Triple-hit B-cell Lymphoma with MYC, BCL2, and BCL6 translocations/rearrangements: Clinicopathologic Features of 11 Cases

Lymphomas with translocations/rearrangements of MYC, BCL2, and BCL6, so-called triple-hit B-cell lymphoma, are rare, and few studies on these tumors are available in the literature. We report 11 cases of triple-hit B-cell lymphoma and characterize their clinicopathologic findings. All patients were men, with a median age of 64 years (range, 45 to 80 y), and 4 patients had antecedent or concurrent follicular lymphoma. Using the 2008 World Health Organization classification, these cases were classified as: 5 B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma; 4 DLBCL; 1 DLBCL with concurrent follicular lymphoma; and 1 low-grade follicular lymphoma. All cases were positive for CD10, BCL2, and FOXP1. Ten of 11 cases were positive for CD20. MYC expression was high in 10/11 (91%), BCL6 was positive in 8/11 (73%), and MUM1/IRF4 was positive in 6/11 (55%) cases. T-cell antigens, TdT, and Epstein-Barr virus-encoded RNA were negative in all cases. Ten of 11 cases showed a high proliferation index - 70% to 100%, and the follicular lymphoma had a 30% proliferation rate. Using most algorithms, all cases belonged to germinal center B-cell-like group. All patients received standard or more aggressive immunochemotherapy regimens. Three patients had no response to chemotherapy; 4 patients showed a partial response; 2 patients had complete remission after chemotherapy; and 2 patients had just begun chemotherapy. Three patients underwent a stem cell transplant. The median follow-up time was 5.3 months. Five patients died, and 6 patients were alive at last follow-up. Two patients who underwent stem cell transplant after complete response to chemotherapy were in remission with 16 to 19 months of clinical follow-up. In summary, triple-hit lymphomas are clinically aggressive tumors associated with a poor prognosis. Patients often respond poorly to chemotherapy, but a subset may completely respond to chemotherapy followed by stem cell transplant.