A duodenal follicular lymphoma associated with the lesion mimicking MALT lymphoma in terminal ileum and Bauhin valve

This is a case report of a 66-year-old woman who consulted us with a 1-week history of postprandial epigastric discomfort and dyspepsia. Upper and lower gastrointestinal endoscopy and double-balloon enteroscopy revealed lesions in three parts: a swelling with a shallow depression in the ampulla of Vater, flat and rough nodules in the jejunum, and a mixture of lymphoid polyposis and rough surface of follicular lymphoma of the terminal ileum and Bauhin valve. The histological, immunophenotypic, and molecular findings of the duodenal lesion confirmed the diagnosis of follicular lymphoma. We initially diagnosed the ileal lesion as MALT lymphoma immunohistochemically. However, Southern blot hybridization analysis for immunoglobulin heavy chain gene rearrangement showed identical monoclonal bands in both the duodenal and ileal lesions. The molecular cytogenetic studies were also positive for the 14;18 translocation in both lesions. Therefore, the true diagnosis of this ileal lesion should be a follicular lymphoma with marginal zone differentiation. Primary follicular lymphomas of gastrointestinal tract were suggested to have intermediate features between nodal follicular lymphoma and MALT lymphoma. This case is an important clue to prove the similarity of follicular lymphoma of gastrointestinal tract to MALT lymphoma and will be crucial in considering the therapeutic strategy.