growth and spread

Chapter 23 Tumour growth and spread

Tumours form through neoplastic transformation of a primitive stem cell within the site of tumour origin. Tumours develop because the growth of these transformed cells has escaped the control mechanisms present within normal cells.

Benign and malignant tumours

Benign tumours grow by forming an expansile mass that gradually compresses adjacent tissues (Fig. 3.23.1 and Table 3.23.1). Examination of benign tumours with the naked eye shows that they are well-circumscribed lesions while histological examination may also reveal a compressed rim of non-neoplastic tissue. Sometimes a rim of fibrous tissue is present at the edge of benign tumours, and this is referred to as a tumour capsule. The clinical effect of compression of adjacent tissues by the tumour depends on the site (Ch. 24). Benign tumours do not possess the ability to metastasize to distant sites but they can still cause substantial damage (Table 3.23.2).


Feature Benign Malignant
Cardinal featuresa
Effect of primary tumour on adjacent tissues Compression Invasion
Edge of tumour Well defined Poorly defined
Distant metastases Absent Present
Other primary features
Vascular invasion: within lymphatics or blood vessels Absent Present
Cellularity: tumour cells per unit area of tumour Low High
Nucleus-cytoplasm ratio of tumour cell Low High
Differentiation: how much tumour overall growth pattern resembles that of its non-neoplastic counterpart Good Variable; often poor
Nuclear pleomorphism: size and shape of nuclei Mild Variable; may be marked
Mitotic index: morphological evidence of active cell division Low Variable; may be high

bMarked nuclear pleomorphism is often associated with an irregular nuclear chromatin pattern and/or nuclear hyperchromasia (dark nuclei as seen on routine H&E staining).

a Most commonly used to determine biological behaviour of tumours.


Primary site Adjacent structure Clinical problem
Breast SkinChest wall UlcerationTumour fixation
Brainstem Cardiovascular centre Death
Colon Bladder Fistula formation
Pancreas Common bile duct Obstructive jaundice
Lung OesophagusPulmonary artery DysphagiaFatal haemoptysis
Prostate Prostatic urethra Urinary retention

Malignant tumours form a mass at their primary site, which may compress but which also characteristically invades into adjacent tissues. The term cancer means crab and was coined in reference to the ability of malignant tumours to infiltrate adjacent tissues with a growth pattern that resembles a crab with long legs and pincers. Malignant tumours often create significant clinical problems at their primary site (Ch. 24) but may additionally spread (metastasize) to distant sites. This latter characteristic accounts for most of the mortality associated with malignant tumours and is the subject of much research. Metastasis may occur through one or more of several routes (Table 3.23.3). In order to metastasize, tumour cells must be able to perform certain tasks at different times (Chs 26–29):

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Jul 3, 2016 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on growth and spread

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