Is this a dentigerous cyst?

RE: Is this a dentigerous cyst?

Evelyn Barbour-Hill — Thu, 09 Jan 2020 13:44:33 GMT

Thanks for the information Lucy.

You couldn't post a photograph, could you? And maybe some surgical details, like where the bone sections were made?

RE: Is this a dentigerous cyst?

Lucy Fleming — Wed, 08 Jan 2020 12:42:22 GMT

Apologies for the delayed update folks, but I thought I would wait until I had the full story to fill in those interested. Histopathology report from the biopsy we took initially showed some form of odontogenic tumour, suspected of being an infiltrative inductive ameloblastic fibroma.

His owners elected to pursue surgery, and a CT scan and rostral maxillectomy was performed. There was no evidence of distant metastasis, though there was a concern at the time of surgery that the mass extended more caudally than expected. (I should clarify this is from his referral case report, maxillectomies are definitely not in my skill set!)

Histological diagnosis: feline inductive odontogenic tumour. Despite the concerns of the surgeons, the mass does appear to have been completely removed, albeit with a narrow margin dorsally, so we'll continue to monitor the site.

Boris's recovery has been unremarkable, apart from his brother not initially recognising him when he returned from his hospital stay, but apparently they are friends again now ;-)

RE: Is this a dentigerous cyst?

Lucy Fleming — Wed, 27 Nov 2019 20:38:51 GMT

Sorry, I've been meaning to update! I'll get the proper histo report tomorrow when back in work, but yes, an odontogenic tumour of some sort (pathologist couldn't say exactly what from the sample)

RE: Is this a dentigerous cyst?

Evelyn Barbour-Hill — Wed, 27 Nov 2019 18:02:31 GMT

What was the outcome, Lucy Fleming?

RE: Is this a dentigerous cyst?

Lucy Fleming — Wed, 06 Nov 2019 15:58:15 GMT

Thanks all. I've selected Evelyn's answer just to keep all the posts in order, but all equally helpful. Thanks Rob for the pictures - that's pretty much what I was hoping it would look like, but then it didn't.

[quote user="Alexander Geddes"]Was there a missing tooth noted previous in the cats history? Thats likely to give you the answer. [/quote]We've never noted a missing tooth, but that's not to say that it was definitely present - I'm not sure I would always spot a missing incisor on a cat in a general physical examination, and I usually spend quite a bit of time waxing lyrical about teeth.

[quote user="Alexander Geddes"]but when you have teeth involved that are generally in place, avoid removing them; this will potentially increase your definitive surgical margin. Equally try and avoid raising flaps to access tissue for biopsy. I usually recommend an appropriately sized punch biopsy central to the lesion. This will again avoid extending your dirty margins when moving forward with definitive surgery.[/quote]

That's good to know, thanks. I must admit the main reason to raise the flap was to go hunting for that buried incisor I was concerned might be the cause of all the problems; usually I would just biopsy as you describe if that's the plan from the start. The rest of the incisors were pretty loose.

Hopefully I'll be able to update shortly with the histopathology report.

RE: Is this a dentigerous cyst?

Rachel Perry — Wed, 06 Nov 2019 15:10:22 GMT

_{Radiologically, cysts tend to have very well defined borders, with a clear distinction between the lucent area and normal bone, which this doesn't really have. Considering neoplasia, malignancies tend to leave teeth 'in situ' due to their rapid growth, so teeth can look like they're floating in space with no bone supporting them. In contrast, slow growing benign tumours have time to move teeth in an orthodontic way. So, like Alex, I'd have to put money on a benign tumour. Given the age I'd also go for an odontogenic tumour. Surgery is going to involve pretty radical resection though, even if it is a marginal excision. 3D imaging would be very important.}

RE: Is this a dentigerous cyst?

Alexander Geddes — Wed, 06 Nov 2019 13:02:45 GMT

Hey Lucy, great work on getting this cat in for biopsy and thanks for the lovely radiograph!

I agree this could be a dentigerous cyst. But with this level of displacement its not possible to determine now. Was there a missing tooth noted previous in the cats history? Thats likely to give you the answer.

Based on the radiograph and the signalment my money is on a tumour of odontogenic origin - probably an APOT (amyloid-producing odontogenic tumour). Having said that there is heterogenous bony change here and its a cat so SCC should be on the list regardless of age.

Some things to consider when performing these biopsies; in this case the teeth are so displaced removing them concurrently is of little to no consequence, but when you have teeth involved that are generally in place, avoid removing them; this will potentially increase your definitive surgical margin. Equally try and avoid raising flaps to access tissue for biopsy. I usually recommend an appropriately sized punch biopsy central to the lesion. This will again avoid extending your dirty margins when moving forward with definitive surgery.

Hope that helps and keep us in the loop!

RE: Is this a dentigerous cyst?

Rob Davis — Wed, 06 Nov 2019 12:37:30 GMT

[quote user="Lucy Fleming"]We raised a flap, extracted all the incisors, and biopsied the spongy tissue they were embedded in. I wasn't brave enough to attempt to curette out all the tissue as there wasn't really a clear distinction with healthy tissue to tell me when to stop! [/quote]

This doesn't sound much like a dentigerous cyst to me. Usually they are full of fluid which drains out as soon as you incise, leaving a clearly visible lining like this:

[quote user="Lucy Fleming"]Is this consistent with a dentigerous cyst, or should I be sending the biopsied tissue to the lab to look for something else?[/quote]

Definitely send for histopathology and please update us with the diagnosis!

RE: Is this a dentigerous cyst?

Evelyn Barbour-Hill — Wed, 06 Nov 2019 12:15:08 GMT

Well, it could be, or maybe not.

[:D]

It looks very destructive in a moth-eaten sort of way on this picture. A d. cyst usually looks expansile.

And the surgical appearance: usually obviously cyst-like.

Definitely send the tissue for histopathology.