Digital dermoscopic changes during follow‐up of de‐novo and nevus‐associated melanoma: a cohort study.

Background: Nevus‐associated melanoma (NAM) has been regarded as a distinct biological entity from de‐novo melanoma (DNM); however, static dermoscopy often fails in differentiating these entities. Digital dermoscopic monitoring allows to identify dynamic changes occurring during follow‐up; this may improve diagnostic accuracy and potentially our knowledge on NAM biology. We aimed to define main independent factors associated with NAM diagnosis and those influencing follow‐up time in a population of melanomas excised at follow‐up. Methods: A cohort of melanomas excised at follow‐up was retrospectively and consecutively selected. NAMs and DNMs were compared according to baseline features and main dermoscopic changes occurring during follow‐up. Univariate and multivariable logistic and Cox's regression analysis were performed to respectively define factors associated with NAM diagnosis and those influencing the risk for excision. Results: Eighty‐six melanomas were enrolled, of which 21 (24.4%) were nevus‐associated. During follow‐up NAMs mainly underwent atypical network modifications (47.6%), followed by inverse network (28.6%) and dermoscopic island (23.8%) worsening or appearance. DNMs were also mainly characterized by atypical network modifications (47.7%), however, a significant proportion of cases underwent irregular pigmentation/dots/globules or regression changes (29.2%), which were rarely seen among NAMs. Furthermore, both multivariable logistic and Cox's regression analysis demonstrated a significant association between NAM and a longer follow‐up. Conclusions: We demonstrated that among melanomas excised at follow‐up, different patterns of dermoscopic changes may be found between NAMs and DNMs. This finding, together with the association of NAM with a longer follow‐up time, supports the hypothesis of different biological behavior of these two entities. [ABSTRACT FROM AUTHOR]