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In the February open access episode of Chattering With International Cat Care, Yaiza Gómez-Mejías is joined by Sandra Guillén to discuss her latest JFMS article entitled ’Cutaneous paraneoplastic syndromes in cats: a comparative clinical review.’
Together, they explore how certain feline skin presentations can act as early warning signs of internal disease, discussing key clinical patterns, diagnostic reasoning, and why these cases are so easy to miss. The conversation highlights practical take-home messages for recognising when a dermatological problem may be signalling something far more serious beneath the surface.
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Host:
Yaiza Gómez-Mejías, LdaVet MANZCVS (Medicine of Cats), RCVS CertAP (Feline Medicine), iCatCare Veterinary Community Co-ordinator
Speaker:
Sandra (Alexandra) Guillén, DVM DipECVIM-CA (Oncology) PGCert (VetEd) FHEA MRCVS, Senior Lecturer in Veterinary Oncology
Creators and Guests
Host
Yaiza Gomez-Mejias
Veterinary Community Co-ordinator @ International Cat Care
What is Chattering with iCatCare?
Welcome to Chattering With iCatCare, the official monthly podcast of International Cat Care, hosted by Yaiza Gomez-Mejias (Veterinary Community Co-ordinator). Each month, we chatter about cats and cat-friendly practices with industry experts and contributors to The Journal of Feline Medicine and Surgery. Each episode contains highlights from our longer discussions and interviews, which are accessible to iCatCare members at portal.icatcare.org. If you would like access to our full episodes, would like to become an iCatCare Veterinary Society Member, or find out more about our Cat-Friendly schemes, visit icatcare.org.
Yaiza Gomez Mejias: [00:00:00] Welcome back to Chattering with iCatCare. Today we're tackling a diagnostic challenge that often hides in plain sight, cutaneous paraneoplastic syndromes in cats. While these cases are rare, we will see how the skin can act as an early indicator of occult internal neoplasia, offering an opportunity for diagnosis before other systemic signs emerge. Joining us today is the lead author of a comprehensive new review, published in the Journal of Feline Medicine and Surgery
Sandra is the first author of this month's JFMS Spotlight titled cutaneous paraneoplastic syndromes in cats, a comparative clinical review. So thank you for finding the time to record this episode, Sandra.
Sandra Guillen: No, thank you for inviting me Yaiza.
Yaiza Gomez Mejias: Cutaneous paraneoplastic syndrome seem more common in middle age to older cats, [00:01:00] but putting age aside, what kinds of clinical signs or bits of history should make us think this could be paraneoplastic rather than just another skin disease?
Sandra Guillen: Yeah. Besides age, there are some clinical red flags that we can identify from clinical history, lesion progression, and response to therapy that can also make us suspect of a cutaneous paraneoplastic syndrome. Would say the first one is the fact that neoplastic lesions often have atypical patterns compared to allergic, infectious, or immune-mediated skin disease.
So we typically see an acute onset of quite severe and widespread skin lesions in a cat that was otherwise previously healthy. These lesions tend to have a rapid progression in a lot of cases and they don't typically regress with appropriate medical therapy and sometimes we also see an unusual distribution compared to other dermatopathies.
A [00:02:00] second red flag would be a poor or paradoxical response to the standard treatment. There is minimal or no response to antibiotics or antifungals or corticosteroid treatment, or sometimes there's a trench in improvement, but there is then a relapse that happens quite quickly. A third red flag that is quite common is that we see concurrent systemic clinical signs together with the skin disease.
A lot of these types, they suffer from weight loss or lethargy, anorexia, particularly those cats that have abdominal tumors. They may also suffer from vomiting or diarrhea or PPD, and those that have intrathoracic tumors like thymomas may suffer from respiratory signs concurrently as well. And I would say the fourth red flag would be clinical pathological findings or abnormalities that are not explained by the skin disease.
Only sometimes [00:03:00] we see that these cats, apart from having skin lesions, they also have abnormalities on hematology, like non-regenerative anemias or persistent inflammatory leukogram that we cannot explain with the skin lesions or hyperproteinemia, elevated liver enzymes, these sort of abnormalities. To summarize, if we have a cat with atypical skin lesions that are progressing very fast, that are not responding to treatment or that is concurrently, systemically ill, or having abnormalities on blood tests, I think we should start investigating that and start suspecting that there could be something else.
