Title: More than a cataract: Choroidal melanoma diagnosed on B-scan ultrasonography following an abnormal pre-operative examination
Abstract:
Background: Choroidal melanoma is the most common primary intraocular malignancy in adults, arising from melanocytes within the uveal tract. It makes up to 90% uveal melanomas, followed by tumours of the ciliary body (7%) and iris (2%) 1-3. The median age at diagnosis is approximately 60–62 years, with incidence rising with age and a recognised peak between the seventh and eighth decades 2, 3. Despite its clinical significance and an increased tendency for metastases, particularly to the liver, choroidal melanoma is typically asymptomatic in its early stages and may be missed on routine slit-lamp examination or indirect ophthalmoscopy, especially when the view of the fundus is limited by media opacity such as cataract, vitreous haemorrhage, or corneal pathology 4,5. A previous study has documented patients who underwent uncomplicated cataract surgery, including intraocular lens implantation, in eyes later found to harbour a previously unsuspected choroidal or ciliary body melanoma, highlighting the risk of diagnostic delay when pre-operative assessment is inadequate 6. B-scan ultrasonography is a safe, non-invasive, and widely accessible tool that allows visualisation of intraocular structures, and is considered an important tool in the diagnostic work-up of suspected choroidal melanoma, which characteristically appears as a dome or mushroom-shaped mass with low-to-medium internal reflectivity and acoustic hollowing 7, 8. Consequently, a thorough pre-operative ocular examination prior to cataract surgery remains essential, as any abnormal or atypical finding should prompt further targeted investigation, including B-scan ultrasonography, to exclude underlying pathology that might otherwise remain occult until after surgical intervention.
Case Presentation: This case is of a 77-year-old man who was referred to a tertiary ophthalmology centre after an abnormal finding on pre-operative clinical examination by the operating surgeon prompted B-scan ultrasonography of the left eye prior to planned cataract surgery. The scan identified a discrete mass lesion within the posterior segment. Subsequent clinical assessment and further imaging reviewed by ocular oncology at the tertiary centre, confirmed a diagnosis of left choroidal melanoma. Following discussion of treatment options, the patient underwent enucleation of the affected eye.
Conclusion: This case highlights the importance of a thorough pre-operative assessment prior to routine cataract surgery, to identify any serious abnormalities such as a choroidal melanoma. Prompt recognition and referral in integral in preventing further complications.
