Neoplasia 1

a) Definitionb) Terminologies

Neoplasia “new growth”

Definition: “an abnormal growth of tissue, the growth of which exceed and is uncoordinated with that of normal tissues and persists in the same excessive manner after cessation of the stimuli which evoke the changes”.

Characteristic of neoplastic cells Clonal:The entire population of cells in a

neoplasm arose from a single cell Autonomous-independent of growth and

regulatory influences Excessive Disorganized Fundamental to the origin is genetic

abnormality, allowing excessive & unregulated proliferation that is independent of physiologic growth regulatory stimuli. *

Common terminologies

Tumour: neoplasm Oncology : (gk. Oncos = tumour) Cancer : Common term for all malignant

neoplasms. (latin: cancer = crab) Based on behavoiur: Benign,malignant Components: parenchyma (neoplastic),

stroma (non-neoplastic)

Characteristics of benign & malignant tumours Differentiation & anaplasia Rate of growth Local invasion Metastasis

Common terminologies in histopathology Dysplasia Invasive carcinoma Differentiation Grade Anaplasia Pleomorphic,hyperchromatic,atypical

mitosis,tumour giant cells

Dysplasia

Disorderly growth and maturation of cells that are not benign but not obviously malignant either.

Loss in the uniformity of individual cells & in their architectural orientation

Premalignant condition Stage linking non-neoplastic (metaplasia,

hyperplasia) and malignancy (carcinoma-in-situ)

Carcinoma-in-situ

Differentiation

Degree of resemblance of malignant (parenchyma) cells to normal cells both in morphology and function

Expression of genes in a tissue specific manner

Benign tumours are well differentiated

Differentiation …..

Malignant tumours lack differentiation Degree of differentiation is grade of a tumour Well differentiated Moderately differentiated Poorly differentiated

Anaplasia

Anaplasia: (to form backwards)

Parenchymal cells that are not differentiated,with loss of structural & fucctional differentiation of normal cells

Seen in malignancy.

Morphological features of anaplasia

Loss of polarity Pleomorphism: variation in size &shape Abnormal nuclear morphology Nuclear pleomorphism (anisokaryosis) Hyperchromatic –usually increased in

amount and irregularly distributed “clumped”

High N:C ratio (normal 1:4-1:6) Nucleoli : ↑ size

Morphological features of anaplasia….

Atypical Mitoses – Increased number Abnormal morphology

tumour giant cells, necrosis

Words not to be confused with neoplasm

Hamartoma

Mass of disorganized but mature specialized cells native to the organ in which the structures arose.

E.g. pulmonary hamartoma

Choristoma

Mass composed of normal mature cells or tissues in the wrong location (heterotopic rest)

Eg ectopic panceas in the stomach.

Other terminologies that you already know……

Atrophy

Shrinkage in the cell size by loss of cell substance.

Can be physiologic or pathologic

Hypertrophy

↑in the size of the cells, →increased size of the organ.

Due to synthesis of more structural components.

Occurs in non-dividing cells. Can be physiologic or pathologic.

Physiological Hypertrophy

eg skeletal muscle hypertrophy Uterus & lactating breast show both

hyperplasia and hypertrophy due to hormonal stimulation.

Pathological hypertrophy Cardiac hypertrophy in chronic

haemodynamic overload e.g. in systemic HT,coarctation of aorta,AS & MS with or without regurgitation.

Initially compensatory, later decompensates →CCF

Agenesis

Complete absence of an organ or lack of specific cells within the organ

Eg Sertoli cell only syndrome

Metaplasia

Metaplasia is a reversible change in which one adult cell type (epithelial or mesenchymal) is replaced by another adult cell type.

It is an adaptive substitution of cells that are sensitive to stress by cell types better able to withstand the adverse environment.

E.g. squamous metaplasia in bronchial epithelium.

Thank you