Page 213 - Textbook of Pathology, 6th Edition

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CHAPTER 8

Figure 8.3 Gross appearance of a prototype of benign and malignant tumour. Neoplasia

classifying such tumours (Fig. 8.2,B, F). However, anaplastic degree of differentiation, the extent of anaplasia is also
tumours differ greatly from the arrangement in normal tissue variable i.e. poorly differentiated malignant tumours have
of origin of the tumour and may occasionally pose problems high degree of anaplasia.
in classifying the tumour. As a result of anaplasia, noticeable morphological and
functional alterations in the neoplastic cells are observed.
2. Cytomorphology of Neoplastic Cells These are considered below and are diagrammatically
(Differentiation and Anaplasia) illustrated in Fig. 8.4:
The neoplastic cell is characterised by morphologic and i) Loss of polarity. Normally, the nuclei of epithelial cells are
functional alterations, the most significant of which are oriented along the basement membrane which is termed as
‘differentiation’ and ‘anaplasia’. basal polarity. This property is based on cell adhesion
molecules, particularly selectins. Early in malignancy,
Differentiation is defined as the extent of morphological
and functional resemblance of parenchymal tumour cells to tumour cells lose their basal polarity so that the nuclei tend
corresponding normal cells. If the deviation of neoplastic cell to lie away from the basement membrane (Fig. 8.5).
in structure and function is minimal as compared to normal ii) Pleomorphism. The term pleomorphism means variation
cell, the tumour is described as ‘well-differentiated’ such as in size and shape of the tumour cells. The extent of cellular
most benign and low-grade malignant tumours. ‘Poorly pleomorphism generally correlates with the degree of
differentiated’, ‘undifferentiated’ or ‘dedifferentiated’ are anaplasia. Tumour cells are often bigger than normal but in
synonymous terms for poor structural and functional some tumours they can be of normal size or smaller than
resemblance to corresponding normal cell. normal (Fig. 8.6).
Anaplasia is lack of differentiation and is a characteristic iii) N:C ratio. Generally, the nuclei of malignant tumour cells
feature of most malignant tumours. Depending upon the show more conspicuous changes. Nuclei are enlarged

Figure 8.4 Diagrammatic representation of cytomorphologic features of neoplastic cells. Characteristics of cancer (B) in a gland are contrasted
with the appearance of an acinus (A).