Giant choroidal nevi can resemble melanoma of the choroid
Ophthalmology. 2010;117(2):324-333.
Giant choroidal nevi may mimic choroidal melanoma in some cases, according to a study.
"Giant choroidal nevi are rare and can be misdiagnosed as malignant melanoma of the choroid," the study authors said. "Although most giant choroidal nevi in this study remained stable, some transformed into melanoma years after initial presentation, underscoring the importance of life-long regular surveillance."
A choroidal nevus is a benign melanocytic lesion normally less than 5 mm in diameter and less than 2 mm thick. Giant choroidal nevi have a basal diameter of 10 mm or more. Giant choroidal nevi are rare but may resemble melanoma, the authors said.
The retrospective, observational case series included 322 eyes of 322 patients identified with giant choroidal nevi. Median patient age was 63 years (range: 2 years to 91 years). Investigators used indirect ophthalmoscopy to assess nevus basal diameter and ultrasonography to assess thickness. The median follow-up interval was 3.4 years.
Study data showed that median nevus basal diameter was 11 mm and median thickness was 1.9 mm. Involvement of the ciliary body was identified in 22 eyes, and involvement in the foveola was seen in 41 eyes.
Nevus transformation into melanoma was seen in 23 eyes. The rate of transformation of giant nevus into melanoma was 13% at 5 years and 24% at 15 years. Prominent risk factors included close tumor proximity to the foveola and acoustic hollowness on B-scan ultrasonography.
In addition, retinal pigment epithelium atrophy, retinal pigment epithelium hyperplasia, drusen and fibrous metaplasia distinguish giant choroidal nevi from malignant melanoma of the choroid, the authors said.
No patients with presumed nevus transformation into melanoma developed metastasis.
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