Melanoma of the posterior uvea (ciliary body and choroid) is the most common malignancy encountered by ophthalmologists, and its epidemiology and clinical features are well known (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29). It arises from melanocytes in the posterior uveal tract. The epidemiology and general aspects of uveal melanoma are discussed in detail elsewhere. Its annual age-adjusted incidence in the United States is about 6 cases per 1 million population (2,10,29). It is decidedly more common in adult whites and is uncommon in children and in dark-skinned individuals (9, 10, 11, 12, 13). Predisposing conditions for uveal melanoma include ocular melanocytosis, white race, and possibly the dysplastic nevus syndrome. The clinical features of posterior uveal melanoma are well established and are described mainly in textbooks and a few descriptive articles (1, 2, 3). It is important for ophthalmologists to be familiar with the clinical features of ciliary body and choroidal melanoma because this neoplasm can cause blindness and death.

In contrast to iris melanoma, ciliary body melanoma can often attain a larger size before it is recognized clinically. However, it is frequently associated with external ocular signs that suggest the underlying diagnosis. The most important sign is one or more dilated episcleral blood vessels (sentinel vessels). A second sign is an epibulbar pigmented lesion characteristic of transcleral extension of the tumor (2,7). When the pupil is dilated widely, the ciliary body tumor can be visualized in the affected area as a dome-shaped mass. Less frequently, it can assume a diffuse circumferential ring growth pattern (ring melanoma) (8). Ciliary body melanoma can impinge on the lens, causing subluxation and cataract. It can grow posteriorly into the choroid (ciliochoroidal melanoma) and anteriorly into the anterior chamber angle and iris (iridociliary melanoma). It can infiltrate the trabecular meshwork, causing secondary glaucoma.

Choroidal melanoma usually presents as a sessile or dome-shaped mass located deep to the sensory retina. A smaller posterior choroidal melanoma may have surface orange pigment at the level of the retinal pigment epithelium (1, 2, 3, 4). A secondary nonrhegmatogenous retinal detachment frequently occurs. In contrast to a rhegmatogenous detachment, in which the subretinal fluid does not shift, the fluid with melanoma and other tumors shifts with positional changes of the patient’s head. Occasionally, a choroidal melanoma can be partly or entirely nonpigmented. When the tumor is amelanotic, blood vessels in the tumor are visible ophthalmoscopically. With continued growth, a choroidal melanoma can rupture Bruch’s membrane and assume a mushroom shape. When that occurs, the tumor has a tendency to bleed, and vitreal or subretinal blood can sometimes obscure a view of the underlying tumor. Choroidal melanoma can also assume a diffuse growth pattern with only minimal elevation of the tumor (4,5). In some instances, ciliary body or choroidal melanoma can cause total cataract, secondary glaucoma, and extraocular extension into the orbit. Such tumors are generally larger and carry a worse prognosis (6,7).

In unusual instances, choroidal melanoma has been documented to undergo spontaneous regression (27,28). A spontaneously regressed melanoma generally is relatively flat and has amelanotic areas that represent regions of necrosis in the tumor. Areas of retinal pigment epithelium alterations suggest that prior active retinal detachment has resolved. Another typical feature is a well-defined overlying area of retinoschisis (intraretinal cyst), at the base of which is a characteristic crater in the tumor. Melanomas with such necrosis can rarely recur as an active tumor after months or years (27,28).

Important risk factors for growth and metastasis of small melanocytic choroidal lesions have been identified (24,25). Statistical risk factors for growth include tumor thickness >2 mm at initial diagnosis, overlying orange pigment, subretinal fluid, proximity to the optic disc, and presence of symptoms. Clinical factors predictive of possible eventual metastasis include tumor thickness >2 mm at initial diagnosis, tumor proximity to the optic disc, presence of symptoms, and documented enlargement. These should be determined and used in counseling the patient and in determining whether a lesion should be observed periodically or actively treated (24,25).

Although dilated episcleral blood vessels usually signify an underlying ciliary body melanoma, they can occasionally be seen with other, less common tumors like ciliary body metastasis, leiomyoma, schwannoma, melanocytoma, and epitheliomas (adenomas) of the nonpigmented or pigmented ciliary epithelium. On rare occasions, a dilated episcleral vessel is seen as a normal variant with no evidence of a ciliary body mass.

Ciliary body melanoma can frequently extend through emissary channels to appear in the episcleral tissues, sometimes forming an extraocular mass. It is more likely to occur with larger, more aggressive tumors, particularly those that grow in a ring pattern. In rare instances, anterior extraocular extension can invade the overlying conjunctiva. Transcleral extension usually imparts a worse systemic prognosis.

A ciliary body melanoma can grow through the iris root and appear as a mass in the peripheral portion of the iris, simulating a primary iris tumor. Unlike a primary iris melanoma, anterior extension of a ciliary body melanoma tends to pass through the iris root and produce a tumor-induced iridodialysis.

Ciliary body melanoma generally appears as a dome-shaped pigmented mass that can encroach on the lens, producing subluxation and cataract. It can extend posteriorly into the choroid (ciliochoroidal melanoma). Occasionally it grows in a ring rather than a nodular pattern.