"Paradoxical" p16 overexpression in cutaneous melanoma: Molecular and immunohistochemical analysis of a rare phenomenon with a focus on cell cycle regulatory molecules.

p16 overexpression is a rare event, occurring in advanced-stage, clinically- and histologically-heterogeneous CM. These lesions may be classified into three different groups based on CCRM expression and mutational profiles (including TP53 mutation). The analysis of CM with zonal p16 overexpression suggests that, at least in a subset of cases, this phenomenon could represent a sign of "molecular progression" due to the acquisition of additional genetic mutations and/or modifications of the CCRM profile.