Primary gastric mantle cell lymphoma in a patient with long standing history of Crohn's disease.

The stomach is the most common site of primary extranodal lymphoma. Virtually all cases are of B-cell lineage, including extranodal marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue (MALT lymphoma) and diffuse large B-cell lymphomas. While secondary gastric involvement from nodal mantle cell lymphoma (MCL) or in the course of primary intestinal MCL (lymphomatous polyposis) have been described, primary gastric MCL has not been reported so far. A 74-year-old man with a 14 year-history of Crohn's disease was admitted at a general hospital due to epigastric pain refractory to therapy with proton-pump inhibitors. Endoscopy disclosed a large polypoid tumor with an ulcerated surface at the greater curvature of the gastric antrum. Endosonography demonstrated the tumor to be limited to the stomach with only local lymph node involvement. Histology of gastric biopsies revealed a dense atypical lymphoid infiltrate composed of small to medium sized cells with slightly irregular nuclear contours. Immunohistochemichally, the cells were positive for CD20, CD79a, CD43 and cyclin D1, but negative for CD3, CD5 and bcl-6. They stained for IgM and showed lambda-light chain restriction. Fluorescent in situ hybridisation studies showed the presence of the t(11;14) characteristic for MCL. No further evidence of lymphoma was found on extensive clinical staging. Following chemotherapy the patient is disease free at 24 months after diagnosis. This is the first case of a primary localized gastric MCL. The lack of CD5 expression underscores the importance of performing thorough immunohistochemical studies, particularly to exclude MALT lymphoma.