CLinicopathological characteristics of extranodal marginal zone B‐cell lymphoma of the intestine: a single center analysis

Extranodal marginal zone B-cell lymphoma of the mucosa associated lymphoid tissue (MALT-lymphoma) is mot commonly diagnosed in the stomach (30%–35%), but is exceedingly rare in the intestinal tract (2%). Consequently, data on this special subgroup are scarce. Out of 484 patients with MALt-lymphoma diagnosed and treated at our institution from 1999 to 2020, 42 (11%) had intestinal involvement (24 primary and 18 secondary) and were restrospectively analyzed. Out of 18 patients rated as secondary intestinal invlevement, 14 patients had gastric MALT-lymphoma as the primary origin. Median age at diagnosis was 67 years (interquartile range (IQR) 53–72) and the median follow-up time was 47 months (IQR 32–102). Patients presenting with lymphoma-associated symptoms were significantly more common in the group of primary versus secondary intestinal MALT lymphomas (52% vs. 20%, p = .047). Nine patients each, i.e. 9/18 secondary and 9/24 primary intestinal MALT lymphomas were found positive for Helicobacter pylori. Intestinal organs involved included the colon (n = 19), duodenum (n = 11), small intestine (n = 8) and rectum (n = 5). MALT-IPI could be calculated for 39 patients, with low MALT-IPI documented in 37/39 cases. Seven patients were found to be positive for translocation t(11;18)(q21;q21), 6 of whom had primary gastric MALT lymphoma, suggesting the presence of the translocation as highly suggestive for secondary involvement. Treatment data were available in 41 our of those 42 patients. Eleven patients (27%) received local therapy (ten surgery, and one radiotherapy, complete response rate 90%), 16 (38%) systemic therapy (overall response rate 87%) and 9 (22%) had only antibiotic therapy (complete response rate 38%). in 4/41 patients, only watchfuil waiting was applied. Eighteen patients progressed during follow-up; the median progression free survival following first line therapy was 50 mos (CI: 38.4–53.7 mos), with anumerical trend towards longer PFS in primary (134 mos) versus secondary MALT lmyphoma (35.5 mos). The estimated overall survival was 301 months, with 6 patients having died during follow up (two from lymphoma progression, the other 4 from unrelated conditions). A comparison in terms of PFS and Os with the cohort of 144 patients with gastric MALT-lmyphoma showed no significant difference in terms of outcome. Overall, patients with intestinal MALT-lymphoma appear to have a good prognosis irrespcetive of primary or secondary involvement, whichbappears to be comparable to our data obtined in gastric MALT-lymphoma. Keyword: Extranodal non-Hodgkin lymphoma No conflicts of interests pertinent to the abstract.