Hi, my name is Alison Lee and I'm an anatomic pathologist at Nationwide Laboratories. And for the next few minutes, I'll briefly share a case based on some biopsies from a chameleon and some details regarding the clinical condition in question. So we didn't get much information about this animal.

All we were told is he's a male comedian, and we don't know the exact species or the age. And similarly, we weren't told much about the history. All we were told was that he had a mass around the left eye and other similar masses elsewhere.

And this, these images are taken from a paper which I'll discuss later. And hopefully they show similar lesions to the gross, lesions in this case. We see multifocal grey ulcerated nodular lesions within the skin, which were pale when incised.

And here is a sub-gross image of the histologic lesions from the biopsy that we saw, which struck me as interesting as they seem to have two distinct parts. So in area one, which I've highlighted to the left, we can see this exophytic mass which resembles a papilloma, whereas in area 2 we see a more disorganised looking mass which is expanding the dermis. So let's have a closer look.

In area one, we see these epithelial cells which are palisading along the basement membrane and giving rise to keratin towards the centre. And on closer inspection, we see that there's a loss of normal layering. There's also very abundant mitotic figures and some cells undergoing individual caratinization, as well as a moderate degree of an isocytosis and an isokaryosis.

Now let's have a look at area 2. Here we see an infiltrative unencapsulated mass of cords, tubercula and islands of epithelial cells within the dermis which undergo caratinization to form keratin pearls. And closer up, we see that there is very, very marked cellular typia here with a very wide variation in cell and nuclear size and shape.

And we also have some multinucleated cells and we see multifocal keratinization. And if we go closer and again, we can see mitotic figures and some of which look quite bizarre. And again, you can really appreciate the very high degree of cellular atypia.

And in both areas here, we see that there's necrosis and heterophilic inflammation. So the diagnosis we went with, unsurprisingly, was squamous cell carcinoma. Although I did wonder about the possibility of a papilloma maybe as a precursor lesion, given the appearance of area one, which I showed you earlier.

And this condition has been described in the literature. So there is a case series by Mayeretta, which describes a multicentric squamous cell carcinoma in seven male panther comedians. And the gross lesions were similar to the images I showed you earlier, and they were grey, ulcerated with loss of scale definition, and they were non-painful, multifocal and variable in size.

And the lesions mainly occurred on the dorsal and lateral body wall, the eyelid, the tail, and the limbs. And on histology, this paper describes squamous cell carcinoma as the morphologic diagnosis with a moderate degree of cellular atypia, although I would say in my case, the cellular atypia is quite marked. And this paper also mentions papilloma type lesions similar to what I saw.

And in two of the animals here that underwent postmortem, there was metastasis to the lungs. So this study investigated the possible causes of these lesions, and they carried out transmission electron microscopy as well as PCR for various different viruses, but they did find no evidence of viral involvement. They discussed the possibility of UV light as a causative agent, given that the lesions were all located in areas that would have been exposed to the light, and obviously chameleons are supplied with a UV light for basking purposes.

And based on conversation with the owners, it was thought that 3 of these animals were exposed to a higher degree of UV light than they would be in the natural environment. And this paper also mentions the fact that all animals in the study were male, but this may simply reflect the fact that males are most commonly kept as pets, as male comedians have brighter coloration than females rather than an actual sex predisposition. So in terms of treatment then, sur surgical excision appeared effective as a treatment for solitary masses as masses did not recur when completely excised, but new lesions developed in the same animals at other sites.

Emilimud cream was used as a treatment in one animal, but it did cause very marked inflammation in the adjacent skin, and due to this side effect, it was discontinued. And cryotherapy was used in two animals, and it was thought to be partially successful as it seemed to fully resolve some of the lesions. But in other areas, neoplastic tissue remained at the site when examined histologically.

And there's a couple of other case reports detailing this condition in the literature. One describes squamous cell carcinoma in a one year old female comedian in the periorbital area, and the differential diagnosis for this was an abscess as the tumour was secondary infected. So squamous cell carcinoma could be a differential for suspected periorbital abscesses in this species.

And another study describes the use of carboplatin beads implanted at the site of the tumour. Which did seem to cause reduction in size of the lesion, which was too large for surgical excision. So I just wanted to share this case as I don't get to see a lot of reptiles day to day, and it's good to know conditions that may occur in these species that we don't see so often.

And I hope you find this interesting, and I have a few references here if anyone wants to do any further reading. And thank you all very much for listening.