Multiparameter analysis for discreet differential diagnosis of mucosa-associated lymphoid tissue lymphoma in the intestine

Background: The diagnosis of mucosa-associated lymphoid tissue (MALT) lymphoma in the intestine is occasionally difficult from histological examination on small biopsy specimens obtained by endoscopy. This study focused on unusual cases of reactive lymphoproliferative disorders in the intestine in order to make a differential diagnosis of MALT lymphoma. Materials and Methods: Five patients were examined with regards to clinical symptoms, endoscopic findings and multiparameter analysis (the morphological examination using routine hematoxylin and eosin staining by light microscopy, immunophenotyping by flow cytometry (FCM), immunohistochemistry and genotyping of extracted DNA). Results: All cases showed an aggregation of lymphocytes and one case showed similar features to lymphoepithelial lesions. Analyses of FCM and genetic rearrangements denied the monoclonality in all cases. Consequently, we considered that all cases should be diagnosed as reactive lymphoid hyperplasia and inflammatory change. Conclusion: Multiparameter analysis is useful in making an exact diagnosis of MALT lymphoma and therefore contributes to prevent unnecessary overtreatment.