Primary gastrointestinal follicular lymphoma involving the duodenal second portion is a distinct entity: A multicenter, retrospective analysis in Japan

We conducted a multicenter, retrospective study to determine the anatomical distribution and prognostic factors of gastrointestinal (GI) follicular lymphoma (FL). This study included 125 patients with stage I and II1 GI–FL. Of the 125 patients, the small intestine was examined in 70 patients, with double‐balloon endoscopy and/or capsule endoscopy. The most frequently involved GI–FL site was the duodenal second portion (DSP) (81%), followed by the jejunum (40%); 85% of patients with involvement of the DSP also had jejunal or ileal lesions. The absence of abdominal symptoms and macroscopic appearance of multiple nodules were significantly present in the DSP‐positive group. During a median follow up of 40 months, six patients showed disease progression. Patients with involvement of the DSP had better progression‐free survival (PFS) than those without such involvement (P = 0.001). A multivariate analysis revealed that male sex, the presence of abdominal symptoms, and negative involvement of the DSP were independently associated with poor PFS. In conclusion, most patients with GI–FL have duodenal lesions associated with multiple jejunal or ileal lesions. Gastrointestinal follicular lymphomas involving the DSP might be a distinct entity showing a favorable clinical course. (Cancer Sci 2011; 102: 1532–1536)