S6074 More Than a Cramp: Mantle Cell Lymphoma Presenting as Adult Intussusception

Introduction: Mantle cell lymphoma (MCL) is a type of Non-Hodgkin’s Lymphoma, compromising 7% of all lymphoid neoplasms. It primarily affects older males, presenting with B symptoms, fatigue and lymphadenopathy. Pathogenically, MCL is driven by t(11;14)(q13;32) chromosomal translocation leading to Cyclin D over expression and unchecked B-cell proliferation. While gastrointestinal (GI) involvement is common, primary small bowel MCL presenting as intussusception is exceedingly rare. We report a case of MCL involving the terminal ileum presenting as ileocecal intussusception on colonoscopy. To our knowledge, only 3 such cases have been previously described. Case Description/Methods: A 66-year-old woman with chronic abdominal pain previously felt to be functional in etiology with esophagogastroduodenoscopy (EGD), colonoscopy, computed tomography enterography, gastric emptying study, and abdominal US 3 years prior largely unrevealing aside from gastric intestinal metaplasia seen on EGD and a subcentimeter gallbladder polyp on ultrasound (US). Surveillance abdominal US showed 2 calculi in the distal common bile duct. She underwent elective endoscopic retrograde cholangiopancreatography with sphincterotomy and cholecystectomy. A year later, she presented with persistent pain, new cramping of the right lower quadrant, and a 15 lb unintentional weight loss. A repeat computed tomography abdomen and pelvis with intravenous contrast revealed an asymmetric mass-like wall thickening of the distal ileum, approximately 20 cm from the ileocecal valve. Balloon-assisted colonoscopy showed distal ileum prolapsing through the ileocecal valve into the cecum with nodular and ulcerated mucosa. Biopsies confirmed MCL, staining positive for cyclin D1. Bone marrow biopsy confirmed involvement, but TP53 mutation was negative. She initially chose active surveillance, but positron emission tomography-computed tomography 1 year later revealed progression, and she was started on R-CHOP chemotherapy. Discussion: This case highlights the need to evaluate GI symptoms particularly when the characteristics change or red flag symptoms like unintentional weight loss develop. GI involvement in MCL is associated with a more aggressive phenotype and can present as Multiple Lymphomatous Polyposis (MLP) or a solitary lesion. However, lesions may be subtle or missed endoscopically. Histologically, MCL features lymphoid cells with irregular nuclear contours and condensed chromatin. Unlike the classic MLP presentation, our case had a mass-like terminal ileal lesion which presented as intussusception- a rare finding in adults, that warrants evaluation for malignancy, including lymphoproliferative disorders.