Now that I’m not doing face-to-face teaching sessions, I plan to post educational eye pathology cases online. These are likely to be exam-type cases (for ophthalmology and pathology trainees) and/or common cases that a pathology laboratory might receive for reporting. Those of you following my teaching blog might notice some repeats from previous posts, but I’ll try not to overlap too much. I’ll include photomicrographs with commentary to demonstrate relevant features. I’ll also include links to journal articles for further reading: as far as possible, I’ll try to link to open access articles.
As an experiment, I’m posting plain and annotated images (which you can click on to enlarge). Unfortunately, I don’t think there’s an easy way to hide them on this platform, so if you’re testing yourself, you’ll just have to not peek!
Enucleation from an infant
In the upper half of this image lie fragments of tumour without recognisable anatomical structures. The tumour consists of small round blue cells. There is rosette formation. The appearance is consistent with retinoblastoma.
At the bottom of the image lie the choroid (labelled) and retinal pigment epithelium (RPE, marked with yellow line). There is a cellular proliferation above Bruch’s membrane on the right. Since these proliferating cells don’t resemble tumour cells, I interpret this as being a reactive RPE proliferation. (If you disagree, please feel free to offer an alternative interpretation!) In any event, there is no choroidal infiltration.
This higher power view of the tumour shows both Flexner-Wintersteiner (with a lumen, labelled) and Homer-Wright (without a lumen, labelled) rosettes.
Unusually, the anterior segment of this eye is also involved by tumour. A sizeable sheet of tumour lies in the anterior chamber (space bounded by the cornea anteriorly and iris posteriorly). I’ve outlined it in yellow. Clumps of tumour cells also lie in the posterior chamber (space between the posterior iris and lens) close to the ciliary processes. I’ve outlined it in blue. The scattered heavily pigmented cells are probably melanophages.
This higher power view of the angle shows tumour cells infiltrating the trabecular meshwork (labelled “TM”) and coating the anterior iris surface.
In retinoblastoma, anterior chamber invasion is one of the high-risk histological features (HHRFs) indicating an increased risk of metastasis and death. However, anterior chamber invasion is usually seen in tumours with other HHRFs such as massive choroidal invasion and optic nerve invasion. I’m not sure whether anyone has demonstrated anterior chamber invasion alone to be a risk factor for metastasis.
Further reading (freely accessible)
If you’re unfamiliar with the terminology of eye anatomy (for example, the anterior vs posterior and chamber vs segment issue), here are a few web resources:
Gross Anatomy of the Eye from Neuroanatomy Online, McGovern Medical School
Gross Anatomy of the Eye by Helga Kolb
Eye Anatomy and Function from Michigan Medicine
The pathology of ocular cancer by Ralph Eagle. This article gives an overview of melanoma and retinoblastoma, and includes nice images of the different rosette types as well as fleurettes
A new rosette in retinoblastoma by Das et al. The authors in this article propose a new rosette type as well as reviewing the different rosette types
Histological high-risk features
Retinoblastoma patients with high risk ocular pathological features: who needs adjuvant therapy? by Chantada et al. This is a fairly old paper, but still of interest.
Standard reporting of high-risk histopathology features in retinoblastoma This is a guide I put together with Dr Esin Kotiloglu Karaa for the Community Eye Health Journal
Update on pathology of retinoblastoma by Singh and Kashyap. This is a recent update including prognostic features and biomarkers.
Given that these posts replace my previous face-to-face teaching, I’d love to chat in the comments below. Please note, however, that this is an educational blog, and I do not provide medical advice.