Yaiza Gomez Mejias: Thank you so much for sharing these very helpful tips. The article mentions that paraneoplastic alopecia and thymoma associated exfoliative dermatitis are the most commonly reported syndromes. Clinically, how these two look different and how can we tell them apart from the feline skin conditions that we see every day?
Sandra Guillen: Yeah, so exfoliative dermatitis [00:04:00] is an immune-mediated cutaneous paraneoplastic syndrome, so typically affected cats they have these generalized scaling erythema alopecia, and normally these lesions, they progress through hyperkeratosis, erosions and crusting. While paraneoplastic alopecia generally presents more with symmetrical alopecia where the skin appears quite shiny but not fragile.
They also differ on how the lesions are distributed, so cat with exfoliative dermatitis generally have lesions over the head, neck and trunk. While cats with paraneoplastic alopecia generally have alopecia on the ventral abdomen, also the neck in some cases, but mainly the medial aspect of the thoracic and pelvic limbs in perineal regions.
So generally to diagnose exfoliative dermatitis, we have to consider as well other possible differential diagnosis such as [00:05:00] mastocytosis, ectoparasitic or allergic diseases, as well as immune mediated skin diseases such as pemphigus or sebaceous adenitis, or drug related reactions, or even epitheliotropic lymphoma can mimic these sort of lesions, so we need to exclude those differentials as well. For paraneoplastic alopecia, the main differentials would be self induced alopecia due to pruritic or psychogenic disorders. Also, dermatophytosis, or demodicosis, or iatrogenic hypercortisolism, among others. So generally the clinical progression of the lesions, the clinical signs of the cat can help us narrowing that differential list and then we can obviously, depending on our clinical suspicion, do this is specific testing to exclude the other possible dermatosis.
Yaiza Gomez Mejias: So you started talking a little bit about the differentials you considered in your workup when a cutaneous paraneoplastic syndrome is on your differential [00:06:00] list. How do you usually complete this workup?
Sandra Guillen: The initial diagnostic test should normally include a complete hematology, biochemistry profile. If we don't know if the cat is the FeLV or FIP positive, we should probably test for that as well and depending on the type of lesions and the progression, we may continue as well fine testing or investigation for ectoparasites, dermatophytes and microbial overgrowth. To obtain a diagnosis ultimately we need a combination of tests that include skin biopsies and imaging to be able to localize basically the primary tumor and rule out other differential diagnosis for those cats. Once we have located the tumor either inside the thorax or the abdomen, we generally have to confirm what tumor type we're dealing with either using cytology or histopathology.
This will help us characterize the type of tumor, but also [00:07:00] the extent of it. For example, if you have a cat with a pancreatic mass and concurrent nodules in the liver, and we want to assess if those two are related. We are gonna consider something of both the primary mass, but also the liver nodules to assess for metastatic disease.
Having said that, if you have, for example, a cat where you document a mediastinal mass and the cat concurrently has exfoliative dermatitis or lesions compatible with it, such as scaling, erythema, or erosions, or crusting all over the body, you can have a very high degree of suspicion just based on the clinical presentation imaging findings.
Yaiza Gomez Mejias: I see. So once we've made the diagnosis, how does that information help us guide owners especially when it comes to prognosis?
Sandra Guillen: Yeah, so the tumor type is gonna give us a lot of information about the prognosis. For example, in cats that have thymoma and [00:08:00] associated exfoliative dermatitis, we know that after surgery these cats can have a good outcome with survivals over two and a half years.
And we have reports as well of cats that have hepatocellular carcinoma and paraneoplastic alopecia, and that can achieve also long-term outcomes after excision of this liver tumor. However, then we have other tumor types like biliary and pancreatic carcinomas in cats that are sometimes associated with this paraneoplastic alopecia.
We see that these cancers, they have an aggressive behavior, and a lot of times we do have metastasis already at diagnosis. So generally the prognosis for those cats tends to be guarded to poor. Despite this, it's worth highlighting that there's a proportion of cats with pancreatic and biliary cancer, that they may have an early disease stage or just localized disease without metastasis, and those cats with appropriate surgery can do better [00:09:00] than previously expected.
