ICS week 2 Flashcards
what are the characteristics of neoplastic cells in a tumour? what do they do/secrete? how can these secretions detect tumours?
- they reproduce (to a variable extent) the growth pattern and synthetic activity of the parent cell of origin
- may still synthesise and secrete cell products e.g. collagen, mucin or keratin, which may accumulate in the tumour where they are recognisable histologically
- cell products secreted into the blood can be used to monitor tumour growth and effects of therapy
what is the function of stroma in a tumour and what is it?
- connective tissue framework
- provides mechanical support, intercellular signalling and nutrition to the neoplastic cells
what is a desmoplastic reaction?
the process of stroma formation when it is particularly fibrous
what causes stroma formation?
- induction of connective tissue fibroblast proliferation by growth factors elaborated by tumour cells
what are cancer-associated fibroblasts? what do they do?
fibroblasts with slightly altered properties in a tumour
- secrete a matrix
- matrix gives mechanical support to neoplastic cells and has nutritive, intercellular signalling and enzyme-secreting properties
what do stromal myofibroblasts do in tumours?
- may be abundant, esp. in breast cancers
- their contractility is responsible for puckering and retraction of adjacent structures
what does growth of a tumour depend on? when does growth cease?
- its ability to induce blood vessels to perfuse it
- unless it’s permeated by a vascular supply, its growth is limited by the ability of nutrients to diffuse into it
- tumour ceases expanding when the nodule has a diameter of no more 1-2 mm
what can be used to treat inflammation?
- prostaglandin synthetase inhibiors (e.g. aspirin, ibuprofen)
- corticosteroids, NSAIDS, monoclonal antibodies: bind to DNA to upregulate inhibitors of inflammation, downregulate mediators of inflammation
what induces angiogenesis in tumours? what opposes this action?
vascular endothelial growth factor
- opposed by factors such as angiostatin and endostatin
what would suggest a host immune reaction to a tumour?
lymphocytic infiltrate of variable density
what is the gross appearance of a tumour on a surface?
can be described as sessile, polypoid, papillary, exophytic/fungating, ulcerated or annular
what are examples of the behaviour of a tumour correlating with its gross appearance?
- polypoid tumours are generally benign
- ulceration is associated with destructive invasive behaviour (key feature of malignancy)
how can ulcerated tumours be distinguished from non-neoplastic ulcers?
ulcerated tumours tend to have heaped-up irregular edges
what is a key characteristic feature of benign epithelial tumours?
- circumscription by a clearly defined border
- some malignant connective tissue tumours are also well circumscribed
why are tumours usually firmer than the surrounding tissue? what does this cause?
- stromal fibrosis
- causes a palpable lump in accessible sites
why are cut surfaces of malignant often variegated?
due to areas of necrosis, haemorrhage, fibrosis and degeneration
cut surfaces of which malignant tumours may seem uniformly bland?
- lymphomas
- seminomas
how do neoplasms differ histologically from their corresponding normal tissue?
- loss/reduction of differentiation
- loss/reduction of cellular cohesion
- nuclear enlargement, hyperchromasia and pleomorphism
- increased mitotic activity
what is the process of tumour angiogenesis?
- transformation of a single cell
- growth of an avascular tumour nodule with a diameter of 1-2 mm. limited by ability of nutrients to diffuse into it
- production of angiogenic factors stimulates proliferation and ingrowth of blood vessels; tumour growth is supported by perfusion
- the tumour eventually outgrows its blood supply and areas of necrosis appear, slowing growth
what are the different tumour shapes?
- sessile
- pedunculated polyp
- papillary
- exophytic/fungating
- ulcerated
- annular
which tumour shapes are more likely to be benign/malignant?
benign:
- sessile, polypoid and papillary
malignant:
- exophytic/fungating, ulcerated or annular
where are annular tumours common?
large bowel, often cause intestinal obstruction
how are tumours classified, and why is classification important?
- according to behaviour and histogenesis
- precise classification is important for planning effective treatment
what is behavioural classification?
divides tumours into benign and malignant
- main thing that distinguishes them is invasion