Page 208 - Textbook of Pathology, 6th Edition

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Chapter 8
Chapter 8 Neoplasia

NOMENCLATURE AND CLASSIFICATION ‘Parenchyma’ comprised by proliferating tumour cells;
SECTION I
parenchyma determines the nature and evolution of the
INTRODUCTION. The term ‘neoplasia’ means new growth; tumour.
the new growth produced is called ‘neoplasm’ or ‘tumour’. ‘Supportive stroma’ composed of fibrous connective tissue
However, all ‘new growths’ are not neoplasms since and blood vessels; it provides the framework on which the
examples of new growth of tissues and cells also exist in the parenchymal tumour cells grow.
processes of embryogenesis, regeneration and repair, The tumours derive their nomenclature on the basis of
hyperplasia and hormonal stimulation. The proliferation and the parenchymal component comprising them. The suffix
maturation of cells in normal adults is controlled as a result ‘-oma’ is added to denote benign tumours. Malignant tumours
of which some cells proliferate throughout life (labile cells), of epithelial origin are called carcinomas, while malignant
some have limited proliferation (stable cells), while others mesenchymal tumours are named sarcomas (sarcos = fleshy)
do not replicate (permanent cells). On the other hand, (Fig. 8.1). However, some cancers are composed of highly
neoplastic cells lose control and regulation of replication and undifferentiated cells and are referred to as undifferentiated
form an abnormal mass of tissue. malignant tumours.
Therefore, satisfactory definition of a neoplasm or tumour Although, this broad generalisation regarding
is ‘a mass of tissue formed as a result of abnormal, excessive, nomenclature of tumours usually holds true in majority of
uncoordinated, autonomous and purposeless proliferation of cells instances, some examples contrary to this concept are:
even after cessation of stimulus for growth which caused it’. The melanoma for carcinoma of the melanocytes, hepatoma for
branch of science dealing with the study of neoplasms or carcinoma of the hepatocytes, lymphoma for malignant
tumours is called oncology (oncos=tumour, logos=study). tumour of the lymphoid tissue, and seminoma for malignant
Neoplasms may be ‘benign’ when they are slow-growing and tumour of the testis. Leukaemia is the term used for cancer of
localised without causing much difficulty to the host, or blood forming cells.
General Pathology and Basic Techniques
‘malignant’ when they proliferate rapidly, spread throughout SPECIAL CATEGORIES OF TUMOURS. Following
the body and may eventually cause death of the host. The categories of tumours are examples which defy the
common term used for all malignant tumours is cancer. generalisation in nomenclature given above:
Hippocrates (460-377 BC) coined the term karkinos for cancer 1. Mixed tumours. When two types of tumours are
of the breast. The word ‘cancer’ means crab, thus reflecting combined in the same tumour, it is called a mixed tumour.
the true character of cancer since ‘it sticks to the part For example:
stubbornly like a crab’. i) Adenosquamous carcinoma is the combination of
All tumours, benign as well as malignant, have 2 basic adenocarcinoma and squamous cell carcinoma in the
components: endometrium.

Figure 8.1 Examples of carcinoma (epithelial malignant tumour) (A) and sarcoma (mesenchymal malignant tumour) (B).