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Myeloid Information and Courses from MediaLab, Inc.

These are the MediaLab courses that cover Myeloid and links to relevant pages within the course.

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Body Fluid Differential Tutorial
Acute Myeloid Leukemia (AML)

This cytospin is from a patient diagnosed with Acute Myeloid Leukemia (AML) who had central nervous system involvement at the time of diagnosis.Notice the large size of these blasts. They have very fine, soft chromatin with very prominent multiple nucleoli. The cytoplasm has a hint of the background granularity that myeloid blasts have on a peripheral smear. These characteristics help to identify immature myeloid blast cells in fluid differential analysis.

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Acute Myeloid Leukemia (AML) continued

This cytospin shows three myeloid blasts (blue arrows) and a cell that is in mitosis (red arrow). These three blasts have varying amounts of cytoplasm and nuclear complexity, but all have similar chromatin /cytoplasmic textures and staining characteristics.Mitotic figures are not usually seen in benign fluids and should be commented upon in the differential report according to your hospital's protocols.

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Bone Marrow Aspiration Part I: Normal Hematopoiesis and Basic Interpretive Procedures
Bone marrow Differentials

For the clinical laboratory professionals who are only familiar with peripheral blood morphology, the first few observations of bone marrow aspirate smears can be overwhelming. The difference in cellularity between the two sample types, not to mention the wider variety of cell types, can lead to mental and visual overload. It is important to step back and break it down into more manageable pieces, starting on low power. Use low power (10x) to look at the distribution on the slide and the quality of the stain. Find areas where the spread/distribution of cells are thin enough (monolayer) to read easily and where you like the color balance and intensity of the stain. Next, add oil and move up to 50x and/or 100x power on the microscope.* Remember that there are several different cell types that are normally present and develop in the bone marrow before heading out into the peripheral blood. Most hematology technologists are familiar with the myeloid maturation sequence from peripheral differentials, even if immature cells are less commonly seen. However, there are additional cell types that are not seen on the peripheral blood differential, since they reside only in the bone marrow. Becoming more familiar with these cell types and the maturation sequences of the myeloid, erythroid, and megakaryocytic cells found in normal bone marrows will make performing these differentials less intimidating.One important concept to grasp is the continuum of cellular maturation sequences. There is no such thing as a magical switch that flips causing cells to jump to the next "textbook photo stage" as cell lines mature. Rather, each cell matures at its own pace. The maturation and morphology will vary from cell to cell and bone marrow to bone marrow. Understanding both nuclear and cytoplasmic normal morphology can aid in the identification of cells. *As counter-intuitive as it sounds for most applications, higher magnification does not always help with morphology. Reserve 100x for ultra fine detail.

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Calculating and Reporting the Myeloid:Erythroid (M:E) Ratio

Once the bone marrow cell count is completed and recorded, the M: E ratio should be assessed. This is performed by calculating the total myeloid precursors in proportion to the total erythroid precursors. Remember that this does not use the total white blood cell tally; the myeloid cells alone are counted, excluding lymphocytes, monocytes, macrophages, plasma cells, megakaryocytes, osteoclasts, osteoblasts, and other non-myeloid cells. In most circumstances, it is quite simple to divide the myeloid total by the erythroid total to find the ratio. This is always reported as a whole number ratio, and is normally around 3:1 (reference range= 2:1 to 4:1). In some situations where the erythroid portion is increased, or the myeloid series is decreased, the M:E ratio is reversed. This would still be expressed as a whole number ratio (example: 1:2). A simple way to perform the calculation is to always divide the larger value by the smaller. Which side of the colon, the 1 is placed on, is dependent on which cell type was larger. The 1 always belongs on the side of the cell type found in lower numbers.For example:Myeloid total 120 : Erythroid total 40 M:E ratio = 120 ÷ 40 = 3 or 3:1 So, the M:E ratio is 3:1Another example:Myeloid total 30 : Erythroid total 150Divide the larger number by the smaller (notice that the placement is reversed).150 ÷ 30 = 5 So, the M:E ratio is 1:5

