Disorder of growth, differentiation and tumours Flashcards
what is growth
process of INC IN SIZE
resulting from synthesis of specific tissue components
what is differentiation
process whereby a cell develops an OVERT SPECIALISED FUNCTION or MORPHOLOGY which distinguishes it from its parent cells
what is tumour differentiation
the extent of which neoplastic cells resemble comparable normal cells, both morphologically and functionally
what is anaplasia
lack of differentiation, it is a hallmark of malignant transformation
the “reversion from high level differentiation to lower level”
what are the morphological changes of anaplasia
- pleomorphism (variation in size and shape)
- abundance of DNA (nuclei disproportionally large)
- mitoses
- loss of polarity (orientation of cells is markedly disturbed)
what is neoplasia
new growth, the new growth itself is called neoplasm
describe neoplasia
what are the 2 types of tumour growth
an abnormal mass of tissue
- growth exceeds normal
- is uncoordinated with normal tissues
- persists even after STIMULI THAT EVOKED CHANGE IS REMOVED
- benign/malignant
tumour naming ends in suffix
oma
benign epithelial tumours are what
papilloma or adenoma
malignant epithelial tumours are called what
carcinomas
what is a malignant connective tissue tumour called
sarcoma
describe benign tumours
- non invasive and remain localised
- slow growth rate
- close histological resemblance to parent tissue
- fibrous capsule separates tumour from host tissue
- palpable (can be felt)
- eaily removed surgically
describe malignant tumours
- invasive and capable of spreading directly or by METASTASIS
- relatively rapid growth rate
- VARIABLE histological resemblance to parent tissue
borders of benign tumours are what compared to malignant tumours
benign: circumscribed or encapsulated
malignant: poorly defined or irregular
what is metaplasia
a REVERSIBLE change in which one adult cell type (epithelial or mesenchymal) is REPLACED by another adult cell type
metaplasia may be caused by what
what happens if these influences are persistent
an ADAPTIVE SUBSTITUTION of cells better ABLE TO WITHSTAND adverse environment (less sensitive)
- often in association with TISSUE DAMAGE, REPAIR and REGENERATION
- if the influences are PERSISTENT: it may initiate MALIGNANT TRANSFORMATION in metaplastic epithelium
what is dysplasia
disordered growth
describe dysplasia
where is it most commonly
- often METAPLASTIC EPITHELIA
- dysplastic lesions are often pre-neoplastic but does NOT NECESSARILY progress to cancer
- potentially disordered tissue architecture
what are the characteristics of dysplasia
- loss of uniformity of the individual cells and in their architectural orientation
- PLEOMORPHISM and often contain HYPERCHROMATIC NUCLEI that are abnormally large for the size of cell
- abundant MITOTIC figures iin ABNORMAL locations within epithelium (not confined to basal layers)
what are metastases
marks tumour as what
why is it clinically important
tumour IMPLANTS discontinuous with primary tumour
- marks tumour as malignant
- reduces possibility of a cure
what are the pathways of tumour metastatic spread
where do these occur
1) DIRECT SEEDING of body cavities or surfaces: PLEURAL, PERICARDIAL and PERITONEAL cavities
2) LYMPHATIC SPREAD: 2° tumour in LYMPH NODES
3) HAEMATOGENOUS spread by b.s: 2° tumour in ORGAN PERFUSED by blood from tumour
4) IMPLANTATION (after operation) rare
what is the molecular basis of carcinogenesis
- NON-LETHAL genetic damage
- single precursor cell incurs genetic damage and forms tumour
what are the classes of REGULATORY genes that target genetic damage
- growth PROMOTING ONCOGENES
- growth INHIBITING TUMOUR SUPPRESSOR GENES
- genes that REGULATE APOPTOSIS
- genes involved in DNA REPAIR
carcinogenesis is a single or multi step process
carcinogenesis occurs at which levels
multi step
occurs at PHENOTYPIC and GENETIC levels
