[Aggressive B-cell lymphomas of gastrointestinal tract: a clinicopathologic analysis of 54 cases].

Objective: To 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.

Methods: Fifty-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.

Results: Of 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.

Conclusions: Aggressive 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.