Wintrobe's Clinical Hematology 14e SC

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Part 1: Laboratory Hematology— SECTION 1

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FIGURE 1.6 Bone marrow core biopsy. Histologic preparation of the bone marrow core biopsy following fixation and decalcification. The biopsy is stained with hematoxylin and eosin. This preparation allows for optimal evaluation of bone marrow cellularity and interaction of bone marrow cells with bony trabeculae and

is helpful in evaluating extrinsic features, such as metastatic tumor or fibrosis in the marrow. Panel A (low power) showing bony spicules and marrow in section of

bone marrow core biopsy. Panel B (high power) showing morphologic detail of hematopoietic tissue within the section.

oil immersion magnification in most marrows. Only intact cells are

to give an approximation of the size of the bone core within the needle.

evaluated; all bare nuclei are excluded. Counting is performed in an

The biopsy needle is rotated and gently rocked to free the biopsy from the

surrounding bone and then advanced slightly farther. The biopsy is then

area where few bare nuclei are present and the cells are not overlapping,

removed from the bone by withdrawing the needle, and slight positive

found in clusters, or artifactually distorted because of the spreading

pressure may be applied using a syringe. The biopsy is expressed from

artifact. This is usually in the dispersed cell zone adjacent to the spicule.

the needle by the stylet. Touch preparations of the bone biopsy should

It should be noted that spicules may be absent in pediatric marrows

be made, particularly if no aspirate was obtained, to allow cytologic

where marrow cells will be uniformly dispersed. Reference ranges

examination of the bone marrow elements. The bony core is then fixed, decalcified, and processed for histologic examination. 113,114 Ancillary

for the percentage of bone marrow cell types vary widely between

laboratories and are used only as guides for what is to be expected in normal bone marrow samples 111 (for example of reference ranges,

testing can often be performed on additional bone marrow cores when

see Table 1.3 ). The proportions of each cell type and progression of

no material can be aspirated, so collection of more than one core biopsy

may be necessary.

the maturational sequence for myeloid and erythroid elements are

Once the biopsy is completed, manual pressure is applied to the site

determined from the differential counts. In addition, the myeloid to

for several minutes to achieve hemostasis. The site is then bandaged,

erythroid ratio may be calculated.

and the patient is instructed to remain recumbent so as to apply further

Differences in cell differential results among infants, children, and adults exist ( Table 1.4 ). 108,111,113,115 In general, lymphocytes are more

pressure for approximately 30 to 60 minutes. If a patient is thrombo-

cytopenic, pressure bandages should be applied and the site checked

commonly seen in the marrow of children, especially those younger

frequently for prolonged bleeding.

than 4 years, where they may compose up to 40% of the marrow cellularity. 116 Plasma cells are rare in the marrow of infants and chil- dren. Lymphocytes are much less numerous in adult bone marrows, < 20% of adult marrow cellularity. Lymphocyte and plasma cell counts in adults tend to be quite variable, perhaps usually making up

Staining and Evaluation of Bone Marrow Aspirates and Touch Preparations

The bone marrow aspirate or touch preparation slides are stained with

reflecting the tendency of these cells to be unevenly distributed in the

either Wright or May-Grünwald-Giemsa stains, similar to blood smears.

bone marrow of adults. Often, lymphoid cells are found in nodular

These stains allow excellent morphologic detail and allow differential

aggregates in older adults, and plasma cells tend to be associated with blood vessels. 117 During the first month of life, bone marrow erythroid cells are prom- inent because of high levels of erythropoietin 118 ; thereafter, the erythroid

counts to be performed. Unstained smears should be retained for possible special stains if indicated. 108,111

Evaluation of bone marrow aspirates gives little information about

the total cellularity of the bone marrow because of fluctuations in cell

cells make up 10% to 40% of the marrow cells. Relatively few early

erythroid precursors (normoblasts) are usually seen, and more mature

counts induced by peripheral blood contamination of the bone mar-

row specimen and preparation artifacts. An overall impression of the

forms predominate. Erythroid cells should be examined for abnormalities

cellularity may be given (ie, cellular or paucicellular). More accurate

in morphology as well as iron content because these features are often

evaluation of bone marrow cellularity requires examination of the bone

deranged in pathologic states. Myeloid cells are usually the predominant

marrow biopsy or particle clot section, although the biopsy represents

bone marrow element, and more mature cells predominate over immature

a tiny fraction of the total marrow and may also be subject to sampling error. 108,113 The stained aspirate smear will have a central zone of dark

myeloblasts. Children tend to have higher numbers of eosinophils and

eosinophilic precursor cells than do adults, although many medications,

Copyright © 2019 Wolters Kluwer, Inc. Unauthorized reproduction of the content is prohibited. marrow particles and stroma surrounded by a thinner area of dispersed bone marrow cells and red cells (Figure 1.5). Low-power examination allows evaluation of the adequacy of cellularity and of the presence of allergies, or infections may increase the bone marrow eosinophil count. Megakaryocytes constitute the least abundant cell type seen in the bone marrow, usually making up

< 1% of the cells. 108 In addition to the hematopoietic cells, a variety of other cells may

megakaryocytes. Infiltrating tumor cells or granulomas may also be seen by scanning the aspirate smear at low power. 111

be seen in bone marrow aspirates in varying proportions, including

The aspirate smear allows cytologic examination of the bone marrow

macrophages, mast cells, stromal cells, and fat cells. In children, os-

teoblasts and osteoclasts may be seen, although these cells are rare in

cells. A minimum of 500 nucleated cells should be evaluated under

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