Immune evasion-related extranodal large B-cell lymphoma: A report of six patients with neoplastic PD-L1-positive extranodal diffuse large B-cell lymphoma.

We identified six patients with Epstein-Barr virus (EBV)-negative extranodal diffuse large B-cell lymphoma (DLBCL) and immunohistochemical expression of PD-L1 on their tumor cells by examining 283 DLBCL cases with the PD-L1 SP142 clone between 2015 and 2017. They consisted of two men and four women with a median age of 71 years, and were examined in an autopsy (n = 1) and biopsies from the adrenal gland (n = 2), skin (n = 1), pelvic cavity (n = 1), and kidney (n = 1). All showed a monomorphic population of large transformed B-cells leading to diagnoses of DLBCL with two intravascular large B-cell lymphoma (IVLBCL) and one de novo CD5+ type and were featured by an invariable immunephenotype: CD3-, CD20+, BCL-2+, and MUM1+. In addition, CD5 and CD10 were each detected in one case. All cases expressed PD-L1 on >10% to >90% of tumor cells, which was confirmed with two other PD-L1 antibodies (E1J2J and 28-8). Three untreated patients had a rapid, lethal clinical course within 7 months after diagnosis; while, the remaining three achieved complete remission after treatment and were alive at the last follow-up. We suggest immune evasion-related extranodal large B-cell lymphoma should be recognized beyond the currently identified entities of IVLBCL and de novo CD5+ DLBCL.