Ocular Oncology and Pathology
This section covers ocular oncology and pathology: intraocular tumours, surface tumours, lymphoproliferative disease, and diagnostic principles. The exam tests recognition, staging, and when biopsy is contraindicated.
Core rules and concepts
- Retinoblastoma presents with leukocoria or strabismus; RB1 mutation is the key genetic event, and calcification on CT supports the diagnosis.
- Uveal melanoma is the commonest adult intraocular malignancy; BAP1 loss is associated with metastatic risk. Treatment includes plaque brachytherapy, proton beam, or enucleation.
- Conjunctival melanoma arises from primary acquired melanosis or naevus; wide local excision with cryotherapy or topical chemotherapy is used.
- Primary vitreoretinal lymphoma masquerades as uveitis; vitreous biopsy with cytology and gene rearrangement confirms it.
- Pathology uses H&E, immunohistochemistry, and molecular markers; margin status and tumour thickness guide prognosis.
Worked example
A 2-year-old has a white pupillary reflex. Ultrasound and CT show an intraocular mass with calcification. The diagnosis is retinoblastoma. Biopsy is contraindicated because it risks extraocular spread. The child is referred to a specialist centre for staging and treatment, which may include systemic chemotherapy, intra-arterial chemotherapy, focal therapy, or enucleation. Genetic counselling is arranged because germline RB1 mutation increases the risk of bilateral disease and second malignancies.
Traps that cost marks
Do not biopsy a suspected retinoblastoma. Leukocoria is not always cataract; check the red reflex and imaging. Missing BAP1 risk in uveal melanoma limits surveillance. In elderly patients with chronic uveitis, consider lymphoma. Always document tumour margins and send suspicious conjunctival lesions for histology.