Mucosa-associated marginal zone B-cell lymphoma (MALT Lymphoma) of terminal ileum

Abstract

Extranodal mucosa-associated marginal zone B-cell lymphoma (MALT lymphoma) is extremely rare in ileum. A 35-year-old woman with traffic accident was found to have an ulcerated tumor (4 cm × 4 cm) in terminal ileum. Biopsies showed proliferation of atypical lymphocytes which were small or medium-sized, and resembled centrocytes. Germinal center-like nodular areas, plasma cell differentiation, and lymphoepithelial lesions (LELs) were seen. Immunohistochemically, the atypical lymphocytes showed high proliferative activity; the Ki-67 labeling was 82%. The atypical lymphocytes were positive for p53, vimentin CD45, CD20, CD79, CD30, CD10, λ-chain, κ-chain and bcl-2, but negative for cytokeratin (CK) AE1/3, CK CAM5.2, CD45RO, CD3, CD23, CD43, CD68, CD56, CD10, TdT, CD4, CD5, CD8, and cyclin D1. Plasma cell differentiation was positive for CD38, CD79α, and CD138. Light chain restriction was present. The germinal center-like areas were negative for bcl-2. Since only B-cell markers were positive and histological features suggested a low grade neoplasm, the tumor was indolent low-grade B-cell neoplasms including MALT lymphoma, mantle cell lymphoma, lymphoplasmacytic lymphoma, follicular lymphoma, small lymphocytic lymphoma/CLL. A differential diagnosis was performed and discussed, and final diagnosis was ileal MALT lymphoma. After diagnosis, extensive examinations including CT, MRI, PET, endoscopies were performed; they revealed no tumors other than the ileal tumor. The patient is now treated by chemotherapy and radiation. The prognosis seems good.