[The incidence of high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements in diffuse large B-cell lymphoma].

Objective: To investigate the incidence of high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangement in Chinese diffuse large B-cell lymphoma (DLBCL) . Methods: From January 2013 to August 2020, 922 DLBCL cases were collected. C-MYC and BCL2 protein expression levels were analyzed by immunohistochemistry staining. Fluorescence in situ hybridization was used to detect the structural abnormalities of MYC, BCL2, and BCL6, including gene breaks and copy number changes. Results: MYC and BCL2 and/or BCL6 gene breaks were found in 29 out of 922 DLBCL cases (3.15%) , including 25 cases of double-hit lymphoma (DHL; 14 cases involving MYC and BCL2 rearrangements and 11 cases involving MYC and BCL6 rearrangements) and four cases involving MYC, BCL2, and BCL6 rearrangements, referring to triple-hit lymphoma. According to the threshold of C-MYC ≥40% and BCL2 ≥50%, 541 cases (58.68%) overexpressed C-MYC and BCL2 proteins, including 22 DHL cases. Moreover, according to the threshold of C-MYC ≥70% and BCL2 ≥50%, 52 cases (5.64%) overexpressed C-MYC and BCL2 proteins, including nine DHL cases. The P53 protein expression was detected by immunohistochemistry staining. The mutant P53 expression pattern was shown in 101 out of 709 cases (14.25%) , whereas 13 cases (1.83%) were negative, likely indicating P53 gene fragment deletion. Conclusion: The incidence of high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements was low in DLBCLs, and no significant correlation between gene abnormality and protein overexpression was shown. The correct diagnosis of DHL depends on molecular genetic detection.