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Under normal circumstances, the segmented neutrophil is the most common nucleated cell in the peripheral blood. These bacterial-infection-fighting cells are produced in the bone marrow and arise from their precursor cell, the myeloblast. The myeloblast is the youngest cell in the myeloid lineage. It is approximately 12-20 microns in size with very basophilic cytoplasm. The nucleus takes up around 2/3 of the total cell volume with a soft, finely stranded chromatin with very little clumping. The nucleus is eccentrically placed and ovoid, but can also be slightly flattened. Myeloblasts will typically have two or more nucleoli with well defined nucleolar membranes. In a well-stained preparation, you should be able to observe the outline and blue color of the nucleoli.The myeloblast's cytoplasm is basophilic and can have a hint of background "ground glass" graininess. This graininess is separate from any primary granules that develop as the cell progresses toward the progranulocyte stage. The cytoplasmic membrane tends to be regular without much denting, bumps, pseudopods, or shredding.The cell in the first image on the right shows the relative size, nucleus, and gritty basophilic cytoplasm of a classic myeloblast. Note that there is a small cluster of red primary granules present which, in addition to its other features, help to identify this cell as a myeloblast.The second image shows a myeloblast (blue arrow) at a later stage that is not quite a promyelocyte but is very close. The nucleoli are still prominent, the size has not changed much, and the cytoplasm is still only about 1/3 of the cell. There are a few more primary granules but they are not prominent enough to consider this cell a progranulocyte.While the myeloid sequence tends to be the predominant cell type found in normal bone marrows, myeloblasts should make up less than 5% of the bone marrow's nucleated cells.

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Promyelocytes are generally larger than myeloblasts, measuring approximately 12 to 20 microns. The nucleus is similar in size to the myeloblast but the cytoplasm is more abundant at this stage. The nucleoli will begin to close and become less prominent than in the blast stage. The chromatin strand texture in promyelocytes tends to become slightly more coarse and clumped than the chromatin pattern present in a myeloblast. Promyelocyte cytoplasm will have a gritty basophilic color and texture; however, there will also be prominent primary granules. These granules will look like red/purple grains of sand. With careful observation, one can note the cuboid nature of the granules. In the top image to the right notice the size of the promyelocyte on the right hand edge (red arrow),versus the other myeloid cells in the frame. Notice how basophilic the cytoplasm is compared to the more mature myelocytes that are present. Observe the prominent, red, primary granules, which stand out against the basophilic background.In the bottom image on the right, the promyelocyte (blue arrow) has matured a bit more, giving it an appearance closer to an early myelocyte. Though the overall size of the cell has not decreased noticeably (as what happens as cells mature), the depth of the basophilia is not as prominent, nor are the primary granules as obvious as they were in the cell shown in the top image. While the nucleoli are obvious in both cells, the chromatin texture in the cell indicated by the arrow in the bottom image is a bit more clumped and coarse. Also notice the clearing/ lighter color in the Golgi (perinuclear) zone of the bottom cell (indicated by the green arrow). This is where the first development of neutrophil secondary granules will become evident as the cell progresses to the next stage of maturation.

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The next stage of the myeloid maturation sequence is the myelocyte. The cytoplasm of this cell begins to produce specific, secondary granules. If the cell is destined to be a neutrophil these secondary granules will be pink/tan and will cause the basophilic color to lighten and breakup. At the "dawn" of neutrophilia, these secondary granules are most obvious in the golgi area. As the cell matures closer to a metamyelocyte, they fill the entire cytoplasm.While the cytoplasm shifts to producing secondary granules it also looses the prominence of its primary granules. In situations where the bone marrow is stressed or forced to make neutrophils quickly, as in sepsis or during certain therapeutic injections, some of these primary granules may persist as "toxic granules".At the same time the secondary granule production begins, the nucleus is shrinking and condensing. The nucleoli close and disappear, the chromatin gets coarser/denser and more clumped, and the chromatin gets tighter darker and more compact.The very early myelocyte (red arrow) in the top image to the right still displays its immature features. While the chromatin is not as condensed as in the intermediate and late stage myelocytes in the bottom image, notice how the cytoplasm no longer has the darker basophilic color of a promyelocyte. There are clusters of neutrophil secondary granules that are changing and breaking up the solid basophilic color. Notice too, that you can no longer see any red/purple primary granules. In this cell the cytoplasm is leading the maturational dance and the nucleus is lagging.The bottom image to the right shows two myelocytes (blue arrows): one intermediate in maturity, one a bit more mature, as well as a metamyelocyte (green arrow). Notice how the size of the cell continues to shrink as the cell matures. It is apparent that both the nucleus and the cytoplasm of the metamyelocyte adjacent has decreased in size and the chromatin has condensed/clumped as the cell matured toward a metamyelocyte.

