Ki-67, p53, and p16 expression, and G691S RET polymorphism in desmoplastic melanoma (DM): A clinicopathologic analysis of predictors of outcome.

Abstract

The prognostic role Ki-67, p53, and p16 immunostains and RET (rearranged during transfection) polymorphism in desmoplastic melanoma has not been evaluated. We sought to identify potential prognostic markers. We performed Ki-67, p53, and p16 immunostains on 66 desmoplastic melanomas, and sequenced RET G691 polymorphism and recurrent mutations of 17 cancer genes in 55 and 20 cases, respectively. Recurrence and metastasis were documented in 11 of 66 (17%) and 26 of 66 (39%) patients, respectively. Death was noted in 25 of 55 (45%) patients. Ki-67 expression (≥10%, 43%) correlated with male gender (P = .009), ulceration (P = .002), and Breslow depth (P = .009). p53 Expression (≥50%, 28%) correlated with male gender (P = .002) and head and neck location (P = .0228). Using Kaplan-Meier plots, Ki-67 expression (P = .0425) and mitosis (P = .00295) correlated with overall survival, whereas vascular invasion (P = .0292) correlated with disease progression. There was a significant correlation between Ki-67 and p53 expression (P = .003). RET polymorphism was present in 10 of 46 (22%) cases and inversely correlated with Breslow depth (P = .024). Our study is small and lacks power to perform a multivariate analysis. Although Ki-67 expression correlated with overall survival, additional studies are needed to determine whether Ki-67 would be an independent prognostic marker in addition to the current routine histopathologic assessment.