Dr. Saleem Shaikh
 “Neoplasia” means new – growth,
 All new growths can not be grouped under neoplasia, new growth can
be seen in embryogenesis, regeneration and repair.
 Definition: A neoplasm is an abnormal mass of tissue, the growth of
which exceeds and is uncoordinated with that of the normal tissue,
and persists in the same excessive manner after cessation of the
stimulus which evoked the change.
 The branch of science dealing with the study of neoplasm or tumors is
known as ‘Oncology’
 Neoplasia is the process, the resulting growth is known as Neoplasm
 All tumors have two basic components –
Parenchyma – comprising of proliferating tumour cells. Parenchyma
determines the nature and evolution of the tumour
Stroma – composed of fibrous connective tissue and blood vessels, it
provides the framework for the tumour cells to grow.
Neoplasms may be benign or Malignant
Benign – the tumour are slow growing and localised
Malignant - when they proliferate rapidly and spread throughout the
body.
The common term used for all malignant tumours is cancer.
The word cancer means crab; “it holds on to the body like a crab”
Nomenclature:
 The tumours are named based on their parenchymal component.
 The suffix ‘- oma’ is added to benign tumours
 The malignant tumours of epithelial origin are called as ‘carcinoma’
 Malignant tumours of connective tissue origin are named as ‘sarcomas’
 Although this nomenclature is applicable to most tumours there are
some exceptions
Melanoma – carcinoma of melanocytes
Hepatoma – carcinoma of hepatocytes
Lymphoma – malignant tumour of lymphocytes
Leukaemia – malignant tumour of white blood cells
 Special categories of tumours:
 Mixed tumours – when two types of tumours are combined in the same
tumour it is known as mixed tumour – ex: adenosquamous carcinoma
 Teratoma: these tumours are made up of various types of tissues, which
arise from undifferentiated cells of the three germ layers – most
common site is the ovaries and testis
 Blastomas: also known as embryomas are a group of malignant
tumours which arise from embryonal cells. These tumours occur most
commonly in children – retinoblastoma
 Hamartoma: is a benign tumour like growth made up of mature cells of
the same tissue and have limited growth potential
 Choristoma: it is similar to hamartoma in behaviour but the cells are
not from the same tissue (ectopic)
 Majority of the neoplasms are categorised clinically and
morphologically into benign and malignant on basis of
certain characteristics –
1. Rate of growth
2. Cancer phenotype and stem cells
3. Clinical and gross features
4. Microscopic features
5. Local invasion
6. Metastasis (distant spread)
 Rate of growth – the tumour cells grow rapidly than normal cells. In
general Benign tumours grow slowly and malignant tumours grow
rapidly.
Rate of production, rate of cell of loss
Degree of differentiation of the tumour.
Differentiation is defined as the extent of morphological and functional
resemblance of parenchymal tumour cells to corresponding normal
cells.
Poorly differentiated tumours grow more rapidly than the well
differetiated tumors.
 Cancer phenotype and stem cells:
Cancer cells escape death signals and achieve immortality
Cancer cells perform less or no function
Imbalance between cell proliferation and cell death in cancer causes
excessive growth
Cancer cells arise from stem cells present in the tissues
Clinical:
Benign tumors are usually asymtomatic and grow slowly, Freely movable,
more often firm and uniform.
Malignant tumors grow rapidly, may ulcerate the surface and invade into
deeper tissues. Haemorrhage and ulceration seen more often.
Gross features:
Benign tumours are generally spherical or ovoid in shape, encapsulated
or well circumscribed.
Malignant tumours are irregular in shape. Poorly circumscibed and
extend into adjacent tissues.
 Microscopic features: microscopic characteristics of a tumour are of
great importance in recognising and classifying tumours.
the features which are seen are :
1. microscopic pattern – epithelial or mesenchymal in origin
2. Cytomorphology of neoplastic cells – differentiation and Anaplasia
3. tumour angiogenesis and stroma – in order to provide nutrition to
the growing cells, new blood vessels are formed from old vessels.
the tissue stroma may be excessive or scanty (less),
If an epithelial tumour is made up of only parenchymal cells and very less
stroma then it is called as MEDULLARY.
If there is excessive connective tissue stroma seen in an epithelial tumour
then it is called as DESMOPLASTIC.
BENIGN
 Nuclear variation in size
and shape minimal
 Diploid
 Low mitotic count, normal
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mitosis
Retention of specialisation
Structural differentiation
retained
Organised
Functional differentiation
usually
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MALIGNANT
Nuclear variation in size and
shape minimal to marked,
often variable
Range of ploidy
Low to high mitotic count,
abnormal mitosis
Loss of specialisation
Structural differentiation
shows wide range of changes
Not organised
Functional differentiation
often lost