Q4 LONG ANSWER 10M ★ High-yield

Describe the tumours of the uveal tract.

Ophthalmology · 3rd Professional

Choroidal Melanoma

Uveal melanoma is the commonest primary intraocular malignancy of adults (as retinoblastoma is of children); 90% arise in the choroid, and the remainder in the ciliary body and iris
Risk factors — fair skin and light iris; oculodermal melanocytosis (naevus of Ota); the BAP1 tumour predisposition syndrome; dysplastic naevus syndrome; and increasing age. It is rare in dark-skinned populations, and therefore much less common in India than in Europe
Presentation — frequently asymptomatic and found incidentally; otherwise blurred vision, field loss, floaters or photopsia; and rarely pain from secondary glaucoma or necrosis

Feature	Description
Shape	A dome-shaped pigmented or amelanotic mass; and where the tumour ruptures BRUCH’S membrane it assumes the classical collar-stud or mushroom shape.
Orange pigment	Lipofuscin over the tumour surface — an important sign of activity and a risk factor for growth
Subretinal fluid	An exudative detachment, often shifting with posture
Ultrasound (A-scan)	Low to medium internal reflectivity — characteristic, and distinguishing it from a haemangioma (high reflectivity) or metastasis
Ultrasound (B-scan)	An acoustically hollow mass with choroidal excavation and orbital shadowing
The "TFSOM" risk factors	To Find Small Ocular Melanoma: thickness over 2 mm; subretinal fluid; symptoms; orange pigment; and margin within 3 mm of the disc. Used to decide whether a pigmented lesion is a naevus to be watched or a melanoma to be treated

Other Uveal Tumours

Tumour	Features
Choroidal naevus	Very common, present in perhaps 5 to 10% of the population. Flat or minimally elevated, less than 5 mm across and 2 mm thick, slate-grey, with overlying drusen indicating chronicity, and NO subretinal fluid or orange pigment. Asymptomatic. Managed by photography and observation, using the TFSOM criteria to detect transformation
Choroidal metastasis	The commonest intraocular malignancy overall. From the breast in women and the lung in men; also gastrointestinal, renal and prostate. Appears as a creamy-yellow, plateau-shaped (flat) lesion at the posterior pole, frequently multiple and bilateral, with subretinal fluid. High internal reflectivity on A-scan. In a third of cases the eye is the first presentation of the malignancy, so a systemic search is mandatory. Treated with external beam radiotherapy and systemic therapy
Choroidal haemangioma	Circumscribed — a solitary orange-red dome at the posterior pole, with high internal reflectivity; or diffuse — associated with STURGE-WEBER syndrome, giving a "tomato ketchup" fundus with a deep red colour compared with the fellow eye. Treated with photodynamic therapy or radiotherapy if there is subretinal fluid
Iris lesions	Iris naevus — flat and stable; iris melanoma — raised, over 3 mm, with prominent vessels, ectropion uveae, sectoral cataract, and seeding into the angle with raised pressure; and LISCH nodules — multiple bilateral tan hamartomas which are pathognomonic of neurofibromatosis type 1
Melanocytoma	A deeply pigmented, benign tumour characteristically at the optic disc, commoner in dark-skinned individuals; benign but requires monitoring for rare malignant transformation

Choroidal Naevus Compared with Melanoma

Feature	Naevus (benign)	Melanoma
Thickness	Less than 2 mm	Greater than 2 mm
Diameter	Usually under 5 mm	Larger, and growing
Subretinal fluid	Absent	Present
Orange pigment (lipofuscin)	Absent	Present
Overlying drusen	Present — a sign of chronicity and reassuring	Usually absent
Symptoms	None — found incidentally	Blurring, field loss, photopsia
Margin to the optic disc	Any distance	Within 3 mm is a risk factor
A-scan reflectivity	High or medium	Low to medium; acoustically hollow with choroidal excavation
Management	Photograph and observe	Brachytherapy, proton beam or enucleation; and lifelong liver surveillance

Applied Aspects

Apply the TFSOM criteria to every pigmented choroidal lesion; thickness, fluid, symptoms, orange pigment and proximity to the disc distinguish a naevus to watch from a melanoma to treat
Look for drusen over the lesion; they indicate a long-standing benign naevus and are reassuring
Get an A-scan; low internal reflectivity supports melanoma and high reflectivity supports haemangioma or metastasis, and it costs nothing

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