T11 Flashcards
Define hyperplasia
Enlargement of an organ, or a tissue within it, due to an increase in the number of cell
What is an example of hyperplasia?
growth of breast in pregnancy
Define metaplasia
Reversible change in the character of a tissue from one mature cell type to another
What is an example of metaplasia?
resp. epithelium replaced with squamous epithelium in bronchi of smokers
Define dysplasia
Abnormal growth and differentiation of a tissue; in epithelia, often a feature of the early stages of neoplasia
Define neoplasia
Autonomic, uncontrolled development of new but useless tissue that stimulates the tissue of origin that continues to grow after removal of initiating factor. Loss of normal cell growth control through mutations. Can be benign or malignant
What is neoplastic transformation?
Neoplastic transformation of a single cell results in the growth of a tumour
Describe the process of tumour angiogenesis
Nodule, limited by the ability of nutrients to diffuse into it, to a diameter of 1-2 mm. Production of angiogenic factors stimulates the proliferation and ingrowth of blood vessels, enabling tumour growth to be supported by perfusion. Eventually, the tumour outgrows its blood supply, and areas of necrosis appear, resulting in slower growth.
What happens when oncogenes / tumour suppressor genes are mutated?
Uncontrolled cell growth and tumor formation
What are the factors relating to tumour incidence?
- Age
- Gender
- Geographic
- Genetic
- Environmental (carcinogens)
- Environmental factors and genetic predisposition
What is the parenchymal structure of tumours?
- Neoplastic cells
- Reproduce to a variable extent the grown pattern and synthetic activity of parent cell of origin.
- Can continue to synthesise + secrete cell products (accumulate in cell often or secreted into blood)
What is the stromal structure of tumours?
- Tumour microenvironment
- Supportive connective tissue and blood vessels
What are the macroscopic morphological patterns of neoplasia?
- Sessile: E.g. flat adenoma in GIT
- Pedunculated polyp/polypoid: E.g. adenomatous polyp in colon
- Papillary: fingerlike e.g. villous adenoma
- Exophytic/fungating: E.g. colon carcinoma
- Ulcerated: E.g. colon carcinoma
- Annular/stenosing: E.g. usual in viscus, e.g. GIT (colon carcinoma)
List characteristics of a benign tumour
Slow growth Well differentiated Localized No metastases Not fatal
List characteristics of a malignant tumour
Rapid growth Less differentiated Infiltrating, destructive, poorly circumscribed Often metastases Often fatal
Explain the principle of histogenetic classification
- Specific cell/tissue of origin of an individual tumour
- Tumours are named according to the tissues from which they arise and of which they consist
What is histological grading?
The degree of differentiation. Extent to which tumour resembles histologically its cell/tissue of origin determines tissue grade.
What is tumour differentiation?
- Describes how much or how little a tumour tissue looks like the normal tissue it came from
- Benign tumours: well differentiated
- Malignant tumors: variable grade of differentiation
What are the different grades of differentiation?
well, moderate, poor, anaplastic
What is anaplasia?
Poor differentiation/no differentiation
What suffix do tumours have?
-oma
Name the principles of benign tumour nomenclature
- Benign tumours are either papillomas or adenomas
- Benign connective tissue tumours have prefix denoting cell of
origin
Name the principles of malignant tumour nomenclature
- Malignant epithelial tumours are carcinomas
- Malignant connective tissue tumours are sarcomas
What suffix do neoplasm of blood cells have?
-aemia
Name and give examples of mesenchymal tumours
- Fat: lipoma
- Cartilage: chondroma
- Striated muscle: rhabdomyoma
Name and give examples of epithelial tumours
- Glandular epithelium: adenoma
- Squamous epithelium: squamous carcinoma
- Glandular epithelium: adenocarcinoma
What is carcinoma in situ?
- Epithelial neoplasm exhibiting all cellular features associated with malignancy but which has not yet invaded through the epithelial basement membrane separating it from potential routes of metastasis – blood vessels and lymphatics
- Complete excision cures patient
- Preceded by dysplasia
What is local infiltration?
- Infiltrate adjacent structures / organs / lymphatics /
blood vessels - Ulceration = haemorrhage of infection
- Obstruction e.g. GIT by a tumour with an annular and
stenosing appearance
What is metastasis?
process of formation of distant secondary tumours
What is a teratoma?
-Neoplasm of germ cell origin that forms cells representing all 3 cell layers of embryo
- Can be mature, immature, malignant
- Benign may contain teeth and hair, respiratory epithelium, cartilage, muscle, neural tissue, etc.
- Malignant tumour represent immature and less identifiable ectoderm, mesoderm and endoderm.
- Occur most often in gonads: ovarian = benign and cystic, testis = malignant and solid
- Sometimes originates in midline
What is a blastoma?
- Malignant embryonic tumour
- Occur in young children < 5 yrs
- Bear embryological appearance of the organ in which it occurs
Name examples of blastomas
- Nephroblastoma/Wilms tumour in kidney
- Retinoblastoma in eye
- Neuroblastoma in adrenal medulla - Hepatoblastoma in liver
What are mixed tumours?
Non-organoid combinations of mature tissue types (cell types) of 1 germ cell layer
Name examples of mixed tumours
- Mixed parotid tumour (pleomorphic salivary adenoma)
-Fibroadenoma of breast, lobular tumour consisting of
epithelium-lined glands or clefts in a loose fibrous tissue matrix
What is a neuro-endocrine tumour?
Diffuse endocrine system, derived from hormone-secreting cells
Name examples of neuro-endocrine tumours
- medullarycarcinoma
- insulinoma
- carcinoid tumours
What is a carcinosarcoma?
malignant tumors that consist of a mixture of carcinoma (or
epithelial cancer) and sarcoma
What is a hamartoma?
- Tumour-like lesion, growth coordinated with individual, lacks autonomy of true neoplasm
- Benign, consists of 2/more mature cell types found in organ of origin
Name examples of a hamartoma
amartoma of lung
pigmented naevi of skin/moles
What is a cyst?
Epithelium-lined fluid-filled space
Name examples of non-neoplastic cysts
parasitic cyst; congenital cyst; retention cyst; implantation cyst
Name examples of neoplastic cysts
Cystadenoma
Cystadenocarcinoma
Briefly explain the principles in respect of tumour cell biology with reference to genetic (DNA) aspects
- Polyploidy (too many copies of diploid DNA) & aneuploidy (abnormal number of chromosomes in a cell) = pleomorphism = increased tumour aggressiveness
- Karyotypic abnormalities (chromosome abnormality/ translocation /rearrangement)
- Mutations of oncogenes / tumour suppressor genes
Briefly explain the principles in respect of tumour cell biology with reference to mitotic and apoptotic activity
- Often more mitoses, Abnormal mitoses
- Sometimes loss of apoptosis (cell loss)
Briefly explain the principles in respect of tumour cell biology with reference to metabolic abnormalities
- No specific abnormalities
- Cell surfaces change: loss of cohesion - Abnormal gene expression
