Page 302 - Textbook of Pathology, 6th Edition

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SECTION II

Figure 12.3 Schematic representation of differentiation of multipotent stem cells into blood cells.

Bone marrow examination may be performed by two conditions, fungi (e.g. histoplasmosis) and parasites (e.g.
Haematology and Lymphoreticular Tissues
methods—aspiration and trephine biopsy. A comparison of the malaria, leishmaniasis, trypanosomiasis). Estimation of the
two methods is summarised in Table 12.1. proportion of cellular components in the marrow, however,
BONE MARROW ASPIRATION. The method involves can be provided by doing a differential count of at least 500
suction of marrow via a strong, wide bore, short-bevelled cells (myelogram, Table 12.2). In some conditions, the
needle fitted with a stylet and an adjustable guard in order marrow cells can be used for more detailed special tests such
to prevent excessive penetration; for instance Salah bone as cytogenetics, microbiological culture, biochemical
marrow aspiration needle (Fig. 12.4,A). Smears are prepared analysis, and immunological and cytological markers.
immediately from the bone marrow aspirate and are fixed
in 95% methanol after air-drying. The usual Romanowsky TREPHINE BIOPSY. Trephine biopsy is performed by a
technique is employed for staining and a stain for iron is simple Jamshidi trephine needle by which a core of tissue from
performed routinely so as to assess the reticuloendothelial periosteum to bone marrow cavity is obtained (Fig. 12.4,B).
stores of iron. The tissue is then fixed, soft decalcified and processed for
The marrow film provides assessment of cellularity, histological sections and stained with haematoxylin and
details of developing blood cells (i.e. normoblastic or eosin and for reticulin. Trephine biospy is useful over
megaloblastic, myeloid, lymphoid, macrophages and aspiration since it provides an excellent view of the overall
megakaryocytic), ratio between erythroid and myeloid cells, marrow architecture, cellularity, and presence or absence of
storage diseases, and for the presence of cells foreign to the infiltrates, but is less valuable than aspiration as far as
marrow such as secondary carcinoma, granulomatous individual cell morphology is concerned.