oncology 3 Flashcards
Describe & discuss the different methods of diagnosis for mast cell tumours (MCT)
- which is usually best? how can we tell what we are looking at? what possible negative effect?
- FNA
> cytology usually diagnostic
>characteristic appearance - mononuclear, granules
=> graulation varies (often with grade)
=> stain can affect ability to see granules
>may produce inflammatory reaction, bleeding after aspiration
=> “Darier’s sign” due to degranulation, release of contents such as heparin, histamine
=> Premedication with diphenhydramine (Benadryl) if concerned
() - incisional biopsy
- excisional biopsy
what stain for MCT?
wright-giemsa is good
- diff-quick not great
MCT incidence and signalment
– 7‐21% of all skin tumours
– 11‐27% of all malignant tumours
()
mean age = 9 years
– BUT there is a WIDE AGE RANGE
()
- many breeds predisposed: Boxer, Boston, Lab, pug, golden…
MCT - canine, location
- Cutaneous and subcutaneous most common
- 50% trunk
- 40% extremity
- 10% head and neck
- visceral - metastatic
> spleen, liver, kidney
MCT clinical signs
Mass
* solid skin mass
> may ulcerate, swell, or be pruritic
* Lipoma‐like
* Subcutaneous
* Mucosal (oral)
()
Paraneoplastic effects
- edema, shock
- GI signs
- bleeding tendencies
- ulceration, wound dehiscence
- pruritis
** systemic illness common with metastatis disease**
contents of mast cells
- Histamine
- Heparin
- Eosinophilic chemotactic factor
- Proteolytic enzymes
MCT Location, Appearance, Clinical Signs
- most frequently dermal or subcutaneous
- most solitary
- usually raised, may be ulcerated
- may be solid, soft (like lipoma), mucosal (e.g. oral)
- may have been present for long period of time
- no specific signs, but pruritis, GI ulceration possible, bleeds
> Systemic illness common with metastatic disease - CAN LOOK LIKE ANYTHING
clinical staging of MCT - how do we do it?
- diagnosis: FNA ± biopsy (for histology grading)
()
Staging:
– CBC & biochemical profile
– Cytology of draining LN
– Abdominal ultrasound + cytology
()
– ± Bone marrow
– ± Coagulogram (PT, PTT, FDP)
cancer stage vs grade
- a grade describes the appearance of cancer cells and tissue
- a stage explains how large the primary tumor is and how far the cancer has spread in the patient’s body.
what does it mean if we find mast cells in the liver, spleen, or lymph nodes when trying to stage the MCT?
- presence of mast cells in the liver or spleen does NOT equal metastatic mast cell tumour
- LN shouldn’t have large numbers of mast
cells in a normal population
use of CT for MCT staging, etc.
- useful for staging abdomen on large dog
- useful to evaluate lymph node
- useful to plan surgery
what are the stages for a mast cell tumor and what do they mean?
- Staging (modified from WHO)
> Stage I: single skin tumour
> Stage II: single skin tumour + regional lymph node (LN)
> stage III: multiple skin tumours or single large deep tumour ± regional LNs
>Stage IV: distant spread (blood or bone marrow)
()
> a: without systemic signs
> b: with systemic signs - Prognosis worse with increasing stage
- Multiple tumours may not have a worse prognosis
are multiple MCT common? related to one another? how should we approach the 2nd tumour?
- 20-25% of dogs with a MCT will get a 2nd MCT during their lifetime
- unrelated to 1st MCT
- likely predisposition
- needs to be treated like a new primary and not as a metastatic site
MCT diagnostic / staging steps - how do we decide what to do next?
- Anatomic site amenable to wide surgical excision?
> if yes… - negative prognostic factors present?
> if no… - excise with wide surgical margins. submit for grade and margin
> if complete margins, intermediate or low grade, and no negative prognostic indicators - routine follow-up
()()()
- if not amenable to wide surgical excision
OR
- if negative prognostic factors present
OR
- if poorly differentiated, highly proliferative, or surgical margins incomplete…
> Expand diagnostics prior to definitive therapy: - biopsy for histologic grade (+/- KIT analysis)
- lymph node aspirate
- abdominal US +/- spleen/liver aspirate
- CBC, biochem
how do we answer: how bad is it? for MCT
- diagnosis: FNA
- biopsy for histo grading
MCT prognosis requires:
- histologic grade
- stage
Patniak groups for MCT grade: what are they and what criteria is considered? what are most of them?
3 groups:
> low (I): well differentiated
> intermediate (II)
> high (III): poorly differentiated
()()
Based on:
* Mitotic figures
* Differentiation
* nuclear pleomorphism
> multinucleated cells, bizare nucleu, karyomegaly
* depth?
()()
vast majority will get a grade II
> ‘high vs low’ grade II
Kiupel 2 tier system: high grade vs low grade MCT prognisis
- High Grade associated with a significantly shorter time to metastasis and survival time
> low grade > 2 years
> high grade < 4 months
markers of proliferation other than mitotic index? what is a negative prognostic factor for MCT?
- the higher the marker the worse the tumor
> AgNORs
> Ki-67
> PCNA
> Doubling time
()
-rapid tumor growth and sudden appearance negative prognostic facotr
mutation in what gene affects MCT prognosis? what does it do?
c-kit
> encondes KIT, a tyrosine kinase receptor that binds stem cell factor, promoting the development/ function of mast cells
canine MCT prognosis overall depends on:
- grade
- extent (clinical stage)
- tumour location
> subungual, oral, mucous membranes mucocutaneous jct worse
> preputial, scotal worse
> SC better prognosis - breed
> boxer less aggressive disease - growth rate
- proliferation indices
> MI, AGNORs, PCNA, Ki-67 - recurrence
- systemic signs
- c-kit mutation
prognostic factors for canine dermal MCT
- systemic signs
- growth rate
- grade
- mitotic index
- proliferation markers
- c-kit mutation
- surgical margin
- extent (stage)
- breed
- tumor location
prognostic factors for canine subcutaneous MCT
- grading system for cutaneous not valid for these
- aggressiveness based on mitotic index
> many act benign
can you grade a MCT form cytology?
Bottom line with cytology:
If it looks bad, it probably is‐‐‐
If it doesn’t look bad, it still might be
