Teaching August 2018

This month’s session was pretty mix’n’match, starting with an excellent introduction to working in the Moorfields Accident & Emergency service by Dr Gordon Hay. A special welcome to those who have just started working for the Trust! I followed up with an introduction to eye pathology, including some case discussions. We then ended the afternoon with a laboratory visit with some hands-on activities.

Here’s one daring fellow embedding a piece of (uncooked) spaghetti in a mould.

Here, David (our Laboratory Manager) is showing paraffin wax blocks to our visitors, so they can appreciate how the tissue is transformed after they submit their specimens.

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Here are a couple of cases from the introductory lecture.

Case 1 – Globe

We do not routinely take macroscopic images, but this case was quite striking. This is the “main block” from an enucleation specimen, after it has been sliced open and the two calottes (caps) removed. (The calottes can be processed separately). There is a sizeable dark brown tumour within the choroid, with disruption of the sclera and extraocular spread. The crystalline lens has become dislodged, and there is a dark brown ring on its anterior surface from iris pigment deposition, possibly because of posterior synechiae.

 

A low-power view of the same specimen shows cornea, iris, ciliary body and lens on the lower right, with tumour extending through the sclera towards the left. Because the extraocular extension of this melanoma is >5 mm, the tumour will automatically be pT4e in the TNM classification. For a recent article on staging of uveal melanoma, look here.  (The article refers to AJCC staging while in the UK we use UICC staging, but the categories are the same).

 

A higher power view of the iris in this globe shows a sheet-like proliferation of blood vessels across the anterior iris surface (on the right). This is rubeosis, which is a common secondary pathology in intraocular melanoma.

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Case 2 – Orbital biopsy

A low power view shows fibrofatty tissue with a cellular infiltrate with some vaguely rounded structures. Even at this power, multinucleate giant cells are easily visible.

 

A higher power view conforms the presence of granulomas, with a relatively light intervening inflammatory infiltrate.

 

Granulomatous inflammation within the orbit is relatively common. In this case, we also did immunohistochemistry for CD68, which highlights histiocytes (remember, granulomas are composed of epithelioid histiocytes). The CD68 nicely highlights the clusters of histiocytes.

Granulomatous inflammation is usually not difficult to identify. However, we can rarely offer a specific diagnosis. Clinicopathological correlation is essential.

My next projection microscope session will be on 5 September. As usual, a sign-up link will be sent out nearer the time. I hope to see some of you there.