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NEOPLASIA
• Neoplasia – new growth
• New growth produced – TUMOUR / NEOPLASM
• However all new growths – NOT a neoplasm
• Also can occur in• Embryogenesis• Regeneration and Repair• Hyperplasia• Hormonal Stimulation
Definition
• Mass of tissue formed as a result of Uncontrolled, Excessive, Abnormal, Autonomous and Purposeless proliferation of cells
• Science of study of Neoplasms – Oncology• Oncos = tumour, Logos = study
Types
• Benign • Malignant
• Common term for malignant tumours – CANCER
• Term CANCER means CRAB – “since it sticks to the part like a crab”
• Benign• Slow Growing• Localised• No much difficulty to the Host
• Malignant• Rapidly growing• Spread throughout the body• Much difficulty to the host
Components
• 2 Basic components of tumours• Parenchymal cells• Stromal cells
• Parenchyma (Parenchymal cells)• proliferating tumour cells • Determines the nature and evolution of the
tumour
• Supportive Stroma(Stromal cells)• Fibrous connective tissue and blood vessels• Framework on which parenchyma present
Nomenclature
• Based on the parenchymal component comprising them
• Usually, Benign – ‘oma’ is the suffix
• Malignant tumours• Epithelial – Carcinoma• Mesenchymal - Sarcoma
Exceptions
• Some cancers – Highly undifferentiated cells • Hence called ‘Undifferentiated malignant
tumours’
• Exceptions for ‘oma’ rule:-• Carcinoma of Melanocytes – MELANOMA
Carcinoma of Hepatocytes – HEPATOMA• Malignancy of Lymphoid – LYMPHOMA• Malignancy of Testis - SEMINOMA
Special Categories
• Mixed tumours • 2 types of tumours present in the same
tumour
Eg:- Adenosquamous carcinoma – EndometriumAdenoacanthoma – EndometriumCarcinosarcoma- Thyroid
• Collision Tumour – Morphologically two different tumour in the same organ not mixing with each other
• Mixed tumour of salivary gland (Pleomorphic adenoma)
• Benign tumour with epithelial and mesenchymal elements
Teratomas
• Totipotent cells – All three germ layers• Endo/meso/ ecto derms
• 2 types• Benign – Mature• Malignant – Immature
Most common sites – Testis/ Ovary (gonadal teratomas)
Blastomas
• Embryomas• Arise from embryonal components normally
forming the organs & tissues of embryogenesis
• Frequent in < 5 yrs age group• Eg:- Neuroblastoma• Nephroblastoma(Wilms’ tumour)• Hepatoblastoma, Medulloblastoma
Hamartoma
• Benign• Mature but disorganised tissues indigenous to
the particular organ
• Eg:- hamartoma of lung – Mature cartilage, smooth muscle and epithelium
Choristoma
• Ectopic islands of normal tissue• Generally a heterotopia – not a true tumour
Characteristics of Tumours
• Rate of growth• Clinical & Gross features• Microscopic features• Local Invasion• Metastasis
Rate of Growth
• 2 main factors• Rate of division and destruction of cells• Degree of Differentiation
Rate of Division/Destruction
• Malignant cells – Increased mitotic rate• Decreased death rate
• Don’t follow normal cell cycle control – immortal
• If division is high, centre of tumour – less nourishment leading to ischaemic necrosis
Degree of differentiation
• Rate of growth directly proportional to Degree of Differentiation
• Poorly differentiated – Aggressive growth• Well differentiated – Slow growth
Regulation of tumour growth
• Due to Growth factors like• EGF – Epidermal growth factor• FGF- Fibroblast growth factor• PDGF- Platelet derived growth factor• CSF – Colony stimulating factor• TGF – Transforming growth factor
• Also Interleukins play a major role
Clinical and gross features
• Clinically • Benign – slow growing
• Depending on location• Asymptomatic – subcutaneous lipoma• Symptoms – Meningioma of CNS
• Malignant tumours• Rapidly growing• Invade superficially or into deeper structures• Spread to distant tissues• Systemic features – anorexia, weight loss,
tiredness
Grossly
• Features like
• Colour• Texture• Consistency helpful in distinguishing
• Malignant tumours grossly may appear fungating, ulcerative, papillary, hemorrhagic, infiltrating
• Benign • Well circumscribed/ encapsulated• Freely movable and firm
• Malignant• Poorly circumscribed• Fixed and irregular in shape• Secondary changes like hemorrhage & infarction
Microscopic features
• Greatest importance for classifying
• Features to be appreciated • Microscopic pattern• Cytomorphology• Tumour angiogenesis and stroma• Inflammatory reaction
Microscopic Pattern
• Variety of patterns
• Epithelial – sheets, cords, acini, columns– Solid or papillary
• Mesenchymal – Interlacing bundles, whorls, fascicles– Usually separated by intercellular matrix
• Mixed – Teratoma/ Pleomorphic adenoma
Cytomorphology of Neoplastic Cells
• Differentiation– Extent of resemblance to the normal tissue– Well/ Poorly differentiated
• Anaplasia– Lack of differentiation– Characteristic feature of Malignancy
Indicators of Anaplasia
• Basal Polarity– Normally nucleus oriented towards basement
membrane• Pleomorphism– Variation in size and shape of cells
• N/C ratio– Nuclear cytoplasmic ratio
• Anisonucleosis– Variation in shape and size of nucleus
• Hyperchromatism– Amount of nucleoprotein
• Nucleolar changes– Depends on NOR – Nucleolar Organising Region
• Mitotic Figures– Normal or Abnormal
• Tumour giant cells• Chromosomal abnormalities
Tumour angiogenesis and Stroma
• Tumour Angiogenesis• Formation of new vessels from pre-existing
ones• Provide nourishment to the tumour
• 2 factors• Microvascular density• Central necrosis
• Microvascular Density• New capillaries added to the tumour• Accesses the rate of growth of tumour
• Central necrosis• Fast growing tumours – poor blood supply to
the interior – undergo necrosis
Tumour Stroma
• Collagenous tissue• Scanty or Excessive
• Scanty – soft & fleshy – Sarcomas/lymphoma• Excessive – Hard & Gritty (Infiltrating DC)
• If epithelial tumour composed • Only of Epithelial cells – Medullary carcinoma• Excessive stroma – Desmoplasia/ Schirrous
Inflammatory Reaction
• Acute or Chronic• Chronic – chiefly of lymphocytes, plasma cells,
macrophages
• Granulomatous reaction in the absence of ulceration – good immunologic response
• Eg: Seminoma testis, Malignant melanoma, Medullary carcinoma of breast
2 Most Important features
• Local Invasion– Direct Spread
• Metastasis– Meta=transformation, stasis=residence– ‘spread of tumour by invasion in such a way that
discontinuous secondary tumour mass formed at the site of lodgement’
– Distant Spread
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