P008 Beyond 1 year: extended-interval comparison of digital dermoscopic images increases melanoma detection rates in a high-risk melanoma cohort

Abstract

Dermoscopic monitoring of atypical pigmented lesions traditionally assesses interval changes between current and prior dermoscopic images. In 2025, in our high-risk melanoma cohort we extended image comparison from 1 year to the maximum retrospective interval image available (up to 6 years). The aim of the study was to evaluate the impacts of short (1 year) vs. long (1–6 years) intervals for dermoscopic comparison on excision rates, melanoma detection and diagnostic distribution. A retrospective observational service evaluation was undertaken between 2019 and 2025. In 2025 dermoscopic images were compared with the oldest dermoscopic image of the lesion. Total-body photography and sequential digital dermoscopy were performed (ATBM Classic and Medicam 1000; FotoFinder Systems, Bad Birnbach, Germany). Over 6 years, 274 patients underwent 1166 visits with 464 lesions excised. In 2025 extended dermoscopic comparison (> 1 year) was available in 66% of cases. The excisions per visit increased from 21.4% in 2024 to 46.3% in 2025, but the proportion of multiple-lesion excisions remained broadly stable at 51% (2024 and 2025). The increase in excisions was diagnosis specific. Melanoma detection per visit increased significantly (from 3.1% to 14.7%, P < 0.001), and the absolute number of melanomas rose from 8 in 2024 to 40 in 2025. Despite increased excision activity, the melanoma-to-nonmelanoma excision ratio remained broadly stable. Although excisions of dysplastic naevi increased and those of compound naevi decreased, figures were comparable with earlier years. The mean Breslow thickness remained low throughout (overall mean 0.36 mm) and was lowest in 2025 (0.29 mm). We show that in a high-risk melanoma cohort, comparing dermoscopic images over longer timeframes increased sensitivity to lesion change, resulting in a marked rise in melanoma detection without evidence of overexcision. These findings support the value of extended retrospective comparison in digital mole mapping services and highlight the importance of access to such services for high-risk populations.