Microscopy July 2019

For yesterday’s session, we welcomed regulars from Moorfields Eye Hospital and the Royal Veterinary College as well as two new attendees. Shivani is visiting us from Perth, Western Australia, and Atul is a neuropathology trainee.

To start with, we had a brief chat about how uveal melanomas are genetically different from conjunctival melanomas. I had recently come across an article by fellow NSOPS pathologist Hardeep Singh Mudhar that investigates genetic profiles of primary orbital melanoma. Intriguingly, his cases seemed to have either uveal-type or conjunctival-type profiles. Here’s the PubMed link to Hardeep’s article (unfortunately it’s not open access). We also chatted about extraocular spread of uveal melanoma and whether it’s frequent. Our own department recently did a review of extrascleral extension (ESE) in uveal melanomas, and you can read about it here. Unfortunately, it’s again behind a paywall.

Here are a couple of the cases we discussed.


Case 1

Orbital biopsy

Low power

On low power, we see nests of rather pale eosinophilic (pink) cells in a fibrous stroma. The nests are found at quite distinctly defined.

 

Medium power
High power

Medium and high power views show ill-defined cell borders, copious eosinophilic cytoplasm and oval nuclei with occasional intranuclear cytoplasmic inclusions.

EMA immunohistochemistry

Immunohistochemistry for EMA (Epithelial Membrane Antigen) is positive.

This is a meningioma.

Atul told us about mengioma subtypes: most are WHO Grade 1, but some are Grade 2 (atypical, clear cell and chordoid) and even Grade 3 (anaplastic, rhabdoid and papillary). We also chatted about the use of radiotherapy and surgery as treatment options.

Here’s an open access article from Lancet Oncology (2016) giving the current guidelines.


Case 2

Globe with endophthalmitis

Low power

No surprises here. This medium power view is of the vitreous cavity (you can see the ciliary body epithelium on the top right) which is filled with granulation tissue and inflammatory cells.

Higher power

This higher power confirms the presence of multinucleate giant cells.

Low power

More centrally in the vitreous cavity, there is a sizeable abscess which is filled with necrotic material and inflammatory cells. There is some disorganised retina in the lower part of the field, and the granulation tissue from the previous image is in the higher part of the field.

PAS stain

PAS stain demonstrates enormous numbers of fungal hyphae.

Grocott stain

The hyphae are also visible with Grocott stain although I don’t think so many are showing up as distinctly positive.

This is fungal endophthalmitis.

We chatted about endogenous and exogenous endophthalmitis, and Liam educated us as to various surgical risks: for example, cataract surgery and glaucoma surgery. We looked at another eye that had been removed following trauma, with extensive suppurative endophthalmitis. And Simon had brought along a cat eye removed for endophthalmitis. The suspicion in Simon’s case was that there had been penetrating trauma with a possible retained foreign body, but it wasn’t possible to find a scleral perforation.

Here are a couple of recent open access reviews about endophthalmitis.

Durand in Clinical Microbiology Reviews (2017)
Sheu in Korean Journal of Ophthalmology (2017)

I’m taking a break from teaching in August, and my next session will be on September 18th. See you then!

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