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Ophthalmic Pearls

ONCOLOGY

Distinguishing a Choroidal From a Choroidal

by albert cheung, ingrid u. scott, md, mph, timothy g. murray, md, and carol l. shields, md edited by ingrid u. scott, md, mph, and sharon fekrat, md

horoidal nevi are benign ing light-colored eyes (blue or gray), 1 melanocytic of the fair and a propensity to burn posterior uvea. In the United when exposed to light.2 States, their prevalence rang- This susceptibility may be secondary es from 4.6 percent to 7.9 per- to reduced number of Ccent in Caucasians.1 By comparison, () in the choroid and reduced choroidal melanoma is rare, manifest- melanin in the retinal pigment epithe- ing in approximately six in 1 million lium, which provides this population Caucasian individuals. with less protection from UV light. of and death from cho- Lighter skin color also could be indica- roidal melanoma have been shown to tive of reduced or different melanin. correlate with increasing basal diam- Other risk factors for choroidal eter and increasing thickness of the melanoma include nevi and , 2 . Thus, early detection is impor- which are viewed as markers of a pre- tant. In addition, making the correct disposing phenotype and environmen- diagnosis of choroidal nevi in a timely tal UV light exposure. The number fashion protects patients against the of common cutaneous nevi, atypical visually damaging effects of unneces- cutaneous nevi, cutaneous freckles sary treatment. and iris nevi have all been found to be associated with an increased risk of Symptoms choroidal melanoma.3 Choroidal nevi, which typically are Environmental risk factors. These found on routine dilated fundus ex- include chronic sunlight exposure and amination, usually are asymptomatic. arc welding.4 Studies examining the as- However, they can be associated with sociation between choroidal melanoma DIFFERENTIATION. (1) Choroidal nevus symptoms such as central and periph- and UV light exposure using surrogate with drusen. (2) Choroidal melanoma eral visual loss secondary to subretinal markers (such as birth latitude, out- with orange pigment and subretinal fluid, cystoid retinal edema or, rarely, door leisure activities or occupational fluid. choroidal neovascularization. sunlight exposure) have been incon- Choroidal melanoma also tends to sistent.4 associated dormant features, such as be asymptomatic, although it is more overlying retinal pigment epithelial likely to be symptomatic than a benign Differentiation and Documentation alterations and drusen; and suspicious nevus. Symptoms of a choroidal mela- Differentiating between benign choroi- features, including subretinal fluid and noma may include decreased vision, dal nevi and small malignant melano- orange pigment. flashes or floaters. mas can be challenging. Distinguishing features. Choroidal Shared features. Choroidal nevi nevi tend to have clearly defined mar- Melanoma Risk Factors and choroidal melanoma can show gins and to be flat or slightly elevated, Host risk factors. Significant risk fac- several overlapping features, including and they remain stable in size. Over tors for choroidal melanoma include tumor size; color, which may be either time, choroidal nevi display features

carol l. shields, md being of Caucasian ethnicity and hav- pigmented or nonpigmented; location; such as overlying drusen as well as

