Immunophenotypic and Molecular Features of TP53 in Diffuse Large B-Cell Lymphoma (DLBCL)

Abstract

Introduction: Diffuse large B-cell lymphomas (DLBCL) are prevalent among HIV- seropositive patients in Southern Africa. The TP53 gene is the most frequently mutated gene in many tumours. However, there is paucity of data regarding p53 immunoexpression and TP53 mutations in DLBCL. Aims: The study aimed to determine the p53 immunoexpression profile and TP53 gene mutations associated with DLBCL at Chris Hani Baragwanath Academic Hospital (CHBAH). Methods: A retrospective cross-sectional study was conducted using confirmed cases of DLBCL from 2013 to 2017. Immunohistochemistry for p53 protein expression and mutational analysis on TP53 exons 5 to 8 were performed. Results: Sixty patients (N=60) with DLBCL were included with an age range of 22- 88 years and a median age of 45 years (38-54 years). p53 immunoexpression of ≥ 50% was observed in 27 (45%) of cases, of which 19 (70.4%) were HIV seropositive. HIV seropositive patients with p53 protein expression tended to be younger in age, predominantly male with extranodal involvement and also demonstrated a germinal centre (GCB) subtype. TP53 genetic mutations were documented in 10% of the cases and 83.3% thereof expressed p53. TP53 catalogued frameshift mutations were observed in 35 of 50 (70%). Majority of DLBCL mutations were on the NDBL/beta-sheets structural motifs. Conclusion: DLBCL with p53 immunoexpression and TP53 mutations occurred in younger HIV seropositive patients with extranodal involvement and exhibited the GCB subtype.