When there are other types of cancers, for example, there are some reports of cats with lymphoma and associated paraneoplastic cutaneous necrosis. In paraneoplastic skin fragility syndrome, where we know that potentially chemotherapy could effectively treat the underlying lymphoma and lead to a fair outcome in those cases where we see a good response, so yeah, it depends which cancer we are treating, we are dealing with, and what the treatment options are for that particular cat.
Yaiza Gomez Mejias: That makes sense. Yeah. So while we are still investigating or planning treatment, are there things we can do earlier on to give the cat some relief?
Sandra Guillen: Yeah. It's a really good question. We do see that some of these cats with cutaneous neoplastic syndromes, they often have secondary bacterial or yeast infections, and this is because they have this impaired skin barrier function. So while working on this review paper, we also looked at [00:10:00] the responses that were seen in these cats that were treated with medical management alone without tumor removal or any anti-cancer drugs.
And those types that were treated supportively with antifungal or antibiotic treatment generally had some improvement, but it was very short lasted. So similarly with other cutaneous neoplastic syndromes that we know that are immune mediated, some of these cats may benefit from steroids, but the reports suggest again that some cats may not respond to steroids alone or that these improvement may just be very mild and short. Given that information is somehow limited for some of these cutaneous paraneoplastic syndromes, I think in the palliative setting, I would still recommend symptomatic treatment as it may provide some temporal relief or some of these cats.
Yaiza Gomez Mejias: If we are able to completely remove a non-invasive [00:11:00] thymic epithelial tumor, how likely is it that the skin signs will actually resolve?
Sandra Guillen: That's a really good question as well, because in the majority of cats undergoing excision of thymomas, the exfoliative dermatitis actually resolved. But what we could see in our literature review is that in some of these cats, the resolution is not immediate. It can take one to six months. So we need to give them time after surgery and follow up on them and on the skin lesions.
Yaiza Gomez Mejias: So moving now onto some of the rarer syndromes mentioned in the article, what clinical signs or lab findings should ring alarm bells for something like superficial necrolytic dermatitis?
Sandra Guillen: When looking at superficial necrolytic dermatitis in cats is actually quite a rare syndrome. We could only find four cases in the literature with this sort of paraneoplastic syndrome.
One of these cats had a glucagonoma and another one had an hepatic neuroendocrine [00:12:00] carcinoma and then the two others had hepatic or pancreatic carcinomas. And in all these four cases, the lesions were mainly characterized by the presence of severe erythema, thick cross ulcers and erosions, and some of these cats have also keratosis and deep fissures of the skin, which were generally quite painful or even associated with self trauma.
So the most common areas affected in these cats generally were the ventral paws and other areas of friction and trauma suggest the muscle, the periocular region, perianal regions, and the genital regions as well. What is interesting of this syndrome is that most of these cats, they had concurrent systemic clinical signs and they were unwell. Either they presented with lethargy, anorexia, vomiting, or weight loss and what is also even more interesting is that polyuria and [00:13:00] polydipsia, which is actually one of the main presenting clinical signs in dogs and people because of concurrent diabetes mellitus and insulin resistance is something that was not reported in any of these cats.
And then we have also some other abnormalities, particularly in the biochemistry panel where we can see elevation of liver enzymes, hyperglycemia, again because of these insulin resistance. But this, again, was only reported in two of the four cats, and the other two basically had pretty unremarkable biochemistry.
So again, it seems like some of these clinical signs or lines are a bit more subtle in cats compared to other species. We know that there is a validated glucagon analysis test that can be used in cats. So it's something that, again, for future cases we can consider. But in those reports, none of them actually made the diagnosis based on these, this tests. Instead, the expression of glucagon was made on [00:14:00] basic imunohistochemistry.
Yaiza Gomez Mejias: Oh, interesting. I'm looking forward to seeing what happens in the future, what's discovered. So today's discussion really highlights how important it is for all of us in general practice to look beyond the skin and consider what might be happening systemically in our feline patients. Recognizing these patterns can make a real difference. Thank you so much, Sandra, for sharing your expertise.
That brings us to the end of a fascinating episode, a huge thank you to our guest for guiding us through this complex clinical spotlight.
For those listening, you can find the full review and the summary tables of reported cases in the Journal of Feline Medicine and Surgery. Until next time, keep a closer eye on those atypical presentations. The skin might be trying to tell you a much bigger story.