Microscopy May 2019

This month, Simon and Alejandro from the Royal Veterinary College were able to join us. Congratulations to Alejandro on his new appointment!

Alejandro brought along a globe with a diagnosis of equine recurrent uveitis (ERU). As you might expect from the name, there’s a chronic inflammatory infiltrate within the iris and ciliary body. Interestingly, there is also amyloid deposition within the ciliary processes and as a layer on top of the non-pigmented ciliary epithelium.

The horse eye has an interesting (to me) “frilly thing” hanging down from the iris. This is called the corpora nigra (Simon/Alejandro, please correct me if I’m wrong). You can see a clinical example on my writing site here, which features an interview with veterinary ophthalmologist Charlotte.

ERU has an association with Leptospira, and it’s commoner in Appaloosas. If you want to know more, here are a few open access articles:

Sandmeyer (2017) reviews demographics of horses with ERU in Canada.

Malalana (2017) investigates Leptospira in horses with ERU in the UK.

Faber (2000) assesses Leoptospira in the aqueous of horses with recurrent uveitis.

Now for a few human cases!

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Case 1

Evisceration for keratitis, perforation and endophthalmitis.

This case wasn’t a great diagnostic puzzle. On low power, we can see there is haemorrhage (top right) and extensive disorganisation of the intraocular contents. There is also a dense mixed inflammatory infiltrate (on the left). There’s also something else.

On higher power, I’d like to draw your attention to the round greyish structures. These are in the vitreous cavity and represent asteroid hyalosis.

Asteroid hyalosis is usually an incidental finding, although I believe they can rarely become visually significant.

There’s a recent open access article by Burris (2017) exploring whether asteroid hyalosis is more common in patients with uveal melanoma.

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Case 2

This is material removed from the orbit of a patient who had retinal detachment surgery many years ago.

This low power view shows a fibrous capsule with suture material, in keeping with previous surgery plus some kind of implanted material/device.

And this is a low power of the other “stuff” that was removed. It’s acellular and rather homogenous. There were a few chronic inflammatory cells, but it does seem largely inert.

On higher power, there is a texture which appears quite uniform throughout.

My best guess is that the patient had a plomb made of hydrogel or a similar material. Because it was so long ago, I don’t think we’ll ever get an exact history.

I found a review by Kreissig (2016) on techniques in retinal detachment surgery over the years, starting in 1929! She doesn’t go into depth about surgical materials, but it’s an interesting read.

Case 3

Globe of a child.

There are no diagnostic surprises here: it’s a retinoblastoma. On low power, we can see a small round blue cell tumour with large areas of necrosis. It extends into the optic nerve although not to the cut end.

I’ve already posted a couple of photos on Twitter, and I’ll be demonstrating the same case at the Royal College of Ophthalmologists Congress in Glasgow next week.

These are the most beautiful rosettes I’ve ever seen!

My next teaching session will be on 19 June. Nearer the time, I’ll send a sign-up link to Moorfields trainees/fellows and people on my mailing list. See you then!