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Flashcards in Neoplasia 6 Deck (13):
1

TUMOUR SUSCEPTIBILITY IN DOGS

LYMPHOMA/SARCOMA- Boxers
MALIGNANT HISTIOCYTOSIS- Bernese Mountain Dog
DISSEMINATED HISTIOCYTIC SARCOMA- Several breeds
HEMANGIOSARCOMA- GSD
OSTEOSARCOMA- Giant breeds, boxer, GSD, rottweiler
MAST CELL TUMOUR (SKIN)- Boxer, bulldog, retriever.

2

DIAGNOSIS OF NEOPLASIA

Cytology
Biopsy

3

CYTOLOGY

Where do we get cells from?
-Cells shed naturally in to body fluids- urine, CSF, fluid in pleural or peritoneal cavities.

-Cells obtained by exfoliation- tracheal wash, prostatic wash

-Cells aspirated by needle- blood, bone marrow, needle aspiration of solid tumours.

4

BIOPSY

-NEEDLE- Core of tissue 1-2mm wide, 2cm long.

-ENDOSCOPIC- Small forceps collect smal (2-3mm) fragments. GI tract, respiratory tract, genitourinary tract.

-INCISION- Sample of lesion removed with a scalpel.

-EXCISION- Entire tumour removed.

5

FEATURES OF MALIGNANCY

Look for these in a biopsy.
-Abnormal morphology
-Invasion/metastasis
-High mitotic index/abnormal mitoses
-High nucleus to cytoplasm (N:C) ratio
-Absence of encapsulation
-Lack of differentiation

6

DIFFERENTIALS FOR CANINE ROUND CELL TUMOURS

-Lymphoma/sarcoma
-Canine cutaneous histiocytoma
-Mast cell tumour
-Plasmacytoma
-(Transmissible venereal tumour, TVT)

7

LYMPHOMA/LYMPHOSARCOMA

Sheets of round cells with nucleus (open faced, nucleoli visible) and cytoplasm visible.

Lymphosarcomas can be typed using immunohistochemistry- CD3 detects T cells.
CD79a detects B cells.
Positive is brown.

8

CLINICAL ONCOLOGY

Tumour grading- an assessment of degree of differentiation- high/medium/low. eg. Mast cell tumours, grade I, II, III.

-Mitotic rate
-Degree of necrosis
-Location
-Invasiveness

9

MAST CELL TUMOURS

OLD grading method:
PATNAIK GRADE I- Well differentiated, good prognosis with complete excision.
PATNAIK GRADE II- Wide range of possible behaviours, from resolution with excision to widespread metastasis. Proloferation markers- Ki67.
PATNAIK GRADE III- Malignant, invasive, metastatic.

Prognosis- >1.8% positive on Astra blue stain gives a poor prognosis.

10

MAST CELL TUMOURS- NEW GRADING METHOD

HIGH GRADE- If one of the following applies:
-Greater than 7 mitotic figures per 10 HPF high power field)
-Greater than 3 multinucleated cells per 10 HPF
-Greater than 3 bizarre nuclei per 10 HPF
- >10% karyomegalic cells.

11

TUMOUR STAGING

Uses the TNM method:
T- Primary tumour size/local invasion
N- 'Nearby' (regional) lymph node involvement
M- Extent of metastasis.

TNM Stage I- Single node involvement
Stage II- Multiple nodes in a regional area
Stage III- Generalised lymphadenopathy
Stage IV- Liver and/or spleen involvement
Stage V- Bone marrow, blood and/or non lymphoid organ involvement.

Substage a- Without clinical signs of disease.
Substage b- With clinical signs of disease.

Then, we can make a therapeutic plan and make a prognosis.

12

ANIMAL MODELS OF CANCER- NATURALLY OCCURRING

-Avian leukosis
-Bovine lymphosarcoma
-Feline leukaemia
-> studies in viral induction

Canine models are becoming increasingly useful.
Genome characterised, rapid development of metastatic disease- particularly osteosarcoma, lymphosarcoma.

13

ANIMAL MODELS OF CANCER- EXPERIMENTALLY INDUCED

Aim to produce rapid, reproducible induction in large population.
Mouse has a well defined genome, and genetically engineered mice are easily producable, with specific genes activated or suppressed.
-Transgene- an introduced gene.
-KO- lack of normal functioning gene.