Biopsies in feline lymphoma

RE: Biopsies in feline lymphoma

Martin Atkinson — Tue, 22 Nov 2016 11:49:35 GMT

[quote user="Stephanie Fursland"] I am concerned will increase her risk for GIT wound breakdown after biopsies [/quote]Its never been an issue for me, I would think that dose rate would not delay healing. I have usually started chemotherapy within a couple of days, as soon as diagnosis is confirmed, without issues but as Gerry said its a balance between getting some therapy going if you're really concerned or waiting for the steroid effect to wane. As ever you need to explain the risks and benefits of each option with the client. Perceived wisdom used to be to stage the induction of chemotherapy with intestinal lymphoma so as not to risk intestinal perforation regardless of biopsy wounds anyway but I'm not sure how much that holds true today.

Incidentally, I'm treating a cat with intestinal lymphoma with just immunosuppressive doses preds and cyclophosphamide as the owner didn't want to go down the full COP route and its been in remission for over a year now so its definitely worth a go.

RE: Biopsies in feline lymphoma

Stephanie Wellings — Tue, 22 Nov 2016 11:33:13 GMT

Thankyou! That is very helpful :-)

I have actually just inherited this case, and ended up having long conversations with the owners without ever actually having examined it...but my understanding is that the steroids have not made a huge difference to the symptoms, and when it was scanned five days ago there was 'diffuse intestinal thickening, mainly in the mucosa, and significant enlargement of mesenteric lymph nodes'.

I think this cat is having fairly significant weight loss and deteriorating quickly, so I would ideally like to biopsy as soon as is safe to do so - the steroid dose she is on is 0.7mg/kg BID, which I am concerned will increase her risk for GIT wound breakdown after biopsies - or is the fact we are cutting into an already compromised gut the main risk in this situation?

Thanks again!

RE: Biopsies in feline lymphoma

Gerry Polton — Tue, 22 Nov 2016 09:36:21 GMT

As a rule, lymphoma can still be diagnosed histologically even in the face of concomitant steroid administration. I know that's not what everyone tells you. It's not all a grand conspiracy to shake your confidence. There are some instances when it does make a difference, but they are circumstances when the yield of diagnostic material would be low. For example, in cytology, if fine needle aspirate technique is poor already, corticosteroid administration is going to reduce viability of cells leaving you fewer cells of diagnostic quality. Similarly, if you obtain small core biopsies of a lesion, and there was already plenty of necrosis, for example if trying to diagnose a cranial mediastinal mass by transthoracic core biopsy, the addition of steroids will diminish the proportion of cells surviving and the likelihood of diagnosis would fall. So, you can kind of imagine a graphical representation of the likelihood of diagnosis and as your likelihood gets lower, so the impact of steroids gets greater.

By contrast, if you have chunky abnormal tissues, and if your biopsies are generously proportioned and delicately obtained, the degree of steroid induced necrosis will not interfere with diagnosis. So, echoing Martin's point, if there has been no real change in the apparent proportions of the abnormal tissue, and if you are prepared to take multiple decent sized biopsies, you have a good chance of making a diagnosis. If, instead, the bowel thickening were to be no longer palpable, you might need to prepare yourself for the ignominy of reporting a non-diagnostic result.

Please also be aware that immunohistochemistry results can be adversely affected by prior corticosteroid administration.

Then to the question of how long the steroids should be withdrawn: well, many of you will be thinking, hang on, without steroids for four weeks, the patient in my imagination would die or be euthanised. This is an important consideration. So, steroids should only be withdrawn if you believe that doing so will be tolerable. Assuming that the disease process is sufficiently indolent that you can withdraw steroids for four to six weeks, that would be the interval I would recommend.

I hope that makes sense

Gerry

RE: Biopsies in feline lymphoma

Martin Atkinson — Tue, 22 Nov 2016 08:56:42 GMT

I think we need to wait for Gerry on this one for the definitive answer. But I would answer first with a question: has there been any significant reduction in size of the lymph nodes or thickening of the gut? If not, I think your biopsies will be representative. As for pre-emptive steroids affecting future chemotherapy the logic is that chemo works by hitting rapidly dividing cells and if you've suppressed the little b*ggers then they may not be as responsive. I'm not sure how critical this is but probably not as bad as is often made out in the short term at least.