Combination of multimodal imaging features predictive of choroidal nevus transformation into melanoma.

Aim: To characterise combinations of multimodal imaging risk factors and predictive value for choroidal nevus transformation into melanoma.

Methods: This is a retrospective review of multimodal imaging features for 3806 choroidal nevi from 1 January 2007 through 1 January 2017. Kaplan-Meier estimates and Cox regression analyses were used to calculate 5-year percentages of growth to melanoma and HR.

Results: Using multimodal imaging, six risk factors predictive of choroidal nevus transformation into melanoma were identified, namely tumour thickness >2 mm, subretinal fluid, symptoms of visual acuity loss to 20/50 or worse, orange pigment, hollow acoustic density and tumour largest basal diameter >5 mm. Kaplan-Meier 5-year estimated tumour growth was found in 1% of nevi with no risk factors, 11% (range 9%-37%) with one factor, 22% (12%-68%) with two factors, 34% (21%-100%) with three factors, 51% (0%-100%) with four factors and 55% (0%-100%) with five factors. HR for growth was 0.1 with no factor, 2.1-7.8 with one factor, 1.8-12.1 with two factors, 4.0-24.4 with three factors, 4.6-170.0 with four factors and 12.0-595.0 with five factors. The highest HR with each combination of two, three, four or five risk factors always included symptoms of visual acuity loss and orange pigment.

Conclusion: Six risk factors for choroidal nevus transformation into melanoma by multimodal imaging have been identified. Risk for transformation into melanoma is 1% when no factors are present, and approaches 100% with specific combinations of three or more risk factors. Understanding how combinations of factors influence risk of transformation into melanoma can guide counselling and treatment decisions.