What are the key features to distinguish neoplasia?
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Define neoplasia
- uncontrolled proliferation of cells- proliferation continues in abscence of inciting cause neoplastic cells originate from a single cell (has undergone mutation and lost the ability to control its division)
Define hyperplasia
Proliferation of cells that stops when inciting cause is removed
What does current research show neoplastic cells may be ?
2 types of cells not just monoclonal
How do benign tumours grow? How do they appear clinically and pathology?
- slowly by expansion- well demarkated from surrounding tissue (may be compressed)- surrounding tissue capsule- freely mobile on palpation- uniform cut surface (may contain cysts) - little hamorrghage or necrosis
What is a haemangioma?
benign tumour of the blood vessel wall endothelium
Microscopic features of benign tumours?
- cells similar to tissue of origin- well organsied - share the functional purpose of tissue- contained in capsule- cells not mitotically active - little evidence of 2* change (haemorrhage or necrossi)
Characteristics of malignant tumours
- grow by invasion- not encapsulated- not mobile on palpation - complete removal difficult- often ulcerate if on skin or mucosa- recurs after removal- surface necrosis and naemorrhage- METASTASIS
Which breed are predisposed to hamemangiosarcoma?
GSD
Microscopic feeatures of malignancy?
- pleioporphism (different looking cells)- anisokaryosis (differnet sized nuceli?)- ^ nucleus:cytoplasm ratio- normal/abnormal mitoses- loss of cohesiveness and structure- malignat fusion -> syncitia- 2* changes (necrosis inflamm etc.)- not encapsulated/extending beyond the capsule
Name some benign tumours of epithelial origin
> surface or non-glandular epithelia = papilloma> glandular epithelia = adenoma
Name the main types malignant tumours of epithelial origin
> epithalial = carcinoma> glandular epithelia = adenocarcinoma
What is the suffix for mesenchymal origins?
- benign = -oma- malignant = -sarcoma
What is the exception to the -oma tumour rule?
- Granuloma - not a tumour! Just chronic inflammation
What are lymphomas?
- tumouro fthe lymphoid system = MALIGNANT!
What are melanomas?
Benign OR malignant tumour or melanocytes
What are mastocytomas?
Can be benign or malignant mast cell tumours
What are leukaemias?
tumours derived from cells of bone marrow, circulate in the blood
What are sarcoids?
low grade fibrosarcomas commonly seen in horses (bovine papillomavirus infection)
What are the 4 routes of metastasis? Which tumours spread this way?
> lymphatic- carcinoma- LNs draining tumour contain 2* deposits > vascular - sarcoma- tumour seeds widely to internal organs (liver and lungs, multiple 2*) >trans-cavity- mesothelioma or ovarian neoplasia- spread acorss serosial surfaces eg. effusion > local - multiple tumour types - spread along fascial planes
WHat are multicentric tumours?
eg. lymphoma- difficult to determine primary site
Which malignant tumours are most likely to metastasise rapidly and constantly?
- tonsillar carcinomas- pancreatic carcinomas- osteosarcomas- oral and digital melanomas- mammary carcinomas (cats)
Which malignant tumours metastasise slowly or rarely?
- squamous cell carcinomas- fibrosarcomas > invade locally, recurr but not liekly to metastasise
How may immunohistochemistry be used to dx tumour?
- poorly differentiated tumours cannto be IDed on morphological grounds alone- cell surface markers eg. cytokeratin, B/T cell lymphomas
