ABSTRACT
'An increase in size of an organ or tissue through an increase in the number of cells'. The cells mature to normal size and morphology. A tumour-like malformation composed of a haphazard arrangement of the different amounts of tissues normally found at that site. Grows under normal growth controls of the body. Examples: Pouts–Jigger’s polyps of bowel, haemangiomas. Disordered cellular development characterised by increased mitosis and pleomorphism BUT without the ability to invade through the basement membrane and metastasize to distant sites. Severe dysplasia = carcinoma in situ. As a general rule, carcinomas typically spread via the lymphatic route; sarcomas typically spread by the haematogenous route. However, there are exceptions to this rule, e.g. follicular thyroid carcinomas spread via the bloodstream to bone. The survival and growth of cells that have migrated or have otherwise been transferred from a malignant tumour to a site or sites distant from the primary.
