S6065 Watching and Waiting: A Call for Surveillance Guidelines in Duodenal-Type Follicular Lymphoma

Introduction: Duodenal-type follicular lymphoma (D-FL), a distinct variant of follicular lymphoma (FL), is typically discovered incidentally in the second portion of the duodenum on an esophagogastroduodenoscopy (EGD) performed for unrelated symptoms. D-FL is typically diagnosed at an early stage after immunostaining and follows an indolent course with favorable prognosis. Thus, observation is typically favored over chemoimmunotherapy. However, in rare cases, histological transformation arises without gross endoscopic change, and progresses in an aggressive, treatment-refractory course. Despite this, there are currently no established surveillance guidelines for D-FL – a clinical dilemma highlighted in this case. Case Description/Methods: A 55-year-old man with a history of autosomal dominant polycystic kidney disease underwent an EGD for new-onset nausea and vomiting. A 5 mm mucosal nodule was discovered and biopsied in the second portion of the duodenum. Histopathology demonstrated follicular and interfollicular involvement of the duodenal mucosa by an atypical lymphoid cell population comprised of small mature lymphoid cells with rare and scattered centroblasts. Overall, the findings were consistent with D-FL without high-grade transformation. The patient was referred to oncology. A positron emission tomography (PET) demonstrated focal metabolic activity in the second portion of the duodenum, along with multiple metabolically active mesenteric lymph nodes. Given the absence of B-symptoms and low disease, observation was favored. A repeat EGD 1 year later revealed similar findings, with biopsy consistent once more for D-FL without high-grade transformation. An observation strategy was maintained. Discussion: While most cases of D-FL exhibit benign behavior, histopathologic transformation is treatment-resistant and protrudes high mortality. There is currently a paucity of evidence regarding the optimal surveillance strategy in patients who do not exhibit systemic symptoms. Uncertainty is further compounded when imaging reveals metabolic activity, as seen here with PET-avid uptake in the second portion of the duodenum. Without appropriate guidance, it is uncertain to determine the interval and modality of surveillance, whether through repeat imaging, biopsy, or both. This case serves to demonstrate, and call for, defined surveillance protocols in D-FL.