Some of these slides are stained with Wrights stain and the rest can be used

Some of these slides are stained with wrights stain

This preview shows page 18 - 31 out of 37 pages.

Some of these slides are stained with Wright’s stain, and the rest can be used for special stains in case a good aspirate is not available. Imprints are valuable when the specimen has clotted or there is a dry tap.
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Bone Marrow Smear Dyes Marrow aspirate smears are stained with Wright or Wright Giemsa dyes using the same protocols as for peripheral blood film staining. Some laboratory managers increase staining time to compensate for the relative thickness of marrow smears compared with peripheral blood films. Marrow aspirate smears and core biopsy specimens may also be stained using a ferric ferricyanide ( Prussian blue ) solution to detect and estimate marrow storage iron or iron metabolism abnormalities. Further, a number of cytochemical dyes are used for cell identification or differentiation.
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Examination and Assessment of Stained Bone marrow Preparations The first thing to do is to look with the naked eye at a selection of slides and to choose from them the best spread films containing easily visible marrow particles. The bone marrow aspirate smears are scanned with a low power objective (10x) to select a suitable area for examining and performing the differential count. To find bony spicules Observe fat-to-marrow ratio, estimate cellularity Search for tumor cells in clusters Examine and estimate megakaryocytes
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Cellularity of Bone marrow The overall bone marrow cellularity is estimated by comparing the amount of hematopoietic tissue with the amount of adipose (fat) tissue. Fat appears as a clear space. It is expressed as the ratio of the volume of hemopoietic cells to the total volume of marrow . The reference range decreases with age. Infants have the highest cellularity (90%) and older adults the lowest (50%). An easy way to determine the normal expected cellularity range in an adult is (100% - Patient’s age)+/- 10%.
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For example, a normal 70-year-old adult has an overall cellularity between 20% and 40%. Cellularity varies with the site from which the bone marrow is taken E.g., Age 50 years: vertebrae = 75% sternum = 60% iliac crest = 50%
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By comparing with the age-related normal cellularity values, the microscopist classifies the observed area as hypocellular, normocellular, or hypercellular. If a core biopsy specimen was collected it provides a more accurate estimate of cellularity than an aspirate smear. If the percentage is increased for the age of the patient The marrow is said to be hypercellular or hyperplasic Such hyper cellular marrow is seen in: Myeloproliferative disorders (e.g. AML) Lymphoproliferative disorders (e.g., ALL, CLL) Infections Polycythemia
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If the percentage is decreased for the age of the patient The marrow is said to be hypo cellular or hypo plastic It is a finding in conditions associated with marrow failure Aplastic anemia Toxicity (drugs, chemicals)
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4.6.1 Cellularity of Bone marrow cont’d NORMAL/NORMOCELLULAR MARROW BIOPSY 26
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4.6.1 Cellularity of Bone marrow cont’d Hypocellular marrow 27 Aplastic marrow
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4.6.1 Cellularity of Bone marrow cont’d 28 Hypercellular marrow
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High Power: 100x objective Observe myelocytic and erythrocytic maturation Distinguish abnormal distribution of cells or cell maturation stages Perform differential count on 300 to 1000 cells Compute myeloid-to-erythroid ratio
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Bone Marrow Differential Count A bone marrow nucleated differential cell count should be performed to assess hematopoitic activity to compare the proportions of the different cell lineages with
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