Microscopy May 2018

Quiet session this month, possibly because of it being busy with the recent ARVO meeting, the ECVO meeting, and the upcoming RCOphth Congress. Still,
we chatted about a fair range of eye pathology topics yesterday, from rare corneal dystrophies to ocular trauma to the value of deeper sections. Here are a few of the cases we reviewed.

Case 1

Orbital biopsy, very posterior lesion and difficult to access.

This biopsy came as several piece of fatty tissue.

Orbital biopsy

Initial H&E sections didn’t show very much.

Orbital biopsy – higher power

However, on cutting deeper levels, a small cluster of tumour cells became visible.

Orbital biopsy – high power

They are cytologically bland, have oval nuclei with inclusions, modest cytoplasm and syncytial borders.

Immunohistochemistry was positive for EMA and vimentin, and negative for AE1/AE3 (a pan-cytokeratin), S100 (neural), SMA (smooth muscle) and MelanA (melanocytic).

The appearance is consistent with a meningioma.


Case 2

Cornea from a patient with keratitis, suspected to be fungal.

Cornea

The H&E view shows an unhealthy cornea lacking epithelium and with a scattering of inflammatory cells and nuclear debris within the stroma: consistent with keratitis.

Posterior cornea – high power

Descemet’s membrane is fragmented although this may well be due to the specimen being divided after surgery so that some could be sent for microbiology investigation.

Cornea – Grocott stain

Grocott stain showed a couple of vaguely discernable shapes just anterior to Descemet’s membrane but I didn’t feel able to confirm that these were fungal elements with a high level of confidence.

Cornea – repeat Grocott

However, a repeat Grocott shows hyphae and spores much more clearly (and more of them).

This is fungal keratitis.

Cases 1 and 2 underscore that histological evaluation is a sampling exercise and that pathology may not be present in all sections.


Case 3

Material removed from lacrimal sac at DCR surgery.

Lacrimal sac biopsy – low power

These are pieces of fibroconnective tissue consistent with lacrimal sac wall. There is a diffuse inflammatory infiltrate and patchy scarring consistent with chronic dacryocystitis.

Lacrimal sac wall – medium power

However, the striking feature is of scattered brown pigment granules throughout the entire specimen. There are also rounded optically empty spaces that I would normally associate with lipid: not a usual finding in lacrimal sac.

Lacrimal sac wall – high power

On higher power, the inflammatory infiltrate includes lymphocytes and macrophages, and possibly a couple of multinucleate giant cells.

Perls’ stain (for iron) and Masson Fontana (for melanin) were both negative.

Given the presumed exogenous pigment and possible oil, and the location in the lacrimal sac, I suggested this was a reaction to cosmetics, ie a “mascaroma”.

Shields, J. A., Marr, B. P., Shields, C. L. & Eagle, R. C. Conjunctival mascaroma masquerading as melanoma. Cornea 24, 496–497 (2005).

Ciolino, J. B., Mills, D. M. & Meyer, D. R. Ocular manifestations of long-term mascara use. Ophthal Plast Reconstr Surg 25, 339–341 (2009).

Pao, K. Y., Murchison, A. P. & Eagle, R. C. Unilateral non-pigmented palpebral conjunctival lesions due to cosmetics use. Ophthal Plast Reconstr Surg 28, e107-108 (2012).


Case 4

Corneal opacity in a middle aged patient who has already had surgery on the other eye.

DALK specimen

This is a DALK specimen (anterior corneal lamella). It isn’t always easy to differentiate surgical changes from pathology.

DALK specimen – higher power

On higher power, the anterior part of the stroma has an odd texture. The collagen has a fibrillary or feathery appearance. For comparison, this isn’t a completely normal cornea but the anterior stroma is of more typical compactness.

DALK specimen – high power

On higher power still, there are scattered tiny rounded spaces which as with Case 3 suggest lipid.

This is Schnyder’s dystrophy.

Arnold-Wörner, N., Goldblum, D., Miserez, A. R., Flammer, J. & Meyer, P. Clinical and pathological features of a non-crystalline form of Schnyder corneal dystrophy. Graefes Arch. Clin. Exp. Ophthalmol. 250, 1241–1243 (2012).

Nowinska, A. K. et al. Phenotype-genotype correlation in patients with Schnyder corneal dystrophy. Cornea 33, 497–503 (2014).

My next microscopy session will be on June 13th. See you then!

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