BackgroundMultiple lymphomatous polyposis is a rare type of gastrointestinal lymphoma that extensively infiltrates the intestine. Multiple lymphomatous polyposis originates from the mantle zone of the lymphoma follicle and is considered to be a mantle cell lymphoma, which is a relatively aggressive type of B-cell non-Hodgkin’s lymphoma. We report an unusual case of a patient with multiple lymphomatous polyposis with extensive colorectal involvement and acute intestinal obstruction, an atypical complication of this rare disease. On the basis of this case study, the pitfalls in gastrointestinal tract lymphomatous polyposis diagnosis and prognosis, as well as the treatment options, are discussed.Case presentationOur patient was a 76-year-old white woman with asthenia, cramps, and swelling in the lower left quadrant of the abdomen, as well as weight loss within the previous 5 months. A colonoscopy revealed polyps in the rectum, sigmoid colon, descending colon, and right and left colic flexures. A biopsy revealed lymphomatous infiltration of the intestinal wall. Because of the large size of the polypoid masses, which narrowed the colonic lumen in multiple locations, the patient developed acute intestinal obstruction and was referred for laparotomy. She underwent a total proctocolectomy with a permanent ileostomy and a left salpingo-oophorectomy. Microscopic examination showed the presence of a multicentric, low-grade, small lymphocytic lymphoma. Immunohistochemical analysis revealed positive immunostaining for CD79a, CD20, and CD45. These results were consistent with the diagnosis of mantle cell lymphoma. Two weeks after surgery and prior to discharge, but before the beginning of chemotherapy, the patient’s general condition worsened as she experienced a severe and progressive respiratory tract infection, advanced respiratory insufficiency, and septic shock, and she ultimately died.ConclusionsMantle cell lymphoma develops as a progressive and aggressive disease with widespread polyposis of the gastrointestinal tract. The intensive chemotherapeutic regimens usually result in the regression of macroscopic and microscopic lesions; however, remissions are short in duration, and the median length of patient survival is 3–4 years. Mantle cell lymphoma is a rare disease that should be part of the differential diagnosis of polypoid diseases of the large intestine.