Ocular Oncology and Pathology
Ocular oncology and pathology links a clinical picture to a histological diagnosis. The exam expects you to know the common intraocular and adnexal tumours, their metastatic risk, and the stains that confirm them.
Core rules
- Retinoblastoma: the most common intraocular malignancy of childhood, often before 3 years. Leucocoria and strabismus; calcification on imaging; genetic testing for RB1. Enucleation for advanced disease, chemoreduction plus focal therapy for globe salvage.
- Uveal melanoma: adults, pigmented choroidal mass, subretinal fluid, orange pigment, acoustic hollowness. Metastasis is haematogenous to the liver; monitor with liver enzymes and imaging. Treatment is plaque brachytherapy, proton beam or enucleation.
- Basal cell carcinoma: the most common adnexal malignancy, pearly edge, ulceration, lower lid. Excision with margin control; avoid radiotherapy in young patients.
- Sebaceous carcinoma: elderly, upper lid, masquerades as blepharoconjunctivitis; pagetoid spread; needs wide excision and map biopsies.
- Orbital lymphoma: older adults, salmon-patch conjunctiva, moulds to orbital structures; biopsy for flow cytometry.
- Pathology: melanoma stains with HMB-45, Melan-A and S100; retinoblastoma shows Flexner–Wintersteiner rosettes; lymphoma is CD20 positive.
Worked example
A 3-year-old has a white pupillary reflex and a 2 mm pale retinal mass with calcification on ultrasound. The diagnosis is retinoblastoma. You examine under anaesthesia, image both orbits and the brain, and obtain genetic testing. Because the tumour is small and peripheral, you offer chemoreduction with focal laser rather than immediate enucleation; if the tumour fills more than half the globe or there is neovascular glaucoma, enucleation is preferred. The reasoning is that globe salvage matters, but survival comes first.
Traps
Biopsying a suspected retinoblastoma through the globe, treating a sebaceous carcinoma as chronic blepharitis, and missing liver metastasis in uveal melanoma.