Follicular dendritic cell staining pattern as a prognostic marker for the watch-and-wait policy in patients with gastrointestinal follicular lymphoma.

BACKGROUND/AIMS: Gastrointestinal follicular lymphoma (GI-FL) patients with low tumor burden are often managed with a "watch and wait" (W&W) strategy, but regular endoscopic examinations impose a significant burden. We investigated whether the follicular dendritic cell (FDC) staining pattern of GI-FL lesions could help identify a lower-risk subgroup of patients during W&W follow-up. METHODS: We studied 76 Japanese patients with GI-FL (September 2003-July 2022), classified by CD21 staining into "duodenal pattern" (n=57) and "nodal pattern" (n=19) groups. All patients underwent regular clinical, endoscopic, and imaging follow-up. Progression-free survival (PFS), time to treatment required (TTR), and overall survival (OS) were compared between the two groups. RESULTS: Patients with a "duodenal pattern" had better outcomes than those with a "nodal pattern." In the "duodenal pattern" group, 25 of 57 patients (43.9%) progressed, but only 9 (15.8%) required treatment. In the "nodal pattern" group, 14 of 19 patients (73.7%) progressed and all required treatment; 8 (42.1%) developed local compressive symptoms necessitating immediate treatment, versus none in the "duodenal pattern" group. OS was excellent in both groups. CONCLUSION: The FDC staining pattern of the tumor is a useful marker for the management of patients with GI-FL. Patients with an FDC "duodenal pattern" have slower disease progression and rarely require treatment. These findings suggest that the "duodenal" FDC pattern may help identify candidates for future prospective studies of individualized or de-escalated surveillance, which could ultimately reduce the physical and financial burden of follow-up while maintaining good outcomes.