TP53 mutations in peripheral mature T and NK cell lymphomas: a whole-exome sequencing study with correlation to p53 expression

Peripheral mature T and NK cell lymphomas consist of a heterogeneous group of neoplasms with cytogenetic and molecular diversities. TP53 mutation is involved in the events of tumorigenesis and present in a variety of cancer subtypes. However, TP53 mutation in peripheral mature T and NK cell lymphomas has not been extensively investigated. In this study, 57 formalin-fixed paraffin-embedded samples were collected for whole-exome sequencing and immunohistochemical study. Ten cases had TP53 mutation variant allele frequency (VAF) of more than 5%, predominantly in intestinal T-cell lymphoma (60%), peripheral T cell lymphoma, not otherwise specified (22.2%), and extranodal nasal-type NK/T-cell lymphoma (21.7%). Six of 16 (37.5%) cases with 72Pro homozygous genotype showed higher frequency of TP53 mutation VAF > 5% than did those with 72Arg homozygous genotype (P = .044). To a variable extent, overexpression of p53 was observed in 11 of 56 (19.6%) tumors. The percentage of tumor cells with strong p53 staining was positively correlated with TP53 mutation VAF (R-2 = 0.95, P <.001). TP53 mutation and p53 expression tended to indicate poor prognosis (P = .054 and P = .009, respectively). In conclusion, we demonstrated TP53 mutation and p53 expression in subtypes of peripheral mature T and NK cell lymphomas and found positive correlation of this immunostaing pattern with the status of TP53 mutation. (C) 2018 Elsevier Inc. All rights reserved.