Pug with Mast cell tumours and thrombocytopaenia

Re: Pug with Mast cell tumours and thrombocytopaenia

Tim Charlesworth — Tue, 10 Dec 2013 11:40:06 GMT

I saw a labrador recently with a high grade MCT next to its nasal planum but which had metastatic MC's on splenic and hepatic aspirates so did not go to surgery. I just found out yesterday (from the referring vet ) that the dog was recently PTS for going into full blown Evan's syndrome (IMHA + thrombocytopenia) shortly after starting Masivet - I'll prompt them to report it as a possible adverse effect.

Kara - is there any way you could upload a photo of the MCT in the foot? - In previous cases we have "shrunk" the MCT with preoperative prednisolone and then resected interdigital MCTs together with the 2 neighbouring toes (ie IV + V, II + III or III + IV) and the dogs have gone on to do very well (one was even a working dog who contnued to work). Happy to have a look if you have any piccies - you can email me through the practice link if you can't upload them here,

Best of luck with the case,

Tim

Re: Pug with Mast cell tumours and thrombocytopaenia

Gerry Polton — Mon, 09 Dec 2013 08:20:44 GMT

Hi Kara

I empathise with you. These are real problem cases. Is she still receiving the same dose of prednisolone?

I have not come across masitinib induced thrombocytopenia. If you have not done so already, this is something that should be reported for pharmacovigilance purposes. Is it conceivable that the thrombocytopenia arose due to some other mechanism (I realise that saying this might simply make me look daft without the advantage of the whole record in front of me)? Daftness aside though, the point is worth making because you are struggling to find a management strategy at the moment while the assumption of drug-induced thrombocytopenia remains.

If you do not wish to risk use of masitinib again, you can of course consider toceranib (Palladia). If there was an immune-mediated thrombocytopenia triggered by the masitinib, it is not necessarily reasonable to assume that a different molecule would induce the same effect. I would advise concurrent prednisolone administration, not least because this is an angry-sounding tumour which will have a higher chance of degranulation effects and other side effects.

Radiation therapy is an appropriate treatment strategy for distal limb mast cell neoplasia without evidence of lymph node or distant metastasis. Degranulation is a risk and we therefore manage these cases with concurrent corticosteroids to mitigate against this.

As previously stated, vinblastine and prednisolone offer a useful alternative. There was a time before masitinib when this combination seemed quite a good idea. It can't be completely useless now.

I would be happy to take a look through the notes if there is room to doubt the causality fo the thrombocytopenia.

Best of luck

Gerry

Re: Pug with Mast cell tumours and thrombocytopaenia

David Mills — Sat, 07 Dec 2013 01:47:02 GMT

Amputate.

Even with TKIs, surgery remains the treatment of choice for cure. This tumour will highly lead to PTS much sooner on medical treatment - whether 1ry tumour or 2y ulceration - and it sounds like the dog is painful at the moment. The longer it is left, the more chance of spreading. I think masivet is the likley culprit for the myelo problems so what options are there, realistically, for maintaining a long(ish) and quality life? I agree that vinblastine runs a similar risk.

It's also a pug so not running marathons or herding sheep so it'll do fine on 3 legs. It's a quick, straightforward operation, and will likely cost much less than continued medical treatment and monitoring and with a greater QoL.

Why is the owner resisting surgery? Age? (Not that old) Or some perceptual problem? Sounds like they need convincing. As a halfway house, sample the popilteal and inguinal LNs (if can find the latter) to ensure no spread.