Most uveal melanomas are initially completely asymptomatic. As the tumor enlarges, it may cause distortion of the pupil (iris melanoma), blurred vision (ciliary body melanoma), or markedly decreased visual acuity caused by secondary retinal detachment (choroidal melanoma). Serous detachment of the retina may occur. If extensive detachment occurs, secondary angle-closure glaucoma occasionally develops. Clinically, several lesions simulate uveal melanoma, including metastatic carcinoma, posterior scleritis, and benign tumors, such as nevi and hemangiomas.
Anatomy of the eye.
Careful examination by an experienced clinician remains the most important test to establish the presence of intraocular melanoma. It is not possible to distinguish a small uveal melanoma from a nevus. Small uveal lesions are often observed for growth to make a diagnosis of melanoma. Clinical findings that may help to identify melanoma include:
- Tumor thickness of more than 2 mm.
- Subretinal fluid.
- Visual symptoms.
- Orange pigment on the tumor surface.
- A tumor margin touching the optic disc.
Ancillary diagnostic testing, including fluorescein angiography and ultrasonography, can be extremely valuable in establishing and/or confirming the diagnosis. In a large, retrospective, single-center series of 2,514 consecutive patients with choroidal nevi, the progression rates to melanoma at 5, 10, and 15 years were 8.6%, 12.8%, and 17.3%, respectively.
A number of factors influence prognosis. The most important factors include the following:
- Cell type. (Refer to the Cellular Classification of Intraocular [Uveal] Melanoma section of this summary for more information).
- Tumor size.
- Location of the anterior margin of the tumor.
- Degree of ciliary body involvement.
- Extraocular extension.
Several additional microscopic features can affect the prognosis of intraocular melanoma, including:
- Mitotic activity.
- Lymphocytic infiltration.
- Fibrovascular loops (possibly).
Cell type is the most commonly used predictor of outcome following enucleation, with spindle-A cell melanomas carrying the best prognosis and epithelioid cell melanomas carrying the least favorable prognosis.[1,4,9] Nevertheless, most tumors have an admixture of cell types, and there is no clear consensus regarding the proportion of epithelioid cells that constitutes designation of a tumor as mixed or epithelioid.