Nevus-associated melanoma: An observational retrospective study of 22 patients evaluated with dermoscopy and reflectance confocal microscopy.

ABSTRACT

BACKGROUND: The frequency of nevus-associated melanoma (NAM) has been estimated to be 29% of diagnosed melanomas. MATERIALS AND METHODS: This is an observational retrospective study of 22 cases of NAM diagnosed in the Universitary Hospital Alcorcón between September 2011 and 2018. The main objective was to analyze dermoscopic and RCM features of NAM. We also studied if there was an association between any dermoscopic or RCM parameter and Breslow depth. RESULTS: The most frequent dermoscopic characteristics were multicomponent pattern (50%), multifocal pigmentation (45.5%), atypical network (59.1%), and blue-gray regression structures (77.3%). RCM evidenced pagetoid cells in 95.5% melanomas (abundant in 59.1%), non-edged dermal papillae in 86.4%, atypical cells at the dermal-epidermal junction in 90.9%, and atypical junctional nesting in 81.8%. Deeper Breslow index was associated with red color (mean Breslow 0.65 vs 0.37 in melanomas without red, P = 0.035), shiny white streaks (0.85 vs 0.38, P = 0.041), abundant pagetoid cells (0.68 vs 0.26, P = 0.017), and non-edged papillae (0.59 vs 0.00, P = 0.014). CONCLUSION: RCM is a valuable tool for diagnosing NAM. Even it is very difficult to differentiate NAM from DNM both with dermoscopy and RCM, RCM can help us to detect remnants of a preexisting nevus and estimate Breslow depth.