Lymphomatous polyposis of the gastrointestinal tract, including mantle cell lymphoma, follicular lymphoma and mucosa‐associated lymphoid tissue lymphoma

Aims: Lymphomatous polyposis (LP) is considered to represent mantle cell lymphoma (MCL) of the gastrointestinal (GI) tract. However, a few reports have suggested that some are follicular lymphoma (FL) or mucosa‐associated lymphoid tissue (MALT) lymphomas. In this study, we analysed 35 patients and clarified the clinicopathological features of LP. Methods and results: Paraffin‐embedded tissue samples were stained immunohistochemically and analysed by tissue‐fluorescence in situ hybridization (T‐FISH) for IGH/CCND1 (cyclin D1) and IGH/BCL2. The average age of the patients was 58.3 years. Over half of the cases showed gastric, duodenal, small intestinal, ileocaecal and sigmoid colonic lesions (15, 19, 15, 16 and 16 cases, respectively). Phenotypically, cases were classified into three types of MCL (cyclin D1+ CD5+ CD10–) ( n = 12), FL (cyclin D1– CD5– CD10+) ( n = 14) and MALT (cyclin D1– CD5– CD10–) ( n = 9). T‐FISH identified 11 of the 11 examined cases with MCLs to have IGH/CCND1, while seven of 10 cases with FL had IGH/BCL2, and none of the MALT cases were positive for IGH/CCND1 or IGH/BCL2. At the study endpoint, five of 12 patients with MCL were dead, two of 14 with FL and one of nine with MALT were dead of other disease. Event‐free survival analysis showed significantly poorest outcome in MCL, followed by FL, while MALT was associated with a favourable outcome ( P = 0.0040). Conclusions: Our study emphasizes the importance of differentiating MCL, FL and MALT of LP in evaluating prognosis and hence the most suitable therapeutic regimen.