Sequential digital dermoscopic imaging (SDDI) compares surface microscopy images of skin lesions over multiple time points. We utilized a retrospective SDDI cohort to investigate the development of dermoscopic features associated with malignancy in melanoma in situ (MIS). A total of 124 in situ melanomas were assessed from 110 Caucasian patients aged ≥18 years, with ≥2 serial images obtained between 1999 and 2017 and followed for a mean 41 months (3-142). As a positive control group, 58 invasive melanomas from 53 patients were also reviewed. Change in MIS size or number of colours correlated to time (both p
