Slow enlargement of choroidal nevi: a long-term follow-up study

Choroidal nevi are generally considered to be stable lesions, and growth of a choroidal nevus is usually believed to be a sign of malignant transformation. We performed this study to determine whether choroidal nevi enlarge over a long period of follow-up without undergoing malignant transformation.

Retrospective observational case series.

A total of 278 patients with 284 nevi who had at least 7 years of photographic follow-up without clinical signs of transformation into melanoma were included in the study.

Data on demographic and clinical information were extracted from patients' charts. Detailed fundus drawings and color fundus photographs were reviewed and compared for evidence of enlargement.

Nevus enlargement without clinical evidence of transformation into melanoma.

Of the 278 patients, 69% were female and more than 99% were White with a median age at presentation of 57 years (range, 4-87 years). The largest nevus basal diameter was a median of 5 mm (range, 0.5-14 mm), and the median thickness was 1.5 mm (range, 0.1-3.6 mm). Only 14 nevi (5%) had subretinal fluid outside the nevus, and 6% showed overlying orange pigment. Overlying retinal pigment epithelial alterations included drusen (61%), atrophy (6%), hyperplasia (10%), and fibrous metaplasia (6%). Of 284 nevi, 31% showed slight enlargement over a mean follow-up of 15 years. The median increase in diameter was 1 mm (mean, 0.9 mm; range, 0.2-3.0 mm), and the median rate of enlargement was 0.06 mm/yr (mean, 0.06 mm/yr; range, 0.01-0.36 mm/yr). None of the lesions that enlarged developed new risk factors that are generally associated with malignant transformation. Frequency of enlargement was 54% in patients aged less than 40 years and 19% in patients aged more than 60 years. On multivariate analysis, younger patient age was the only factor predictive of nevus enlargement (P<0.001).

With long-term follow up, 31% of choroidal nevi showed slight enlargement without clinical evidence of transformation into melanoma. The frequency of enlargement was inversely related to patient age.