OBJECTIVETo study the histological features, diagnosis, differential diagnoses of aggressive B-cell lymphomas of the gastrointestinal tract and to correlate clinical prognosis with pathologic parameters and immunophenotypes with an emphasis on c-myc, Tcl-1 and CD38 expression and their values in predicting the status of c-myc gene translocation.

METHODSFifty-four cases of aggressive B-cell lymphomas of the gastrointestinal tract with complete clinical and pathologic data were retrospectively collected. The clinical data, histologic and immunohistochemical findings and follow-up results were analyzed. Predictive immunohistochemical stains including c-myc, Tcl-1 and CD38 were performed and ROC curve analysis was used to confirm the accuracy of these markers in predicting c-myc translocation.

RESULTSOf 54 cases, there were 33 males and 21 females with median age of 56 years. Histological types of lymphomas included 49 cases of DLBCL (11 cases of germinal central B cell like and 38 cases of activated B cell like by Hans classification), 4 cases of DLBCL/BL and 1 case of BL. Eleven of 54 patients died within 97 months, with median survival of 42 months. Histologically, full-thickness infiltration of the gastrointestinal tract by large atypical cells with evident phagocytosis of karyorrhexis by macrophages ("starry sky") were seen in 18/54 cases. The lymphoma cells were positive for CD20 (54/54), CD79a (54/54), CD43 (4/54), CD5 (7/54), bcl-2 (26/54), Tcl-1 (17/54) and CD38 (15/54), but all negative for CD3 and CD30. The proliferative index by Ki-67 ranged from 40% to 100%. The univariate survival analysis indicated that B symptoms, general performance, high LDH, high IPI, distant metastasis, high clinical stage and tumors with over 90% of cells positive for c-myc were negative predictors for the patient's survival. In addition, cases of DLBCL positive for CD5 had an unfavorable prognosis. Cox regression analysis showed c-myc translocation, distant metastasis and high LDH were independent predictors for unfavorable prognosis. ROC curve revealed the percentage of c-myc positivity predicted the presence of c-myc gene translocation, with 75% as the optimal threshold.

CONCLUSIONSAggressive B-cell lymphomas of the gastrointestinal tract with a prognosis influenced by variable clinicopathologic factors. DLBCL and DLBCL/BL may possess c-myc translocation and tend to be Burkitt-like or atypical Burkitt lymphoma. As independent prognostic indicator, c-myc expression may be used for selection of therapeutic regimens and prognostication. High percentage of tumor cells with c-myc positivity may be used to predict the presence of c-myc gene translocation.