definition classification of tumors differences between benign and malignant tumors diagnosis of cancer

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Dr. Nikhitha Valluri (PharmD),
Assistant Professor,
Sree Dattha Institute of Pharmacy.
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DEFINITION :
A neoplasm or tumor is ‘a mass of tissue formed as a result of abnormal,
excessive, uncoordinated, autonomous and purposeless proliferation of cells even after cessation
of stimulus for growth which caused it’.
Neoplasms may be :
‘Benign’ - slow-growing and localised without causing much difficulty to the host, or
‘Malignant’ - proliferate rapidly, spread throughout the body and may eventually cause death of
the host.
The common term used for all malignant tumours is cancer.
Cancer = Karkinoma, Crab
Neoplasm = New Growth
Oncos = Tumor

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 All malignant cells arise from a transformation of a normal cell into an immortal cell
which growth uncontrolled.
 Such transformation occurs when the genetic blueprint - the cell’s DNA - is damaged or
altered.
 Every cell contain a series of genetic markers known as protooncogenes.
 All tumours, benign as well as malignant, have 2 basic components:
• ‘Parenchyma’ comprised by proliferating tumour cells.
• ‘Supportive stroma’ composed of fibrous connective tissue and blood vessels.
It provides the framework on which the parenchymal tumour cells grow.

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NOMENCLATURE :
The suffix ‘-oma’ is added to denote benign tumours.
Malignant tumours of epithelial origin are called carcinomas, while
malignant mesenchymal tumours are named sarcomas (sarcos = fleshy)

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PATHOLOGIC DIAGNOSIS
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Main methods of cancer diagnosis
1. Radiological diagnosis
2. 2. Cytological diagnosis.
3. Histological diagnosis.
4. Frozen section.
5. Heamatological diagnosis.
6. Immunohistochemistry.
7. Molecular diagnosis
8. Tumour markers

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Histological Methods
 These methods are most valuable in arriving at the accurate diagnosis.
 The tissue must be fixed in 10% formalin for light microscopic examination and in
glutaraldehyde for electron microscopic studies.
 Quick frozen section and hormonal analysis are carried out on fresh unfixed tissues.
 Morphological features of benign tumours resemble those of normal tissue and,
 while malignant tumours are identified by lack of differentiation in cancer cells termed
‘anaplasia’ or ‘cellular atypia’ and may invade as well as metastasise.

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For histological diagnosis the following methods of sampling is done:
 Biopsy- biopsy is a surgical removal of small piece of tissue for microscopic
examination for the presence of cancer cell.
There are three ways tissues can be removed for Biopsy:-
• Endoscopy
• Needle biopsy
• Surgical biopsy

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Cytological Methods
Cytological methods for diagnosis consist of :
 study of cells shed off into body cavities (exfoliative cytology) and
 study of cells by putting a fine needle introduced under vacuum into the lesion (fine needle
aspiration cytology, FNAC).
 i) Exfoliative cytology:
Cytologic smear (Papanicolaou or Pap smear) method was initially employed for detecting
dysplasia, carcinoma in situ and invasive carcinoma of the uterine cervix.
Also examination of sputum and bronchial washings; pleural, peritoneal,urine,
pericardial effusions; gastric secretions, and CSF.
The method is based on microscopic identification of the characteristics of malignant cells
which are incohesive and loose and are thus shed off or ‘exfoliated’ into the lumen.

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ii) Fine needle aspiration cytology (FNAC) :
The method consists of study of cells obtained by a fine needle introduced under vacuum into
the lesion, so called fine needle aspiration cytology (FNAC).
The superficial masses can be aspirated under direct vision while deep-seated masses such as
intra-abdominal, pelvic organs and retroperitoneum are frequently investigated by ultrasound
(CT)-guided fine needle aspirations.
The smears are fixed in 95% ethanol by wet fixation, or may be air-dried unfixed.
FNAC has a diagnostic reliability between 80-97% but it must not be substituted for clinical
judgement or compete with an indicated histopathologic biopsy.

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Histochemistry and Cytochemistry
It help the pathologist in identifying the chemical
composition of cells, their constituents and their
products by special staining methods.

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Immunohistochemistry
 This is an immunological method of recognising a cell by one or more of its specific
components in the cell membrane, cytoplasm or nucleus. These cell components combine
with specific antibodies on the formalin-fixed paraffin sections or cytological smears.
The complex of antigen-antibody on slide is made visible for light microscopic identification by
either fluorescent dyes (‘fluorochromes’) or by enzyme system (‘chromogens’).

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Tumour Markers (Biochemical Assays)
Tumour markers include: cell surface antigens (or oncofoetal antigens), cytoplasmic proteins,
enzymes, hormones and cancer antigens.
it can be used for prognostic and therapeutic purposes.

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