and nomenclature in neoplasia

Chapter 20 Definitions and nomenclature in neoplasia

Neoplasia means new growth and is a broad term used to indicate a range of abnormal cellular proliferations. The term, therefore, includes established tumours (see below) and the cellular alterations that are recognized precursors to tumour development.

Tumour means ‘swelling’ and indicates the development of an abnormal population of cells. This change most commonly leads to the development of a mass (recognizable to the naked eye or only visible on histological examination, depending on its size) within preexisting non-neoplastic tissue, although this is not universally the case. For example, tumours of the bone marrow may replace normal marrow cells and lead to leukaemia without producing a recognizable mass.

Tumour development and differentiation

Most pathologists believe that tumours develop from a single primitive stem cell; these cells are themselves capable of development into one of several possible mature cell types. The histopathological appearances of tumour cells and tissues resemble normal tissues to a variable degree. The extent to which tumour tissues resemble normal tissues is termed the degree of differentiation of the tumour. Differentiation can only be assessed on microscopic examination of tumour tissue and is commonly subdivided into three categories (well, moderate and poor). Well-differentiated tumours show the greatest resemblance to normal tissues (e.g. an epithelial tumour forming glandular or ductal structures) while poorly differentiated tumours often comprise sheets of malignant cells showing little evidence of maturation into a particular tissue type. The growth pattern of a tumour is one component of the tumour characteristics that determine the tumour grade (see below).

Jul 3, 2016 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on and nomenclature in neoplasia
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