principles of neoplasia Flashcards
lecture 35
define atrophy
the diminution of growth due to a decrease in the size or number of the cells of a tissue
define hypertrophy
the increase in the size of an organ or tissue due to an increase in the size of the cells
define hyperplasia
an increase in the size of an organ due to an increase in the number of component cells. it persists only as long as its cause
what extrinsic factors control tissue integrity
1 - ligand receptor competence factors, allow it to enter the cell cycle
2 - physical interactions with the ECM
3 - cell cell adhesion
4 - commitment factors (hormones and ligands) allow progress through cell cycle
what protein families regulate cell cycle
1 - cyclin dependent kinases (CDKs)
2 - cyclins
- regulated by cyclin dependent kinase inhibitors (CKIs)
describe G1
- high metabolic activity, much replication.
- duration depends on external factors
- contains checkpoint for commitment to mitosis and after this the cell is independent of external factors
3 cell cycle options in G1
1 - replicate
2 - enter G0
3 - terminally differentiate and loose the ability to replicate
3 classifications of cells
1 - permanent cells - terminally differentiated like neurons and striated myocytes
2 - conditional renewal populations - in G0, can enter G1 following loss or injury or raised funciton
3 - continually self renewing - replace the terminally differentiated pool
which populations of cells contain - stem cells, transit amplifiers, terminally differentiated?
skin, gut, urinary, genital, bone marrow, lymphoid
process of intestine epithelial renewal?
slowely dividing stem cell compartment at the bottom of a crypt.
- rapidly dividing transit amplifying cells
- non dividing, fully differentiated cell at the top.
process takes 3 - 5 days. apoptosis at the top of the villus.
an example on why extracellular support is needed for cell function?
in most tissues the position of the cell is critical for the retention of the stem cell phenotype eg bone marrow stem cells depend on the stromal cells.
what are the key characteristics of stem cells?
1 - undergo renewing mitotic divisions
2 - the number of daughter cells that retain the stem cell phenotype is strictly controlled eg wounding
3 - the stem cell pool is replenished but not expanded.
define metaplasia
the replacement of one differentiated cell type with another
when does metaplasia ususally occur?
almost always a response to persistent injury, commonly glandular epithelium to a squamous one. is reversible if the injurious stimulus is removed.
2 particular sites - exposure of bronchial epithelium persistently to tobacco smoke
- exposure of endocervix of the uterus to acid pH, infection, semen. leads to squamous metaplasia.
what is dysplasia?
part of the spectrum of changes of preinvasive neoplasia. they do not necessarily revert to normal when the stim is removed.
morphology of dysplasia
1 - regular organised appearance of the epithelium disturbed by variations in shape and size of the cells
2 - increased nucleus to cytoplasm ratio
3 - pleomorhpism - irregularity with variation in nuclear size, shape, chromatin staining.
4 - hyperchromatic nuclei
5 - increased mitosis
6 - distortion of the proliferating vs non-proliferating compartment
define tumour
classically defined as a swelling but generally speaking is referring to a neoplasm
define a neoplasm
an abnormal mass of tissue, the growth of which exceeds and is uncordinated with that of the normal tissue that persists in the same excessive manner after the stimulus is removed.
- they are ireversible
the hallmarks of cancer vs neoplasia
the ability to invade and metastasise. these tumours are malignant
define benign neoplasm
they proliferate and divide but do not invade surounding tissues. are relatively predictable and usually cause symptoms by compression or obstruction or excessive hormone production.
symptoms and signs of destructive invasive growth by cancers
- blood loss
- pressure and destruction of adjacent tissue
- obstruction or constriction of flow in vital organs.
- metabolic effects such as cachexia (sig weight loss 1-3 stone) or specific tumour products ie T3,T4.
7 neoplastic shapes
sessile polyp pedunculated polyp papillary fungating ulcerated annular
benign vs malignant characteristics
B - intact surface, exophytic growth, homogenous cut suface, cicumscribed or encapsulated edge. low mitotic rate.
M - heterogenous cut surface due to necrosis, ulcerated surface, endophytic growth, vascular permeation, irregular infiltrative edge. poorly demarcated. rapid growth. hyperchromatic. usually aneuploid.
how is a tumour primarily described?
benign/malignant and cel/tissue of origin
what does -oma mean?
indicates a tumour or neoplasm
papilloma
benign squamous epithelia eg skin, cervix, oesophagus
adenoma
benign glandular epithelium eg colon, breast, ovary.
lipoma
benign connective tissue from adipocytes
fibroma
benign connective tissue from fibrocytes
chondroma
benign connective tissue from chondrocytes