Flashcards in Neoplasia 6 Deck (13):
TUMOUR SUSCEPTIBILITY IN DOGS
MALIGNANT HISTIOCYTOSIS- Bernese Mountain Dog
DISSEMINATED HISTIOCYTIC SARCOMA- Several breeds
OSTEOSARCOMA- Giant breeds, boxer, GSD, rottweiler
MAST CELL TUMOUR (SKIN)- Boxer, bulldog, retriever.
DIAGNOSIS OF NEOPLASIA
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.
-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.
FEATURES OF MALIGNANCY
Look for these in a biopsy.
-High mitotic index/abnormal mitoses
-High nucleus to cytoplasm (N:C) ratio
-Absence of encapsulation
-Lack of differentiation
DIFFERENTIALS FOR CANINE ROUND CELL TUMOURS
-Canine cutaneous histiocytoma
-Mast cell tumour
-(Transmissible venereal tumour, TVT)
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.
Tumour grading- an assessment of degree of differentiation- high/medium/low. eg. Mast cell tumours, grade I, II, III.
-Degree of necrosis
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.
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.
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.
ANIMAL MODELS OF CANCER- NATURALLY OCCURRING
-> studies in viral induction
Canine models are becoming increasingly useful.
Genome characterised, rapid development of metastatic disease- particularly osteosarcoma, lymphosarcoma.