PD-L1 expression in 117 sinonasal mucosal melanomas and its association with clinical outcome

Abstract

BackgroundSinonasal mucosal melanoma (SNMM) is a rare tumour with a poor prognosis. The purpose of this study was to identify independent predictors of outcome in SNMM and to examine the expression of PD-L1 and the relationship between expression and clinicopathological characteristics. MethodsA total of 117 patients with SNMM were reviewed in the Department of Pathology of Beijing Tongren Hospital (115 cases) and Beijing Chuiyangliu Hospital (2 cases) from June 2007 to June 2018. We evaluated the expression of PD-L1 in SNMM and investigated whether there was an association between the expression of the marker and clinicopathological characteristics. ResultsSex, age, side, location, size, histological type, melanin particles, nuclear fission and tumour infiltrating lymphocytes (TILs) were not significantly related to survival. The median survival times at the T3, T4a, and T4b stages were 23, 19, and 6 months, respectively. The difference between overall survival (OS) and AJCC stages was statistically significant. The tumour cells (TCs) were PD-L1 positive in 14/117 (12.0%) cases, and tumour-associated immune cells (ICs) were PD-L1 positive in 23/117 (19.7%) cases. A statistically significant correlation was observed between the positive expression rate of PD-L1 in ICs and TILs grading; however, there was no significant correlation between the positive expression rate of PD-L1 in TCs and TILs grading. ConclusionThe AJCC stages were the only independent predictors of survival. There was no correlation between the positive expression rate of PD-L1 and OS. A statistically significant correlation was observed between the positive expression rate of PD-L1 in ICs and TILs grading.