Chapter 5 Cancer and benign tumours/Fig 5.03.jpg

You can download this figure by right-clicking it and choosing 'Save Picture As...'

(A) Benign tumours are well circumscribed and the surrounding tissue often forms a capsule of fibrous tissue. (B) The cells of benign tumours closely resemble those of the normal tissue in which they arise. The nuclei are normal. As growth is slow, mitoses are uncommon, and as division is normal mitotic figures are of normal appearance. (C) Malignant tumours have infiltrative margins both on naked eye and on microscopic examination. (D) The nuclei are usually enlarged and the nucleoli active, indicating that the cell is active. The nuclei are often darkly staining – hyperchromatic – and variable in size and shape – pleomorphic – as the DNA content of the nucleus is frequently increased. Mitoses are often numerous and they are frequently abnormal in form indicating that the process of cell division may be abnormal. A tripolar mitosis is one in which the chromosomes are attempting to segregate towards three daughter cells.