Yesterday we had our second eye pathology microscopy session using the new system funded by Friends of Moorfields and the camera functionality came in really useful for comparing images between different slides. We focussed on orbital pathology, with lesions of the lacrimal sac, lacrimal gland and orbital soft tissue.
The highlight of the session was the hippopotamus eye brought along by Simon, which led to some interesting comparative discussions!
Here are some of the cases we discussed.
Case 1 – lacrimal sac mass in a middle aged patient
The low power view shows fibroconnective tissue with nests of tumour cells, some of which have central necrosis. There is associated inflammation.
At higher power, keratinisation can be seen in the centre of some of the tumour nests. This is squamous cell carcinoma.
Case 2 – lacrimal gland mass
The low power view shows a tumour (lower field) with a rim of atrophic and inflamed lacrimal gland (upper field). The tumour cells are spindled with clear or pale cytoplasm. There is somewhat myxoid stroma with fibrous areas. The appearance suggests a rather cellular pleomorphic adenoma.
However, on higher power, there are worrying nests intermingled with the background tumour. The nuclei are more pleomorphic, with scattered mitoses and prominent nucleoli. The final diagnosis is carcinoma ex pleomorphic adenoma. As the malignant tumour is confined to the centre of the specimen, the prognosis is stated to be the same as a completely benign pleomorphic adenoma.
Case 3 – rapidly growing orbital mass
A low power view shows a very “busy” field, with fibroconnective tissue and inflammation. There are several large granulomata of varying size and shape, with an intervening infilrate of lymphocytes, plasma cells and eosinophils. The granulomata show central necrosis.
The higher power view shows a large Langhans-type multinucleate giant cell.
The differential diagnosis is wide, but includes infections such as tuberculosis as well as systemic disease such as sarcoidosis. In this case, Ziehl–Neelsen stain was negative, but this does not exclude the possibility of tuberculosis.
Case 4 – hippo ocular histology!
This specimen was rather outside our realm of experience, but we thought the eye was likely to be normal for the age and species. There were some features that contrast with human histology, although as we only had this one case to examine, we can’t be sure it’s representative!
Examination of the angle and ciliary body suggests that the ciliary muscle is relatively meagre compared with that of humans. Additionally, the processes of the pars plicata appear more slender and complex in the hippo. The iris appears attached to Descemet’s membrane, which may be pathological as this could cause angle occlusion.
The hippo retina appears different to that of humans. The photoreceptor inner segments appear almost club-shaped, as opposed to very slender rods and triangular cones of humans. We believe that hippos are predominantly nocturnal, so we might postulate that they have club-shaped rods.
Thanks to everyone who attended for the great discussions we have about these and the other cases! If anyone would like to comment on the cases above, particularly regarding normal hippo anatomy, we’d love to hear from you!
See you next month!