This type of granulation may be seen in cells which also contain Dohle bodies and/or vacuoles. Cells containing toxic granules may have decreased numbers of specific granules.
Cells containing only a few specific granules, with or without toxic granules, are said to be degranulated. The nucleus in degranulated cells may often be round-bilobed, smooth and pyknotic. This type of nucleus is the result of aging and will disintegrate soon.
Increased basophilia of azurophilic granules simulating toxic granules may occur in normal cells with prolonged staining time or decreased pH of the stain. | View Page |
| The cells included in the composite image were found in a peripheral blood smear with a total WBC of 24,500/mm3. The differential count was:
myelocytes 1
metamyelocytes 4
band neutrophils 15
segmented neutrophils 40
monocytes 8
eosinophils 2
basophils 1
lymphocytes 29.
This hematologic picture is most consistent with: | View Page |
| Normal Bone Marrow Cells A normal bone marrow smear stained with Wright/Giemsa stain is captured in this photograph.Note the normal maturation sequence beginning with myelocytes (the two large cells in the left upper corner)through metamyelocytes, band neutrophils,and multi-lobed segmented neutrophils.The small cells with darkly staining, centrally placed nuclei are normoblasts (three are clustered in the left lower field).Absent in this field are eosinophils, basophils and megakaryocytes.A normal M:E ratio of 2.4:1 is calculated from the twelve myeloid cells and five normoblasts. Two lymphocytes are identified, one left center, the other left upper. | View Page |
| Normal Bone Marrow Illustrated in the photograph is a normal bone marrow smear stained with Wright/Giemsa stain. Note the evenly distributed cells with normal maturation in both the myeloid and erythroid maturation sequences.An estimation of the percentage composition of cells can be made by experienced observers from scanning of multiple fields. In some instances a detailed differential count of 300 or more cells must be made.In normal bone marrows, the myeloid to erythroid ratio (M:E ratio)ranges from 1.2:1 to 5:1.A ratio of less than 1.2:1 indicates depressed leukopoiesis or erythroid hyperplasia. Ratios of 6:1 or greater usually indicates infection, erythroid hypoplasia, or chronic myelogenous leukemia.An assessment of the overall cellularity is also useful. In general, cellularity of less than 25% indicates hypoplasia; greater than 75% indicates hyperplasia. | View Page |
| The upper photograph of a bone marrow section reveals distinct hyperplasia with total replacement of marrow fat. A bone marrow smear stained with Wright/Giemsa is displayed in the lower photograph. Calculate the M:E ratio between myeloid and erythroid cells found in the lower photograph. The total peripheral blood white blood cell count was 5,400/cumm. This bone marrow architecture may be found in each of the following conditions except: | View Page |
| The upper photograph of this bone marrow section also reveals distinct hyperplasia with total replacement of the fat. The lower photograph is a Wright/Giemsa stain. Calculate the M:E ratio of the distribution of myeloid and erythroid cells in the lower photograph. The peripheral white blood count was 18,500/cumm. The most likely associated condition is: | View Page |
| Additional comments on this exercise The following pages in this presentation includes a series of white blood cell abnormalities that may be identified in a peripheral blood smear. Many of the cases will simulate the practice of a peripheral smear review by a hematology morphologist. He/she must asses what responses in patient care may be triggered by the clinician attempting to interpret the reported findings on a peripheral smearObservations of white blood cell abnormalities in the peripheral blood smear should be reported so as to direct the physician to an immediate specific diagnosis, such as: (1) atypical lymphocytes suggesting infectious mononucleosis rather than leukemia, (2) toxic granules in neutrophils as in acute infections, or atypical granules suggesting a genetic disorder, (3) an unusual mix of cells, such as too many or too few neutrophils, monocytes, or other myeloid cells, and (4) the presence of giant platelets, myelocytes, or other cells suggesting a myelodysplastic syndrome.In summary, laboratory data should be presented to clinicians in a user friendly way to promote effective decision making. The design of the data base of information must be directed toward providing clinically helpful information clearly and quickly in order to facilitate appropriate action in terms of optimizing patient care outcomes.d | View Page |
| A peripheral blood smear with many myeloid cells (photograph) was presented for morphology review. Toxic vacuoles in the neutrophil and monocyte most likely represent: | View Page |