Clinicopathological Characteristics of Extranodal Marginal Zone Lymphoma of the Mucosa Associated Lymphoid Tissue (MALT-Lymphoma) of the Intestine: A Single Center Analysis.

Extranodal marginal zone B-cell lymphoma of the mucosa associated lymphoid tissue (MALT-lymphoma) is an indolent B-cell lymphoma with a distinct affinity for mucosal structures. Most commonly arising in the stomach, only roughly 2% of MALT-lymphomas occur in the colon or the intestine. In view of this, we have retrospectively assessed all patients with MALT-lymphoma involving the intestine for clinicopathological characteristics. Data of all patients with MALT-lymphoma and intestinal involvement (i.e. both primary and secondary), treated and followed at the Medical University of Vienna between 1999 and 2021 were retrospectively collected from hospital records and analyzed. Differences in baseline and therapy characteristics, as well as survival between primary and secondary, and between intestinal and gastric MALT-lymphoma (as the most common subgroup of patients) were investigated. In total, 42 patients were identified; 24/484 (5%) were classified as primary and 18 (3.7%) as secondary intestinal MALT-lymphomas. The most common primary intestinal location was the colon (10/24) and the most frequent primary site in the 18 cases with secondary intestinal MALT-lymphomas was the stomach (14/18). A total of 28/42 (66.7%) patients presented with LUGANO stage I, 7/42 (16.7%) with stage II/IIE and 7/42 (16.7%) with stage IV disease. Translocation t (11; 18) (q21; q21) was positive in 47% of patients with secondary and 25% of primary intestinal MALT-lymphomas. Median OS in for intestinal MALT-lymphoma was 301 months (95% CI n.a.) with 89.1% alive at 5 years and 77.2% alive at 10 years. Median PFS in the entire cohort was 50.4 months (95% CI 38.4-62.4 months), with an overall response rate and disease control rate of 73% and 97.3%, respectively. No difference in OS and PFS between primary and secondary intestinal, as well as between intestinal and gastric MALT-lymphoma was detected. Our data suggest that dissemination within the GI tract does not seem to be an adverse prognostic feature and highlights the preferred use of the Lugano staging system in such patients, which also summarizes multiple lesions within the GI-tract as Stage I.