MCT in a beagle

Re: MCT in a beagle

Gerry Polton — Mon, 13 Apr 2015 17:28:14 GMT

In principle, narrow margins are more of a concern than wide margins. However, when the narrow (but complete) margins are married with the wartlike appearance and the low mitotic index, I think that the level of concern that we should have is low. I would reiterate my point that if you were going to do something, I would do revision surgery. That is because there is scope to believe that recurrence is a threat. But it's a low level threat.

Gerry

Re: MCT in a beagle

Robin Grimmer — Mon, 13 Apr 2015 14:06:46 GMT

Thanks very much Gerry for your detailed reply. Do you think the narrow margins in this case are an additional cause for concern?

Re: MCT in a beagle

Gerry Polton — Mon, 13 Apr 2015 10:08:05 GMT

I approach these cases looking at all of the variables which could have some bearing on prognosis. In simple terms I categorise them as issues relating to the physical appearance, issues relating to historical changes and issues relating to laboratory matters. In my head, these all carry equal weighting. So let's say, as in this case, we have a small innocuous looking lesion with a high ki-67, one kind of counters the other. Where I think I am different from other oncologists is that I would not necessarily apply greater weighting to an above threshold lab result if the combined weight of other variables appears to contradict the laboratory output. It is true that this leaves us with an acceptance of greater uncertainty. But I think uncertainty reflects our world better than binary analyses of prognostic markers.

So, in plain English, I think there is a very good chance this dog is cured. Moving forward, I would emphasise the point that we do not know that it is cured. Therefore it is appropriate to consider how we should manage the case rather than simply ignoring the problem. Options for management include: no further therapy or observations; serial rechecks and additional action if action is required, and finally, additional therapy now. All are potentially correct and owners must indicate whether they are happier doing less and risking relapse or doing more and risking iatrogenic complications and unnecessary expense. In this case I would choose serial monitoring. I would advise a six-weekly check up with you, Robin, for four checks (history and physical exam to focus on area of scar and regional lymph nodes- clip fur if necessary to examine site well and to emphasise that examination is happening, reinforcing fact that cure is not guaranteed). Thereafter a check which includes the site of the tumour excision and the regional lymph nodes can be performed when the dog is presented for annual health checks, assuming these are performed.

I will estimate the risk of relapse of metastasis as 5-10%. This is an estimate but it gives the owner a framework against which to judge whether they are happier doing stuff or not doing stuff. If the owner is happier with further therapy, the thing most likely to make a difference to overall survival in this case is, in my opinion, revision surgery.

I should add that the 5-10% thing is a number I have pulled from my gut instinct, not an official published-evidence-based number.

I hope that helps.

Gerry

Re: MCT in a beagle

Robin Grimmer — Sun, 12 Apr 2015 20:48:38 GMT

FAO Gerry:

History - small 'wart-like' lesion on skin to the right of the sternum.

Grade II MCT, prognosis good with complete excision, margins marginal. Description: one section of the submitted tissue is examined. The dermis contains a neoplastic cellular proliferation. This consists of sheets of cells that are polygonal with granular basophilic cytoplasm and oval nuclei with finely stippled chromatin and small nucleoli. Mitoses average less than 1 per 10 40x high power fields. The neoplasm has been excised with lateral margins of 3mm and deep margins of 6mm free from neoplastic cells. Comment: The histological appearance is of a grade II MCT with a low mitotic rate. Based on the histological appearance, the prognosis is likely to be good. Immunohistochemistry for Ki67 can give a more accurate forecast of how the lesion is likely to behave.

Ki67: A representative field of the tumour revealed 36 Ki67 positive mast cells out of a total of 1432 mast cells. The Ki67 index is therefore 2.51%, which indicates that the MCT would be expected to have significant potential to behave in an aggressive manner.

Re: MCT in a beagle

Robin Grimmer — Fri, 10 Apr 2015 20:49:38 GMT

Hi Gerry.

Ok, will do. Latest is abdominal ultrasound was clear and aspirates of liver and spleen also clear.

Re: MCT in a beagle

Gerry Polton — Tue, 07 Apr 2015 08:31:02 GMT

Hi Robin

Can you post the entirety of the microscopic description bit of the path report?

Gerry

Re: MCT in a beagle

John Flynn — Sun, 05 Apr 2015 19:22:56 GMT

[quote user="Robin Grimmer"]the kit test[/quote]

i think this even more waste of resources...

Re: MCT in a beagle

John Flynn — Sun, 05 Apr 2015 19:20:55 GMT

[quote user="Robin Grimmer"]histo came back as grade ll mast cell tumour with good margins.[/quote]

I'm not Gerry, bit I'm sure he'd be able to help most if you post the full histopath report. If nothing else, I'd like to know the mitotic index and how carefully the margins (esp deep) were assessed.

[quote user="Robin Grimmer"]Ki67 test was performed and was 2.51 high.[/quote]

Different labs have very different Ki67 interpretations - I personally think more details are required here, such as lab and methadology and what their validation (if any) has been to clinical outcomes (I'm guessing this is Bridge Pathology if "2.51 high"?). Generallly, I think this test is money down the toilet unless you have a specific pre-test clinical question that it stands a reasonable chance of altering based on the post-test probability...

Re: MCT in a beagle

Robin Grimmer — Sun, 05 Apr 2015 17:24:08 GMT

To be honest, I would have been happy with a grade ll and clear margins and just monitored, but the kit test has caused a bit more uncertainty. Plus because it was assumed to be a wart, excision may not have been as wide as it should have been.

We have consulted an oncologist and they have said either doing nothing or chemo is ok their preference is for vinblastine and pred.

I value people's opinions on here (well most people lol) but was hoping Gerry might chip in ;-)

Re: MCT in a beagle

james herriot lied — Sun, 05 Apr 2015 11:17:52 GMT

It's certainly masivet-able for six months to suppress, but that's eye-wateringly expensive when nothing appears to be happening and I know a lot of oncology bods like their lomustine in these.

In our gentle backwater, we'd be monitoring closely but probably not going for chemo - having the kit mutation demonstrated can be something of a poisoned chalice, as it tends to increase anxiety and I'm not convinced the additional stress is proportionate to risk; funnily enough, I know masivet - informally - no longer demand it prior to using the drug, but they've been told to leave it on the data sheets.

If she's insured, send her off to the oncologist and let them decide.