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Segmented Neutrophil

The segmented neutrophil is the end stage of maturation in the myeloid lineage. The cell is similar in size to the band neutrophil and has a well granulated cytoplasm with a deeply condensed, knotted and clumped chromatin pattern. The chromatin pinches into several segments, usually separated by visible filaments. In some segmented neutrophils, this filament is inferred by the folding and shape of the nucleus.The top image on the right shows the classic morphology of a segmented neutrophil. The nucleus of a normal segmented neutrophil has two to five lobes, connected by thin filaments. Six or more lobes is an indication of abnormal development, usually related to B12 or folate deficiency.The bottom image shows the progression from band neutrophil (red arrows) to early segmented neutrophil (blue arrow) and finally to fully-mature segmented neutrophil (green arrow). Take a close look at the cell closest to the promyelocyte. You can see a drumstick-like projection arising from the end terminal segment. This can be seen in smears on female patients and is a Barr body or inactivated X-chromosome.

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Pronormoblast (Proerythroblast)

The pronormoblast, or erythroblast, is the earliest stage in erythroid maturation. It is a very round cell that is about the same size as a myeloblast. It has a distinctive deeply basophilic, velvety cytoplasm that does not have the fine background grittiness found in the myeloblast. A pronormoblast typically has a round, centrally-located nucleus , unlike a myeloblast that typically has an eccentric nucleus.The chromatin texture is coarser than myeloid chromatin and is more reticular and bumpy, almost like beads on a string. The pronormoblast will have multiple prominent nucleoli. The nuclear membrane appears highlighted compared to other cell types and there will be small breaks in the membrane that are known as nuclear pores. The erythroid lineage is the only cell line that has nuclear pores, which can help to distinguish intermediate erythroid precursors from lymphocytes.The upper image on the right shows a pronormoblast (red arrow) adjacent to a few monocytes (blue arrows). Notice that the pronormoblast is round and regular and the cytoplasm is intensely basophilic. Observe the central placement of the round nucleus and the nucleoli. Notice the coarse and grainy chromatin texture as well.The lower image on the right shows a late pronormoblast (red arrow) with a few later stage erythrocyte precursors (blue arrows). While the overall size of the late pronormoblast shown in this image is similar to the cell in the upper image, notice the less prominent nucleoli with the classic reticular grainy pattern of the chromatin. The cytoplasm still has the midnight-blue, velvety-look of a pronormoblast.

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Erythrocytic Cells: Introduction

When performing bone marrow cell identification, it is necessary to differentiate the stages of erythrocyte development. This differs from a peripheral blood differential, where the term "nucleated red blood cells" ("NRBCs") is used to describe all stages of circulating normoblasts. As with the myeloid sequence, there is a continuum in the erythroid maturation process in terms of nuclear and cytoplasmic morphology. Becoming familiar with the range of variation in each nucleated erythrocyte stage will make bone marrow differentials less intimidating.The image to the right shows several different stages of erythroid maturation with several clusters of NRBCs all maturing together.

