Antigen Receptor Gene Rearrangements And Flow Cytometry Immunophenotyping In Primary Gastric Lymphoma

AIMTo study the diagnostic value of immunoglobulin heavy chain (IgH) and T-cell receptor y (TCR-y) gene monoclonal rearrangements and flow cytometry immunophenotyping in primary gastric lymphoma (PGL).METHODSA total of48patients with suspected PGL at our hospital were prospectively enrolled in this study from January2009to December2011. The patients were divided into three groups (a PGL group, a gastric linitis plastica group, and a benign gastric ulcer group) based on the pathological results (gastric mucosal specimens obtained by endoscopy or surgery) and follow-up. Endoscopic ultrasonography (EUS) and EUS-guided biopsy were performed in all the patients. The tissue specimens were used for histopathological examination and for IgH and TCR-y gene rearrangement polymerase chain reaction (PCR) analyses and for flow cytometry immunophenotyping.RESULTSEUS and EUS-guided biopsy were successfully performed in all48patients. In the PGL group (n=21), monoclonal IgH gene rearrangements were detected in14(66.7%) patients. A positive result for each set of primers was found in12(57.1%),8(38.1%), and4(19.0%) cases using FR1/JH, FR2/JH, and FR3/JH primers, respectively. Overall,12(75%) patients with mucosal-associated lymphoid tissue (MALT) lymphoma (n=16) and2(40%) patients with diffuse large B-cell lymphoma (DLBCL)(n=5) were positive for monoclonal IgH gene rearrangements. No patients in the gastric linitis plastica group (n=17) and only one (10%) patient in the benign gastric ulcer group (n=10) were positive for a monoclonal IgH gene rearrangement. No TCR-y gene monoclonal rearrangements were detected. The sensitivity of monoclonal IgH gene rearrangements was66.7%for a PGL diagnosis, and the specificity was96.4%. In the PGL group,8(100%) patients with stage HE PGL (n=8) and6(46.1%) patients with stage IE PGL (n=13) were positive for monoclonal IgH gene rearrangements. The light chain expression was observed in the specimens from7of the21PGL patients using FCM; the specimens from6of the21PGL patients were assessed to include clonal B-cells, according to the previously published criteria. No light chain expression and clonal B-cells was detected in gastric linitis plastic group and benign gastric ulcer group. Of the7patients, the specimens from four patients were dominant for kappa light chain expression and those from three patients were dominant for lambda light chain expression.CONCLUSIONIgH gene rearrangements may be associated with PGL staging and may be useful for the diagnosis of PGL and for differentiating between PGL and gastric linitis plastica. FCI is helpful of making a diagnosis of PGL and also help to differentiate PGL from gastric linitis plastica and benign gastric ulcer. The sensitivity of FCI was61.9%for a PGL diagnosis, and the specificity was100%.