Increased incidence of follicular lymphoma in the duodenum

The incidence of indolent lymphomas in the lymph nodes and extranodal regio ns is quite different. Follicular lymphoma (FL) is most common in the nodes , and it seems to be least common in the gastrointestinal (GI) tract, where mucosa-associated lymphoid tissue lymphoma arises most frequently. The aut hors report that the incidence of FL is unexpectedly high in the duodenum c ompared with other portions of the GI tract. FL was detected in only eight of 222 cases of GI lymphoma (3.6%). However. five cases of FL arose in the duodenum, which accounted for 38.5% of 13 duodenal lymphomas. Only in two p atients did FL arise in either the stomach or the colorectum, and in the re maining patients FL was widespread with lymphomatous polyposis. Duodenal FL was composed of neoplastic follicles with small cleaved cells in dominance , and the immunophenotype of the lymphoma cells was CD10+, BCL-2+, CD20+, C D75+, CD79+, CD3-, CD5-, cyclin D1-, CD23-, and CD45RO-. All the patients w ere women age 37 to 66 years (average age, 52.4 yrs). Tn all patients the l ymphoma was present around the ampulla of Vater, and four of five patients showed multiple small-size polyps. Although lymphoma cell infiltration was confined to the submucosa in the four patients examined, the regional lymph nodes were involved partially in two patients without distant metastasis. All patients are alive at to 50 months of follow up (average, 27 mos), whic h is com parable with the prognosis for indolent nodal lymphomas. The-se re sults suggest that the duodenum has a distinct background of histogenesis o f the lymphomas and that biopsy specimens from the duodenum with multiple p olyps should be examined carefully.