Plasmacytoma?

RE: Plasmacytoma?

emma o'connor — Tue, 21 Nov 2017 09:55:52 GMT

I have a client with a 9 year old atopic labrador who developed a plasmacytoma on the distal limb, 18 months after starting on apoquel. We stopped apoquel and the owners elected for surgery on the mass, it was horrid and infiltrated all around the tendons of the dorsal foot, we couldn't remove all tissue. They then asked to see a referral oncologist who did further surgery. Sadly the foot never healed well at all and the tumour came back. I am now incredibly careful about starting dogs on apoquel, I obviously do not know if the severity of this tumour was due to the drug or not but I have my suspicions, and did report it as a possible adverse reaction. If the mass is easily resectable I would say remove it ASAP and histo, and stop the apoquel.

RE: Plasmacytoma?

Anthony Dennison — Tue, 21 Nov 2017 09:49:31 GMT

[quote user="Lou Dawson"]Re Apoquel...has it been proven that there’s a link between treatment and nasty skin tumours? wondering what people’s experience is...[/quote]

I only thought that due to the data sheet warnings to be honest

RE: Plasmacytoma?

Lou Dawson — Mon, 20 Nov 2017 21:22:01 GMT

Argh sorry just re-read your initial post and realised you already think its plasmacytoma. Sorry about that. cutaneous lymphomas can be hard to definitively diagnose even with histo when very atypical but it’s low on my list for this case (again, based solely on this image). Re Apoquel...has it been proven that there’s a link between treatment and nasty skin tumours? wondering what people’s experience is...

RE: Plasmacytoma?

Lou Dawson — Mon, 20 Nov 2017 21:04:07 GMT

Hi Anthony

with the caveat that I’m not a cytologist and based only this one image, plasmacytoma would be high on my list. Quite often see this degree of anisocytosis/anisokaryosis, there’s a binucleate cell and an atypical mitosis which would fit. Can kind of see faint perinuclear halos in some cells with a bit of imagination. Russell bodies often not a prominent feature in these more atypical ones. Histiocytomas tend to have a much more uniform appearance on cyto in my (limited) experience. Agree to do stains to exclude MCT. Where on the dog is the mass? Plasmacytomas often lips and feet. hope that helps a little (would always advise sending off if any doubt whatsoever!)

RE: Plasmacytoma?

Beats — Mon, 20 Nov 2017 19:40:39 GMT

Looks most likely histiocytoma to me (but I always drop a drop of toluidine blue on these if in doubt to make sure not MCT with failure of granules to stain with speedy-diff...)

I'd be expecting a clear peri-nuclear halo of golgi in plasmacytoma which I don't personally see.

Weird cutaneous lymphoma unlikely to have that degree of variation in cell size I'd reckon.

What does the lump look like? Clinical particulars likely to affect cytological judgement :-)