Purpose: Evaluation of clinical features and natural course of giant choroidal nevi (diameter ≥10 mm). Design: Retrospective observational case series. Participants: We included 322 eyes of 322 patients. Methods: Clinic-based study of tumor features, tumor outcome, and vision outcome. Kaplan-Meier analysis was used to assess time to transformation into melanoma. Cox proportional hazards regressions evaluated clinical factors predictive of nevus transformation into melanoma and nevus-related decreased vision (defined as <20/20 and unrelated to other eye pathology). Main Outcome Measures: Transformation of giant choroidal nevus into melanoma and nevus-related decreased vision. Results: A medical record review of 4100 patients diagnosed with choroidal nevus identified 322 (8%) giant choroidal nevi. Median nevus basal diameter was 11 mm (range, 10-24). Median thickness was 1.9 mm (range, 0-4.4). Related retinal findings included drusen overlying nevus (n = 261 [81%]), subretinal fluid (n = 26 [8%]), orange pigment (n = 4 [1%]), retinal pigment epithelial (RPE) detachment (n = 6 [2%]), hyperplasia (n = 48 [15%]), fibrous metaplasia (n = 48 [15%]), atrophy (n = 63 [20%]), or trough (n = 6 [2%]). Kaplan-Meier analysis estimated transformation into melanoma in 13% at 5 years and 18% at 10 years. Multivariate analyses revealed factors predictive of transformation into melanoma including involvement or close proximity to the foveola (P = 0.017) and acoustic hollowness (P = 0.052). Nevus-related decreased vision was found in 2.2% of eyes at initial visit and 3.7% at final visit (median 41 and mean 61 months follow-up). Factors associated with nevus-related decreased vision at initial visit included subretinal fluid (P = 0.001), involvement or close proximity to foveola (P = 0.005), RPE detachment (P = 0.033), and nevus-related choroidal neovascular membrane (P = 0.044). Factors predictive of nevus-related decreased vision at final visit included involvement or close proximity to the foveola (P = 0.001) and presence of symptoms at the initial visit (P = 0.032). Conclusions: Giant choroidal nevi can clinically resemble choroidal melanoma but show features of chronicity, such as overlying drusen and RPE alterations. Over time, 18% transformed into melanoma, underscoring the importance of life-long surveillance. Financial Disclosure(s): The authors have no proprietary or commercial interest in any of the materials discussed in this article.
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