Analysis of dermoscopy changes of blue nevi in digital follow-up
Background: Blue nevi are benign dermal melanocytic proliferations that are often easy to recognize clinically. Rarely, these lesions can display atypical findings, such as progressive growth, suggesting the rise of a malignant blue nevus or mimicking cutaneous metastases from melanoma. Objective: The objective of this study was to describe the clinical evolution of blue nevi over time, to assess the need for monitoring these lesions and to evaluate the molecular profile of blue nevi displaying an atypical behavior. Methods: We conducted a retrospective cohort study of 103 patients who were followed between December 1998 and November 2019. An active learning artificial intelligence algorithm was used to identify blue nevi based on its dermoscopic pattern from the database of two digital epiluminescence devices. Change in area of each lesion was calculated with a segmentation neural network. To further characterize the lesions exhibiting progressive growth, we obtained the molecular genomic profiling by next-generation sequencing. Results: Of the 279 initially identified lesions, among a total of 398,543 images, 123 blue nevi from 103 individuals were included. A total of 108 (87.8%) lesions were segmented, of which 99 (91.7%) were considered stable. Of the 9 (8.3%) growing blue nevi identified, 2 (1.85%) presented a progressive growth with a percentual change of >100% and were excised and further characterized. The studied growing blue nevi turned out to be cellular blue nevi, presented with a low tumor mutation burden and GNAQ c.626A>T alteration was identified in both lesions. Conclusions: In this cohort with extensive follow-up, we observed that the majority of blue nevi remain stable during their evolution. Rarely, they can show progressive growth, although histopathological or molecular signs of malignancy have not been identified in these lesions. Accordingly, periodic monitoring of blue nevi is not required.