Using the pathologist Flashcards
Define neoplasia 3
- uncontrolled cell proliferation
- proliferation continues in absence of inciting cause
- neoplastic cells originate from single cell which has lost ability to control its division
What is tumour classification based on?
clinical and pathological features
What are gross features of benign tumours
growth by expansion low to moderate growth rate tumour well demarcated (compresses surrounding tissue) smooth in gross outline surrounding CT capsule freely mobile on palpation homogenous cut surface (cystic in glandular tissue) little haemorrhage or necrosis surgical removal often easy no recurrence if completely excised no metastasis
What are microscopic features of benign tumours?
very similar to tissue of origin
well organised
benign endocrine tumours can be functional
surrounding CT capsule - tumour doesn’t broach this
few or no mitoses
generally no haemorrhage or necrosis
Gross features - malignant tumours
growth by invasion
not encapsulated
not usually mobile on palpation
complete removal often difficult
often recurs after excision
often ulcerate if on skin or mucosal surface
secondary changes - internal necrosis and haemorrhage
can metastasise to local LNs and lungs (often)
Microscopic features - malignant tumours
pleomorphism anisokaryosis increased nuclear: cytoplasmic ratio prominent nucleoli normal/abnormall mitoses loss of cohesiveness and structure syncytia secondary changes - necrosis, fibrosis, inflammation usually not encapsulated
Define anisokaryosis
variable size and shape of nucleoli
Define pleomorphism
variable cell size and shape
Define papilloma
benign, surface epithelia
Define adenoma
Benign tumour, glandular epithelia
Define thyroid adenoma
glandular epithelia (benign) tumour prefixed by the tissue of origin
Define carcinoma
malignant, epithelial origin
Define adenocarcinoma
malignant tumour of glandular epithelia
Is a tumour ending in -oma benign or malignant?
Benign (except granuloma - chronic inflammation). Tumours with the ending -sarcoma are malignant
Define lymphoma
tumours of lymphoid system
usually malignant
Define melanoma
Tumour of melanocytes
some benign, other malignant (malignant melanomas)
Define MCT (mastocytoma)
tumour of mast cells
vary in degree of malignancy
Define leukaemia
tumours derived from cells of BM which then circulate in the blood
Define teratoma
germ cell tumours with elements of ectoderm, endoderm and mesoderm
Define sarcoid. Cause?
low grade fibrosarcoma
commonly seen in the skin of horses (caused by BPV)
How can tumours metastasise? 4
lymphatic
vascular
trans-cavity
local
What is lymphatic spread typical of?
Carcinomas
Tumour spreads across serosal surfaces (may be associated with effusions)
Outline vascular spread
Typical of sarcoma
Tumour seeds widely to internal organs (liver and lungs)
Outline trans-cavity spread
Typical of mesothelioma
Less common
Spreads across serosal surfaces
Outline local metastasis
May occur in multiple tumour types
Less common
Spread along fascial planes
Define multicentric tumour
where it is difficult to determine a primary site as multiple tumours are present at first presentation
List some malignant tumours that metastasise rapidly and constantly
tonsillar carcinomas pancreatic carcinomas OSA oral and digital melanomas mammary carcinomas (cats)
List some malignant tumours that metastasise slowly or rarely
SCC = tend to invade extensively before undergoing metastasis Fibrosarcomas = tend to invade and therefore recur at the site of excision, without undergoing metastasis
List 4 examples of IHC markers and their uses
epithelial, mesenchymal, TC and BC markers
Cytokeratin - epithelial marker - carcinoma
Vimentin - mesenchymal marker - sarcoma
CD3 - TC marker - TC lymphoma
CD79a - BC marker - BC lymphoma
What is tumour grading?
measure of differentiation
How can tumours be graded? 4
Light microscopy (SCC - keratin production)
Immunophenotyping (lymphoma)
Detection of genetic mutations (lymphoma)
Use of proliferation markers (MCTs)
What is cytogenetics?
A method of tumour grading where the specific mutation is detected - this is the standard practice for human lymphomas.
What is Ki-67?
A proliferation marker that can be detected for tumour grading. Particularly useful for MCT grading in dogs.
Define clinical audit
to determine why a therapy might have failed
How can a pathologist help a clinician
Obtain definitive Dx or shortlist Prognosis estimate Treatment plan Client education Clinical audit
What should a biopsy report contain? 5
Signalment and clinical history
Gross description
Clear and concise histological description
Diagnosis or likely DDx
Comments on biological behaviour and prognosis with recommendations for monitoring/treatment and client education.
When should you call the path lab? 4
If path diagnosis doesn’t fit with clinical findings
Before tissue collection in unusual cases
Urgent results needed
Follow-up appreciated
What does the pathologist require?
Representative sample
Correctly submitted
Full clinical history
How can a sample be taken?
Incisional - punch, trucut, endoscopic or wedge#
OR
Excisional
Include margin of normal tissue
Avoid necrotic and cavitated areas (usually central, except bone tumours where area of max lysis is useful)
Mark margins of interest (suture tag or indelible dye)
Identify samples from different sites
[Imaging guidance]
How do you submit a sample?
Large volume of neutral buffered formalin (4:1 or 10:1)
<2cm in longest dimension
Larger specimens unfixed if close to lab
Royal Mail guidelines for path. specimens
Label - indelible, practice, owner, animal, site, difference between sites, normal and abnormal sites (esp skin biopsies)
What should be included on the full clinical history?
Signalment Clinical History Previous lab results previous therapy Clinical Dx or DDx Special considerations (forensic, legal) Gross description/photo
