The WHO recently changed the outline of immunodeficiency/dysregulation (IDD)-associated lymphoproliferative disorders (LPDs)/lymphomas from underlying IDD settings to an overarching framework and accommodates commonalities in histology, the involvement of various oncogenic viruses, and specific clinical/therapeutic consequences. A mutational analysis has been performed on post-transplantation and HIV-positive lymphomas, but not on other iatrogenic immunodeficiency (OII)-associated LPDs mainly caused by methotrexate (MTX) to treat rheumatoid arthritis. We herein conducted next-generation sequencing (NGS) to examine the genetic spectrum along with a fluorescence in situ hybridization analysis of 9p24.1 and PD-L1 expression in 37 MTX-associated diffuse large B-cell lymphoma (DLBCL) cases, 17 Epstein-Barr virus (EBV)-positive mucocutaneous ulcer (EBVMCU) cases, and 26 EBV-positive DLBCL (EBV + DLBCL) cases. Targeted NGS identified 177 mutations. The mutation frequency was significantly higher in EBV^- MTX-DLBCL than in EBV-positive LPDs/lymphomas (EBVMCU, EBV⁺ MTX-DLBCL, and EBV + DLBCL). Regrowth or resistance to spontaneous regression after MTX withdrawal was more likely in EBV^- MTX-DLBCL than in EBV⁺ MTX-DLBCL. Therefore, accumulated gene mutations, sustained by the restored immune status in EBV^- MTX-DLBCL, may affect clinical outcomes after MTX discontinuation. Several unique genetic findings were obtained for each category. Fewer TET2/DNMT3A and CD58 mutations in OII-LPD/lymphomas (EBVMCU and MTX-DLBCL) than in EBV + DLBCL indicate that clonal hematopoiesis and an immune evasion-related background contributed less to lymphomagenesis in OII-LPDs. MYD88^L265P/CD79B^Y196 mutations were only detected in EBV^- MTX-DLBCL. SOCS1 mutations were significantly more frequent in EBV-positive LPD/lymphoma categories, irrespective of the immune status, than in EBV^- MTX-DLBCL. These results reveal distinct genetic features among MTX-DLBCL (EBV+/-), EBVMCU, and EBV + DLBCL.

© 2025 The Author(s). Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

世界卫生组织（WHO）最近将免疫缺陷/失调（IDD）相关淋巴增生性疾病（LPDs）/淋巴瘤的分类从基于潜在IDD的情况改为一个总体框架，并容纳了病理学上的共性、多种致癌病毒的作用以及特定的临床和治疗后果。已对移植后和HIV阳性淋巴瘤进行了突变分析，但未针对主要由甲氨蝶呤（MTX）治疗类风湿关节炎引起的其他医源性免疫缺陷（OII）相关LPDs进行此类研究。我们在此通过下一代测序（NGS）来检测37例与MTX相关的弥漫大B细胞淋巴瘤（DLBCL）病例、17例EB病毒（EBV）阳性的黏膜皮肤溃疡（EBVMCU）病例以及26例EBV阳性DLBCL（EBV+ DLBCL）病例的基因谱，并进行9p24.1和PD-L1表达的荧光原位杂交分析。靶向NGS鉴定出177个突变。与EBV阳性的LPDs/淋巴瘤相比，EBV阴性MTX-DLBCL中的突变频率显著更高（包括EBVMCU、EBV阳性MTX-DLBCL和EBV+ DLBCL）。在停止使用甲氨蝶呤后，EBV阴性MTX-DLBCL重新生长或自发消退抵抗的情况比EBV阳性MTX-DLBCL更常见。因此，在停止使用甲氨蝶呤之后，累积的基因突变可能影响EBV阴性MTX-DLBCL患者的临床结果，这些突变在恢复后的免疫状态下得以维持。每个类别都获得了几个独特的遗传发现。与EBV+ DLBCL相比，OII-LPD/淋巴瘤（包括EBVMCU和MTX-DLBCL）中的TET2/DNMT3A和CD58突变较少，表明克隆造血作用和免疫逃逸相关背景在OII-LPD的淋巴瘤发生中贡献较小。MYD88L265P/CD79BY196突变仅出现在EBV阴性MTX-DLBCL中。无论免疫状态如何，在所有EBV阳性LPD/淋巴瘤类别中，SOCS1突变的发生频率显著高于在EBV阴性MTX-DLBCL中的发生频率。这些结果揭示了MTX-DLBCL（EBV+/–）、EBVMCU和EBV+ DLBCL之间的不同遗传特征。

© 2025 The Author(s). Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.