Supplementary Material for: The natural evolution of nevi with peripheral globules

Background: Peripheral globules (PG) in melanocytic lesions represent a concerning dermoscopic feature, since they might be present in growing nevi and melanomas. Their natural evolution has not been fully elucidated and an age-based management approach has been recommended. Objectives: To calculate the growth rate of lesions with PG and investigate possible association with age, sex, location and the global dermoscopic pattern. Methods: We retrospectively selected the lesions of interest from a cohort of Caucasian patients who underwent sequential digital dermoscopy monitoring. Lesions with PG distributed at 75% or more of their circumference with available follow up images or histopathologic report were included. The surface area was automatically calculated with the help of an incorporated tool used in the acquisition of the images. The images were also evaluated by independent investigators for the presence of pre-defined criteria. Growth-curve models were used to assess the growth rate. The outcome variable was the area of nevi in mm2 and scatterplots with Lowess curves were used to present the mean change of nevi during follow up. Results: A total of 208 lesions from 98 patients with a median age of 36 years (range 15-75) were included. The median follow-up time was 18 months (range 4-48). The mean growth rate for all nevi was 0.16 mm2/month (95% CI, 0.14 – 0.18, p<0.001) ranging from -0.29 to 0.61 mm2/month. The growth rate was higher in nevi with a homogeneous dermoscopic pattern (p<0.001). The number of peripheral globules during follow up varied from increasing to complete disappearance. None of the lesions developed any melanoma-specific structure at follow up. Conclusion: Nevi with PG grew at a mean rate of 0.16mm2/month and the growth rate was independent of age, gender or anatomic location. Nevi with homogeneous pattern demonstrated the highest growth rate in our cohort. None of the monitored nevi with PG developed melanoma-specific criteria at follow up.