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Ocular melanoma (iris, ciliary body, choroid)
- Caucasian race of Northern European ancestry
- Choroidal nevus
- Nevus of Ota
The majority of ocular melanomas are oval shaped nodules despite the classically described collar-button shape. Alternatively, melanomas rarely present as a diffuse pattern with minimal height. Pigmentation varies from amelanotic to black and affects intraocular tissues containing melanin such as the choroid, iris, and ciliary body.
The modified Callender system describes cell types as: spindle cell, mixed cell (containing epitheliod), and necrotic. Other findings consistent with melanoma include: large nucleolar size, higher mitotic rate, aneuploidy, vascularity, lymphocyte infiltration, and overlying retinal degeneration.
Ocular melanoma can cause significant ocular morbidity including: serous retinal detachment, choroidal neovascularization, and melanomalytic glaucoma.
There are no known prevention measures since the basic etiology remains unknown.
Patients with ocular melanoma are often asymptomatic or report nonspecific symptoms including photopsias or vision loss if the tumor or exudative detachment encroach on the fovea. Most patients are middle aged or older and Caucasian.
The examination includes detailed ophthalmoscopy and ultrasound. Fluorescein angiography can be useful in evaluating lesions that simulate ocular melanoma but is not usually diagnostic for melanoma.
The classic description of a choroidal melanoma is a pigmented collar button-shaped tumor often associated with a serous retinal detachment; however, melanomas can vary from amelanotic to dark brown and from fusiform to collar-button. High risk characteristics suggestive of a melanoma include orange lipofuscin pigment, height greater than 3 mm, and subretinal fluid.
- Blurred vision (central or peripheral)
Ocular melanoma is typically diagnosed clinically by appearance on ophthalmoscopy and ultrasound. Biopsy is generally reserved for equivocal cases.
Standardized Echography (Ultrasound)
A-scan (time amplitude-mode)
8 MHz transducer: A-scan echography provides a one-dimensional assessment of the distance between ocular structures and relative reflectivity within the structures. Tumor height is measured as the distance between the spikes representing the tumor surface and the inner- sclera.
B-scan (brightness mode)
10 MHz transducer: B-scan echography is a two-dimensional representation of the posterior segment. This mode is valuable in detecting the tumors and assessing basal measurements.
Characteristics of ocular melanoma using Standardized Echography include: collar button (mushroom) shape, low to medium internal reflectivity, regular internal structure, and internal vascularity. (Ossoinig, 1979)
Other resources for anterior segment assessment:
- Ultrasound biomicroscopy (UBM)
- 20 Mhz B-scan
- Anterior segment optical coherency tomography
No laboratory tests are helpful in diagnosing ocular melanoma.
- Choroidal hemangioma
- Metastatic carcinoma
- Disciform lesions
- Choroidal hemorrhage
- Choroidal osteoma
- Posterior nodular scleritis
- Ampulla of vortex vein
- Congenital hypertrophy of the retinal pigment epithelium
Management options include observation, laser photocoagulation, transpupillary thermotherapy, radiotherapy, local resection, or enucleation.
Chemotherapy and immunotherapy are not used for local control of ocular melanoma.
Medical follow up
Patients are followed periodically after treatment with follow-up clinical examinations and ultrasound to ensure appropriate resolution of the tumor.
Ocular melanoma is generally treated surgically using one of the approaches described in 3.1 with radiotherapy and enucleation used most frequently.
Surgical follow up
Specific follow-up depends on the individual clinician; however, most ocular oncologists will follow the patients periodically to monitor for treatment failure, complications, and ensure appropriate metastatic screening.
Complications universal to all treatment modalities include local treatment failure. Treatment specific complications include radiation retinopathy and neuropathy, neovascular glaucoma, cataract, hemorrhage, and diplopia for radiotherapy. Infection and tissue dehiscence are occasionally observed after enucleation.
Local treatment rates are high after radiotherapy and enucleation. However, metastatic disease was diagnosed at a 25% and 34% rate at 5-years and 10-years respectively in the Collaborative Ocular Melanoma Study (COMS) with the liver affected 89% of the time. The mortality rate after diagnosis of metastatic disease was 80% at 1 year and 92% at 2 years. (Diener-West, 2005)
Diener-West M, Reynolds SM, Agugliaro DJ, et al. Development of metastatic disease after enrollment in the COMS trials for treatment of choroidal melanoma: Collaborative Ocular Melanoma Study Group Report No 26. Archives of Ophtalmology. 123(12):1639-43.2005.
Ossoinig, KC. Standardized echography: basic principles, clinical applications, and results. International Ophthalmology Clinics. 19:127-210. 1979.