[Primary gastrointestinal diffuse large B-cell lymphoma: an immunohistochemical and prognostic study of 90 cases]

To study the immunophenotype and prognostic significance of primary gastrointestinal diffuse large B-cell lymphoma, with reference to Hans, Choi and Tally algorithms.

The clinicopathologic features and follow-up data in 90 cases of primary gastrointestinal diffuse large B-cell lymphoma were analyzed by Kaplan-Meier method, Log-rank test and Cox regression model. Immunohistochemistry was carried out using EliVision and EnVision methods for CD20, CD3ε, CD10, bcl-6, MUM-1, CD5, bcl-2, GCET1, FOXP1, LMO2, BLIMP1 and Ki-67.

The age of patients ranged from 27 to 83 years (mean = 58 years). The male-to-female ratio was 1.31:1. Amongst the 90 cases studied, 64.4% (58/90) involved the stomach and 35.6% (32/90) involved the intestine. The immunohistochemical findings were as follows: 100% positivity for CD20, 0% for CD3ε and CD5, 17.8% (16/90) for CD10, 75.6% (68/90) for bcl-6, 52.2% (47/90) for MUM-1 (cut off was 30%), 43.3% (39/90) for MUM-1 (cut off was 80%), 50.0% (45/90) for GCET1, 45.6% (41/90) for FOXP1, 23.3% (21/90) for LMO2, 42.2% (38/90) for bcl-2 and 8.9% (8/90) for BLIMP1. The Ki-67 index ranged from 20% to 95% (median = 80%). According to Hans algorithm, 51.1% of the cases belonged to germinal center B-cell (GCB) subtype and 48.9% belonged to non-GCB subtype. In contrast, Choi algorithm classified 55.6% cases as GCB subtype and 44.4% as activated B-cell (ABC) subtype. According to Tally algorithm, 34.4% were of GCB subtype and 65.6% of non-GCB subtype. Most of the patients (67.8%, 61/90) received chemotherapy and 68.9% (62/90) underwent surgical resection. The overall 2, 3 and 5-year survival rates were 58.5%, 52.8% and 49.8%, respectively. The overall 2, 3 and 5-year survival rates in the CHOP therapy group were 68.5%, 61.2% and 52.9%, respectively.

There is no significant difference in ratio between the GCB and non-GCB/ABC subtypes by Hans and Choi algorithms. The non-GCB subtype seems to be more prevalent according to Tally algorithm. Although there is no significant difference in survival between GCB and non-GCB/ABC subtypes by the 3 algorithms, GCB subtype tends to show a better survival. In univariate analysis, LDH level, international prognostic index, chemotherapy, surgical resection, B symptoms, number of involved sites and clinical stage are found to have prognostic significance. In multivariate analysis, Choi algorithm, Tally algorithm, chemotherapy, surgical resection, LDH level and clinical stage are independent prognostic factors.