eyenet 39 Ophthalmic Pearls retinal pigment epithelial atrophy, hy- mas. Other echographic features that treatment due to their increased risk of perplasia or fibrous metaplasia. are suspicious for melanoma include developing melanoma. In contrast, choroidal excavation of choroidal tissue, sound are more likely to show signs of activity attenuation, orbital shadowing and Conclusion such as relatively indiscrete margins, spontaneous vascular pulsations.8 Differentiating between choroidal nevi irregular or oblong configuration, Echographic follow-up for at least 1.5 and choroidal melanomas can be chal- overlying subretinal fluid and orange years may be necessary to differentiate lenging, but knowing which risk fac- pigment, and abruptly elevated edges. between suspicious nevi and melano- tors are associated with an increased Documentation of growth. Most mas. risk of developing melanoma will aid authorities agree that documentation the clinician in making the correct di- of growth over a relatively short period Management of Choroidal Nevi agnosis in a timely fashion and manag- of time, such as one to two years, is a Management of a choroidal nevus is ing patients appropriately. convincing characteristic of a mitoti- determined by its risk of transforming cally active melanoma. However, it is into a choroidal melanoma. Mr. Cheung is a medical student and Dr. ideal to detect choroidal melanoma be- By risk factors. From studies using Scott is professor of ophthalmology and public fore the recognition of growth, as doc- the TFSOM-UHHD risk factors, cho- health sciences; both are at Penn State College umented growth imparts an almost roidal melanocytic tumors that dis- of Medicine in Hershey, Pa. Dr. Murray is eightfold greater risk for metastasis.5 played none of the risk factors had a 3 professor of ophthalmology at Bascom Palmer On the other hand, slow growth of 0.5 percent chance for growth at five years Eye Institute in Miami. Dr. Shields is professor mm over many years or decades may and most likely represented nevi.9 For of ophthalmology and associate director of the simply reflect the natural progression lesions that display one factor, impart- ocular service at Wills Eye Institute of a benign choroidal nevus.6 ing a 38 percent chance for growth, in Philadelphia. observation is a reasonable option, Risk of especially if the lesion is in a visually 1 Singh AD et al. Ophthalmology. 2005; Choroidal nevi rarely evolve into ma- important location. Lesions with three 112(10):1784-1789. lignant melanoma; the annual rate of or more factors will show growth in 2 Weis E et al. Arch Ophthalmol. 2006;124(1): malignant transformation is estimated more than 50 percent of cases. Such 54-60. to be 1 in 8,845.1 The rate of transfor- lesions likely represent small choroidal 3 Weis E et al. Ophthalmology. 2009;116(3): mation increases with age; it has been melanomas; and early intervention 536-543, e2. estimated that by age 80, the risk for may be warranted, as they occasionally 4 Shah CP et al. Ophthalmology. 2005;112(9): malignant transformation of a choroi- lead to metastasis. 1599-1607. dal nevus is 0.78 percent.7 By lesion size. Some clinicians 5 Shields CL et al. Ophthalmology. 1995; Although nevus thickness has been suggest observation for lesions smaller 102(9):1351-1361. reported to be the most important risk than 2 mm; lesions larger than 2 mm 6 Shields CL et al. Arch Ophthalmol. 2009; factor for malignant transformation, but smaller than 2.5 mm may be man- 127(8):981-987. other factors are also predictive. The aged based on clinical risk factors, 7 Kivelä T, Eskelin S. Ophthalmology. 2006; mnemonic “To Find Small Ocular with either close observation or imme- 113(5):887-888, e1. Melanoma Using Helpful Hints Daily” diate treatment. 8 Pavlin CJ, Foster FS. “Ultrasound Biomi- (TFSOM-UHHD) has been proposed.6 Recommended follow-up. Patients croscopy of the Eye,” in Ultrasound of the Eye This stands for thickness greater than 2 with choroidal nevi who show no sus- and Orbit, 2nd ed. (St. Louis: Mosby; 2002). mm, subretinal fluid, symptoms, orange picious features require no treatment. 9 Shields CL et al. Arch Ophthalmol. 2000; pigment present, margin within 3 mm During the first year, they should be 118(3):360-364. of the optic disc, ultrasonographic hol- monitored twice; subsequently, they lowness (versus solid/flat), absence of should be evaluated annually as long halo and absence of drusen.6 (A halo as the nevi remain stable. Although Got Pearls? refers to a pigmented choroidal nevus the link between UV light exposure INTERESTED IN SHARING TIPS WITH surrounded by a circular band of de- and choroidal melanoma has not been YOUR COLLEAGUES? pigmentation.) proved, sunglasses could possibly re- WRITE A PEARLS ARTICLE! Low to medium internal reflectiv- duce ocular melanoma risk. ity, often compatible with acoustic Patients who have one or two risk Ophthalmic Pearls, EyeNet Magazine hollowness on B-scan echography, factors for malignant transformation 655 Beach Street has been correlated with choroidal should be monitored every four to six San Francisco, CA 94109 melanoma. Echographically measured months. Patients with nevi and three [email protected] thickness of at least 2 mm and a largest or more suspicious features should be Writers guidelines basal diameter of at least 7 mm can be evaluated at an experienced center for provided upon request. helpful in identifying small melano- management alternatives and possible

40 february 2012