Page 143 - Concise Pathology for Exam Preparation ( PDFDrive )

128 SECTION I General Pathology

Malignant
squamous
cells

keratin pearls

Atypical mitosis

FIGURE 6.3. Well-differentiated squamous cell carcinoma of oral mucosa comprising
anaplastic squamous cells, at places, forming keratin pearls (H&E; 2003).

Q. Differentiate between benign and malignant tumours.

Ans. Differences between benign and malignant tumours are shown in Table 6.4.

TABLE 6.4. Contrasting features of benign and malignant tumours

Features Benign Malignant
Gross features
Boundaries Encapsulated/well circumscribed Ill circumscribed/unencapsulated
Size Usually small Usually large
Secondary changes Less frequent More frequent
Surrounding tissue Compressed Invaded
Microscopic features
Pattern Resembles tissue of origin Poor resemblance to tissue of origin
Polarity Retained Lost
Anaplasia Absent Present
Mitoses Present, few, typical Present, many, atypical as well as
typical
Tumour giant cells Rare, without atypia Common, with atypia
Cytogenetic changes Rare Common
Physiology of cells/function Maintained Lost
Growth rate Low High
Local invasion Rare Common
Metastasis Absent Present

Q. Define local invasion.
Ans. Most cancers are accompanied by progressive infiltration and destruction of the sur-
rounding tissue, referred to as local invasion.

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