Differentiation of follicular from mucosa-associated lymphoid tissue lymphoma by detection of t(14;18) on single-cell preparations and paraffin-embedded sections.

A 57-year-old woman was referred to the Kyoto Prefectural University of Medicine because of multiple polypoid lesions in the duodenum. On the basis of the histopathologic findings, mucosa-associated lymphoid tissue lymphoma had been diagnosed. The polypoid lesions did not show any improvement in spite of antimicrobial therapy for elimination of Helicobacter pylori. Because the disease remained stable during the clinical course, no other specific treatment was administered. We performed fluorescence in situ hybridization (FISH) analysis on a single-cell preparation obtained from the duodenal lesions, to assess the specific chromosome translocation. We identified BCL2/IGH fusion at a frequency of 83%. Two-color FISH was also performed on paraffin-embedded tissue sections, which demonstrated BCL2/IGH fusion-positive cells in neoplastic follicles. These findings, together with the CD10+ immunophenotyping of tumor cells, led to a diagnosis of primary follicular lymphoma of the duodenum. Interphase FISH with the IGH gene and oncogene probes is a rapid and powerful tool for assessing genomic changes in gastrointestinal lymphoma on single-cell preparations and tissue sections. This technique is particularly useful in view of the increasingly small core biopsy samples and needle aspirations obtained for diagnostic purposes.