In our study, GI-DLBCL exhibited high-frequency mutations in B2M, CCND3, HIST1H1C, BIRC6, TET2, KMT2C, LRP1B, CSMD3, FAT4, RHOA, MUC4, and FBN2, revealing consistent mutation frequencies and variants in common with DLBCL in cBioPortal and COSMIC. Here, CSMD3 is linked to diffuse large B-cell lymphoma.