S4541 Mantle Cell Lymphoma Diverted by Diverticulitis

Introduction: Hematochezia in a stable patient raises suspicion for bleeding from the lower gastrointestinal tract and warrants a broad differential diagnosis. We present a case of recurrent hematochezia and lower abdominal pain with imaging consistent with acute diverticulitis (AD) with no active extravasation, who was later diagnosed with mantle cell lymphoma (MCL). Case Description/Methods: A 76-year-old woman with diverticulosis presented with lower abdominal pain and rectal bleeding. Computed tomography (CT) abdomen and pelvis revealed sigmoid diverticulitis with mild periaortic, abdominopelvic, and groin adenopathy. CT angiogram (CTA) showed no active extravasation. Outpatient colonoscopy was arranged in 6 weeks, but the patient was lost to follow-up until symptom recurrence 1 year later, with imaging showing persistent sigmoid inflammation and progression of lymphadenopathy. Six weeks after discharge, outpatient colonoscopy found a cecal polyp, altered mucosal texture and vascularity which was further accentuated under narrow band imaging (NBI). Immunohistochemistry staining of the cecal polyp and mucosa revealed stage IV mantle cell lymphoma. Discussion: Diverticular disease causes 20%-50% of lower gastrointestinal bleeds (LGIB). Other causes include hemorrhoids, vascular malformations and neoplasms. Colonoscopy is useful in identifying the source LGIB but is contraindicated in AD due to perforation risk. In patients with hematochezia in the setting of AD, CTA is utilized to locate active bleeding enabling embolization. However, false negatives occur if there is no active bleeding at time of scan. Regardless of CTA results, AGA guidelines recommend colorectal cancer screening via colonoscopy 4-6 weeks after resolution of AD. Our patient underwent colonoscopy 1 year after initial episode of hematochezia. At time of colonoscopy, imaging showed progression of nonspecific abdominopelvic lymphadenopathy, supporting her diagnosis of stage IV MCL. There is recent push toward abandoning post-AD endoscopic evaluation. This case reemphasizes the importance of adhering to current AGA recommendations of colonoscopy at 4 to 6 weeks post-AD to rule out malignancy, especially in the setting of alarm symptoms such as changes in stool caliber, iron deficiency anemia, abdominal pain, blood in stool, and weight changes. Additionally, this case highlights the clinical utility of NBI in evaluating subtle mucosal changes otherwise overlooked with conventional white-light endoscopy.