Introduction to veterinary oncology Flashcards
Is cancer a major cause of death in animals?
Yes - animals are living longer
USA study - 45% dogs >10 years old died of cancer
What are the major DDx for cnacer?
Inflammatory lesions - abscess, granuloma
Haematoma
Seroma
Cyst
What history/clinical evidence should you consider when deciding if a mass is cancer or not?
How long has it been present?
Is it growing and how rapidly?
Is it hot, erythematous or painful? (might indicate inflammatory lesion but could still be neoplasia)
Solid or fluid filled? (fluid could indicate abscess, seroma, haematoma, cysts - but could still be a tumour with necrotic centre)
Is it well-defined or ill-defined? Is it fixed to underlying tissues? (ill-defined lesion or fixation might indicate infiltrative growth or tumour)
What is the best way to go about making a diagnosis?
TAKE SAMPLES!
Cytology - FNA
Histopathology
What information does cytology provide you?
- Quick, cheap, easy
- Usually can distinguish inflammatory vs. neoplastic (inflammatory contains neutrophils or mixed cell population. Neoplastic lesions have one predominant cell type).
- Cell type and morphology (helps determine if benign or malignant)
- Useful to analyse effusions and BM
What information does cytology NOT provide you with? 4
Tissue architecture
Mitotic index
Invasion - vasculature/lymphatics
Tumour grade
How do you perform histopathology?
Requires biopsy under GA or sedation
Incisional, excisional, tru-cut, Jamshdi or trephine biopsy
How does histopathology tell you?
Gold standard for Dx
Differentiate inflammatory and neoplastic
Cell type and morphology
AND:
Tissue architecture (is it disrupted?)
mitotic index
invasion - vasculature/lymphatics/surrounding tissues
degree of necrosis
These features help decide if benign/malignant and sometimes assign a grade.
What should you do if a lesion is neoplastic?
- Determine cell/tissue of origin (epithelial, mesenchymal or round cell) - cytology or histopathology
- Special stains/IHC or additional techniques (flow cytometry) are sometimes required to make/refine Dx (e.g. to determine whether a lymphoma is a BC or TC origin)
Why is a definitive diagnosis essential?
Different tumour types have different biological behaviour and have different treatments.
Are lipomas and meningiomas benign or malignant?
Both benign
What is a tumour grade?
Assigned by pathologist
Helps predict behaviour of certain tumour types (MCT and STS)
Involves assessment of: mitotic index degree of cellularl differentiation invasion - surrounding tissues/BVs/ lymphatics Amount of necrosis etc
Categorised as low, intermediate or high
When are numbers assigned to tumour grade?
Some specific cancers:
Patnaik grading system - MCT (1= low to 3=high)
Kiupel grading system (new) - MCT - 2 categories (low and high)
Why is grading important?
Can affect treatment plan and prognosis
Important for communication
What is clinical staging?
Performed after cancer Dx = assesses the extent of disease in patient, performed by clinician ASSESSMENT OF: primary tumour drainage LNs screening for distant metastatic disease
TNM system often used (T= primary tumour, N = node, M = distant metastasis)
What is assessed in the T part of the TNM system?
T = primary tumour Size Mobility Relationship to surrounding tissues Presence/absence of ulceration/erythema
Physical palpation in many cases but may require imaging or endoscopy assessment
Sometimes the T,N and M are given a numerical or alphabetical suffix reflecting the extent of the involvement.
What is assessed in the N part of the TNM system?
Assess drainage LNs for: size mobility relationship to surrounding tissues (mobile/fixed) texture consistency
Imaging might be required (internal LNs)
FNA (or biopsy) frequently used to assess if LN metastasis is present or not (nodes can be normal size yet affected by metastasis. Enalarged nodes can be metastatic or hyperplastic).
What is assessed in the M part of the TNM system?
History and PE give clues
Usually assessed via imaging
Lungs most common site for distant metastases (SA) –> thoracic radiographs (ideally inflated, 3-views) or CT (this is more sensitive for detecting metastases)
Other sites can be important - liver, spleen, kidneys, heart, skin, bones, CNS
FNA/biopsy maybe needed to confirm metastasis
Outline primary tumour classification (T)
T1 = 5cm diameter
Outline regional node classification (N)
N0 = histologic or cytologic - no metastasis N1 = histologic or cytologic - metastasis present
Outline distant metastasis classification (M)
M0 = no distant metastasis present M1 = distant metastasis present
When is the TNM classification not used?
For systemic or multicentric diseases - e..g. lymphoma present in a disseminated form and the TNM system is not appropriate. Lymphoma is staged according to the organ systems involved.
Outline the WHO system for staging canine lymphoma
1 = involvement limited to a single node or lymphoid tissue in a single organ (excluding BM)
2= involvement of more than one LN in a regional area (+/- tonsils)
3= generalised LN involvement (both sides of diaphragm)
4 = liver and/or spleen involvement (+/- stage 3)
5 = manifestation in the blood and involvement of BM and/or other organ systems (stages 1-4)
Differentiate tumour grade and tumour stage.
GRADE - describes how abnormal the tumour cells and tiissue look under the microscope. Indicative of ho wquickly a timour is likely to grow and spread
STAGE - refers to the size and/or extent/reach of the original/primary tumour and whether or not cancer cells have spread in the body
