Download Neoplasia Intro

Neoplasia 1
a) Definition
b) 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. *
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Common terminologies
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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
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Differentiation & anaplasia
Rate of growth
Local invasion
Metastasis
Common terminologies in histopathology
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Dysplasia
Invasive carcinoma
Differentiation
Grade
Anaplasia
Pleomorphic,hyperchromatic,atypical
mitosis,tumour giant cells
Dysplasia
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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 (carcinomain-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 …..
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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.
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Morphological features of anaplasia
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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….
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Atypical Mitoses –
Increased number
Abnormal morphology
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tumour giant cells, necrosis
Words not to be confused
with neoplasm
Hamartoma
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Mass of disorganized but mature specialized
cells native to the organ in which the
structures arose.
E.g. pulmonary hamartoma
Choristoma
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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
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Shrinkage in the cell size by loss of cell
substance.
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Can be physiologic or pathologic
Hypertrophy
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↑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
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eg skeletal muscle hypertrophy
Uterus & lactating breast show both
hyperplasia and hypertrophy due to hormonal
stimulation.
Pathological hypertrophy
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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
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Complete absence of an organ or lack of
specific cells within the organ
Eg Sertoli cell only syndrome
Metaplasia
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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.
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