MYC/BCL2/BCL6 triple hit lymphoma: A study of 33 patients who had an aggressive clinical course similar to patients with double hit lymphomas.

Abstract

7559 Background: Large B cell lymphomas with MYC, BCL2, and BCL6 rearrangements, designated as triple hit lymphoma (THL), are uncommon. Large series studies of THL are scant and studies comparing THL to different types of double hit lymphoma (DHL) are lacking. Methods: We studied the clinicopathologic features and prognosis of 33 patients with THL and compared them to 83 patients with MYC/BCL2 DHL and 13 patients with MYC/BCL6DHL. Results: There were 21 men and 12 women, with a median age of 63 years (range, 34-85). Six patients had a history of low-grade B cell lymphoma and 27 had de novo lymphoma. These tumors were classified histologically as: 21 DLBCL, 10 high grade B-cell lymphoma, one concurrent DLBCL and follicular lymphoma (FL), and one concurrent DLBCL and mantle cell lymphoma. Immunohistochemical analysis showed that these tumors were positive for CD10 (94%), BCL6 (80%), BCL2 (93%), and MYC (69%, 40% as cutoff). 62% of tumors (8/13) with available data showed coexpression of MYC and BCL2. Using the Hans algorithm, 30 of 33 (91%) tumors had a germinal center B cell like (GCB) immunophenotype. All 7 cases tested by conventional cytogenetics showed a complex karyotype. Although BCL2 was always translocated with IGH, BCL6 translocated to MYC in 2of 7 cases of THL. Twenty-nine patients had treatment information available and all received immune-chemotherapy induction, including 11 with R-CHOP, 14 with R-EPOCH, 3 with R-HyperCVAD, and one with RICE (patient had a history of FL). The clinicopathological features of THL including induction chemotherapy were very similar to both the MYC/BCL2 DHL and MYC/BCL6 DHL (all P>0.05). There was no significant difference in median overall survival (OS) between patients with de novo lymphoma and those with a history of low-grade lymphoma (P=0.99). The OS in THL patients was 17.9 months, similar to the OS (17.2 months) of patients with MYC/BCL6 DHL and those with MYC/BCL2DHL (19.9 months) (P=0.60). Conclusions: MYC/BCL2/BCL6 THL is an aggressive B cell lymphoma and >90% of cases have a GCB immunophenotype. THL patients usually have an aggressive clinical course and a poor prognosis, similar to patients with double hit lymphomas.