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Monocytes progress through maturational stages in a similar fashion to the myeloid series before entering the peripheral blood circulation. The final stage of monocyte maturation into macrophages occurs after they have migrated out of the peripheral blood and into the surrounding tissues via diapedesis. Mature macrophages are also found in the bone marrow. The monocyte lineage does not maintain a maturational pool in the bone marrow as large as the myeloid pool. As a result, the monoblast stage is infrequently noted in most normal bone marrows.Monoblasts are the largest blasts of all the hematopoeitic cell lines present in the bone marrow. They have a large, round, centrally-placed nucleus with soft, fine-stranded chromatin. They normally have a single, large, prominent nucleolus. The cytoplasm is very generous and has a fine, grainy texture. In the monoblast stage, the cytoplasm will be basophilic, similar to other blasts, but will possess a slightly lighter shade of blue. In the monoblast, the color will shift to blue-gray as the cell matures into a monocyte.The top image on the right shows a single monoblast. Notice the large, round nucleus, the single large nucleolus and the generous blue, grainy cytoplasm. The second image shows a group of monocyte precursors. The large cell at the top is a monoblast (see red arrow). Notice the round and flat look of the nucleus in the blast compared to the other stages. Observe the nuclear shape becoming more folded and three-dimensional as the cell matures.

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Lymphocytes mature in the lymph nodes rather than in the bone marrow and therefore are not routinely assessed when deciding if a marrow has "trilinear" (myeloid, erythroid, megkaryocytic) maturation. However, they are normally present in the bone marrow and, when clustered in a lymphoid follicle, can be very prominent. Since lymphocytes mature in the lymph nodes, they will appear identical to peripheral blood lymphocytes when viewed in the bone marrow. They will have the same range of variation in size and cytoplasm and will demonstrate the same types of viral transformations noted in the peripheral blood. Viral/atypical lymphocytes are combined together with normal lymphocytes in a bone marrow differential count and not placed into their own category, as they are in a peripheral blood differential. However, the hematopathologist may include this information in the interpretation, if these changes are noted.Lymphocytes can be found scattered throughout the bone marrow and must be distinguished from early erythroid precursors, which they can closely resemble. Lymphocytes are frequently found in and around early NRBC clusters. In the top image on the right, notice the medium-sized lymphocyte (red arrow) next to the two basophilic normoblasts (blue arrow). The color and texture of the scant lymphoid cytoplasm is almost identical to the NRBC, which can be a bit confusing. However, observe the differences in the nuclei between the two cell types. The lymphocyte has a less distinct chromatin clumping pattern than the basophilic normoblasts and the lymphocyte does not have any "nuclear pores." Also, the lymphocyte has an irregularly-shaped nucleus that is hugging the cytoplasmic border, while the NRBC has a round and regular, centrally-placed nucleus. Identify the three lymphocytes circling the NRBCs in the second image (see red arrows). Notice the chromatin of the lymphocytes; the lymphoid smudgy/clumpy pattern is certainly not as dense and clumped as what is noted in the NRBCs. This nuclear difference becomes more pronounced as the erythroids mature. The cytoplasmic differences should be more apparent as well, since lymphocytes will never produce hemoglobin.

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General Laboratory Question Bank - Review Mode (no CE)
What is the normal ratio of erythroid to myeloid cells found in the normal bone marrow:View Page

Hematology / Hemostasis Question Bank - Review Mode (no CE)
The red cells in this illustration exhibit which of the following abnormal erythrocyte shapes:View Page
Pluripotential stem cells are capable of producing which of the following:View Page
Which of the following is the proper designation for the pluripotential stem cell that is a precursor for both myeloid and lymphoid cell lines:View Page

Introduction to Bone Marrow
The M:E ratio represents the ratio of: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.

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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.

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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.

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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.

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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.

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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%

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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Red Cell Disorders: Peripheral Blood Clues to Nonneoplastic Conditions
Poikilocytosis Review Table

