Primary large B-cell lymphoma of the central nervous system: A reappraisal of CD5-positive cases based on clinical, pathological, and molecular evaluation

• Published in: Pathology international 2024-12
• Main Authors: Yamada, Seiji, Satou, Akira, Tsuyuki, Yuta, Iba, Sachiko, Okumura, Yuka, Ishikawa, Eri, Ito, Hideaki, Kogure, Yasunori, Goto, Naoe, Tanikawa, Motoki, Shimada, Kazuyuki, Tsukamoto, Tetsuya, Karube, Kennosuke, Yokoo, Hideaki, Kataoka, Keisuke, Tomita, Akihiro, Mase, Mitsuhito, Nakamura, Shigeo
• Format: Article
• Language: English
• ISSN: 1440-1827; 1440-1827
• DOI: 10.1111/pin.13496

CD5 expression is seen in 5%-10% of de novo diffuse large B-cell lymphomas (DLBCLs). Primary large B-cell lymphoma of the central nervous system (PCNS-LBCL) also exhibits CD5 expression in a minority of cases, however, clinicopathological and molecular features remain largely unclarified. Here we present the clinical, molecular, and pathological features of 11 CD5-positive ( ) PCNS-LBCL cases, occupying 6.7% of all 165 PCNS-LBCLs diagnosed in our institutions. While CD5 systemic DLBCL has been recognized as a distinctive subgroup showing an aggressive clinical course, no obvious differences were found between CD5 and CD5-negative subgroups among the present CNS patients clinically. MYD88 p.L265P and CD79B p.Y196 mutations were detected in eight (73%) and seven (64%) cases, respectively, supporting previous reports. Notably, the microenvironmental immune cells were universally PD-L1/CD274-positive, and the higher levels tended to present favorable overall survival, as already evidenced in the PCNS-LBCL series. In contrast, neoplastic PD-L1/CD274 expression was undetectable in all cases. Indeed, no structural variations or copy number alterations involving PD-1 ligands were detected by targeted-capture sequencing and fluorescence in situ hybridization. While further studies are warranted, we may have confirmed similarity between PCNS-LBCLs and intravascular large B-cell lymphomas from a molecular standpoint.