临床特征和结局之间的差异，在病理学上定义的间质性淋巴瘤1-2级（FL1-2）和FL3a之间，仍不清楚，导致不确定如何治疗FL3a。然而，区分3a级和1-2级可能对于临床医生来说至关重要，以预测预后并因此做出治疗决策。我们比较了自2000年1月至2020年12月在中国全国15个中心诊断的1403名FL1-2患者和765名FL3a患者的临床特征和结局差异。与FL1-2患者相比，FL3a亚组有更高比例的老年患者（P=0.003），相对较多FL3a患者表现出LDH水平升高（P<0.0001）和Ki-67指数大于30%（P<0.001）。更多的FL3a患者接受了CHOP±R（P<0.0001）治疗，较少的患者接受了观察等待治疗方案（P<0.0001）。结果显示FL3a患者复发率较高，其中更多的患者在与FL1-2相比经历了组织学转化（HT）（P=0.003）。整个队列中1470（76.2%）名患者接受了R-CHOP疗法；生存分析显示FL3a患者的无进展生存率（PFS）比FL1-2患者更差。关于FLIPI的FL3a患者的生存分析显示，在中危和高危组中，PFS不佳，比FL1-2患者更差。FL3a患者的预后比FL1-2患者差得多，无论是否在24个月内进展病情（POD24）。FL3a患者患淋巴瘤相关死亡的可能性更高（LRD，P<0.05），而非LRD的比率是可比的。总之，本研究证明了FL3a患者的临床特征和结局与FL1-2患者有显著差异。结果突出了治疗FL3a患者时应采用不同于FL1-2的治疗方法。©2023作者。

The difference between clinical characteristics and outcomes between follicular lymphoma grade 1-2 (FL1-2) and FL3a defined pathologically remains unclear, resulting in uncertainty how to treat FL3a. However, it may be crucial for clinicians to discriminate grade 3a and grade 1-2 for predicting prognosis and thus making treatment decisions.We compared 1403 patients with FL1-2 and 765 patients with FL3a diagnosed between January 2000 and December 2020 from fifteen centers nationwide in China to describe differences in clinical characteristics and outcomes.Compared with FL1-2 patients, FL3a subgroup had a higher percentage of elderly patients (P = 0.003), and relatively more FL3a patients presented with increased levels of LDH (P < 0.0001) and higher Ki-67 indexs greater than 30% (P < 0.001). More FL3a patients were treated with CHOP ± R (P < 0.0001), and fewer were treated with the watchful-waiting approach (P < 0.0001). The results showed a higher incidence of relapse among FL3a patients, in which more patients underwent histological transformation (HT) when compared to FL1-2 (P = 0.003). 1470 (76.2%) patients of the entire cohort received R-CHOP therapy; survival analysis revealed that FL3a patients had a worse progression-free survival (PFS) rate than FL1-2 patients. Survival of FL3a patients with respect to FLIPI showed an inferior PFS in the intermediate and high-risk groups than FL1-2 patients. FL3a patients had a much worse prognosis than FL1-2 with or without progression of disease within 24 months (POD24). FL3a patients had higher likelihood of lymphoma-related death (LRD, P < 0.05), whereas the rates for non-LRD were comparable.In conclusion, this study demonstrates a marked difference in clinical features and outcomes in FL3a patients compared with FL1-2 patients. The results highlight the need for applying therapeutic approaches distinct from FL1-2 when treating FL3a patients.© 2023. The Author(s).