Cell TypeImageCellular DescriptionAssociated Diseases and ConditionsTeardrop cellRed blood cells (RBCs) are shaped like a teardrop with a projection extending from one end.Myelofibrosis with myeloid metaplasia (MMM)SpherocyteRBCs smaller than normalNo central pallorRound rather than disc-shapedHereditary spherocytosisCertain hemolytic anemiasSevere burnsTarget cellRBCs with characteristic bull's-eye morphology due to hemoglobin distribution.Hemoglobinopathies (e.g., sickle cell disease)Certain thalassemiasIron deficiency anemiaSplenectomySevere liver diseaseSickle cellRBCs contain hemoglobin S.Thorn or crescent-shapedSickle cell anemiaStomatocyteRBCs with thin, elongated area of central pallor (slit-like, or coffee-bean-shaped on peripheral blood smears).Three-dimensionally, RBCs are cup-shaped.Hereditary stomatocytosisAlcohol-related diseaseLiver diseaseRh null phenotypeArtifactSchistocyte (fragmented red cells)RBC blood cell fragments or piecesVary widely in size and shapeSevere burnsHemolytic uremic syndrome (HUS)Microangiopathic hemolytic anemia (MAHA)Disseminated intravascular coagulation (DIC)Thrombotic thrombocytopenic purpura (TTP)Ovalocyte (elliptocyte)RBCs are elongated-oval, cigar, or pencil-shapedHereditary elliptocytosisMegaloblastic anemiaMyelophthisic anemiaCertain thalassemiasSevere iron deficiency Acanthocyte (Spur cell)RBCs demonstrating irregularly-spaced, spiny projections that vary in size and numberNo central pallor.AbetalipoproteinemiaSevere hepatic diseaseMyeloproliferative disordersMAHANeuroacanthocytosissyndromesEchinocyte (Burr cell)RBCs have short and evenly-spaced, rounded projections surrounding the cellCentral pallor presentUremiaHeart diseasePyruvate kinase deficiencyStomach cancersBleeding peptic ulcersBite cellRed cells that appear to have bites taken out of them (Image A)Supravital stain reveals the presence of Heinz bodies--precipitated denatured masses of hemoglobin (Image B) Disorders associated with Heinz body formation:Unstable hemoglobinsChemical poisoningG-6PDHemolytic anemia associated with severe alcoholic liver disease

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Red Cell Morphology
Teardrop Cells, continued

Conditions in which teardrop cells can be found include myelofibrosis/myeloid metaplasia, bone marrow metastases, thalassemias, and anemias causing Heinz body formation. Dacryocytes are not diagnostically indicative of any specific condition.

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Variations in White Cell Morphology -- Granulocytes
Auer Rods

Auer rods are red staining, needle-like bodies seen in the cytoplasm of myeloblasts, and/or progranulocytes in certain leukemias. Auer rods (see arrow in image) 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 non-lymphocytic (myeloid) 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 are always classified as pathological.

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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 actually azurophilic granules, normally present in early myeloid forms, but 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 phenomenon may be seen in cells which also contain Döhle bodies and/or vacuoles. Cells containing toxic granules may have decreased numbers of specific granules. Note: 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. The blue arrow in the image points to a neutrophil with toxic granulation. Döhle bodies are also present in the cell, indicated by the red arrows.

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White Cell and Platelet Disorders: Peripheral Blood Clues to Nonneoplastic Conditions
The cells included in the composite image were found in the peripheral blood smear of a patient with the following results:total WBC of 24.5 x 109/L. Differential count:myelocytes 1 metamyelocytes 4 band neutrophils 15 segmented neutrophils 40 monocytes 8 eosinophils 2 basophils 1 lymphocytes 29This 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.

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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.

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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

The following pages in this presentation includes a series of white blood cell and platelet abnormalities (nonneoplastic) that may be identified in a peripheral blood smear. Many cases will simulate the practice of a peripheral smear review by a hematology technologist. He or she must assess what responses in patient care may be triggered by the clinician attempting to interpret the reported findings on a peripheral smear.Observations of white blood cell abnormalities in the peripheral blood smear should be reported in order to direct the physician to an immediate specific diagnosis, such as: Atypical lymphocytes, suggesting infectious mononucleosis rather than leukemia Toxic granules in neutrophils, as found in acute infections, or atypical granules suggesting a genetic disorder An unusual mix of cells, such as too many or too few neutrophils, monocytes, or other myeloid cells The presence of giant platelets, myelocytes, or other cells, suggesting a myelodysplastic syndromeIn summary, laboratory data should be presented to clinicians in a user-friendly fashion to promote effective decision making.

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A peripheral blood smear with many myeloid cells was presented for morphology review (see image on the right). Toxic granulation and vacuoles in the neutrophil most likely represent which of the following conditions?View Page

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