Clinical Case Summary

Duodenal-Type Follicular Lymphoma (DTFL) is a rare form of non-Hodgkin’s lymphoma, accounting for <4% of gastrointestinal lymphomas. Though generally indolent, misdiagnosis can lead to delayed diagnosis in progressive cases. We present a case highlighting the importance of awareness for early detection. A 53-year-old woman with persistent epigastralgia underwent esophagogastroduodenoscopy (EGD) three times over five years at different hospitals. Only the latest EGD revealed multiple whitish nodular lesions in the first portion of the duodenum. Biopsies showed follicular proliferation confined to the mucosa, composed of small cleaved lymphoid cells. Immunohistochemistry confirmed a B-cell phenotype (CD20+, CD79a+, CD3-, CD5-), a germinal center phenotype (CD10+, Bcl6+), Bcl2 expression and low Ki-67. Blood tests were unremarkable, and viral serology was negative. CT scans revealed only reactive submandibular lymph nodes, with a normal bone marrow biopsy. PET scan showed uptake limited to the duodenum, confirming stage I disease (Lugano classification). Given its indolent course, a watch-and-wait strategy was adopted, with stable findings at a six-month follow-up EGD. DTFL is often incidentally detected during endoscopy and can be mistaken for benign conditions. Although typically localized, it may spread beyond the duodenum. Awareness is crucial to avoid unnecessary interventions and ensure timely diagnosis. Immunohistochemistry is key to distinguishing DTFL from reactive lymphoid hyperplasia and other low-grade lymphomas. While treatment options vary, active surveillance remains the most common approach due to its favorable prognosis. This case highlights DTFL as a rare but clinically significant entity that is frequently misdiagnosed, leading to unnecessary procedures. Recognizing its endoscopic and histologic features is essential for early diagnosis and appropriate management.

References

Figure 1: Upper endoscopy shows nodularity with whitish spots in the second portion of the duodenum (D2)
Figure 2: Endoscopic view showing a whitish polypoid lesion approximately 3 cm from the papilla
Figure 3: Duodenal mucosa with nodular lymphoid infiltrate, suggestive of duodenal-type follicular lymphoma

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