MYC/BCL2/BCL6 triple-hit lymphoma that presented with a suprasellar tumor and meningeal dissemination: A case report

Analysis of primary central nervous system large B-cell lymphoma in the era of high-grade B-cell lymphoma: Detection of two cases with MYC and BCL6 rearrangements in a cohort of 12 cases

High-grade diffuse large B-cell lymphoma (HG-DLBCL) refers to DLBCL with MYC and BCL2 and/or BCL6 rearrangements (double-hit or triple-hit DLBCL) that exhibits poor prognosis. Double-expressor DLBCL (c-myc+/bcl-2+) has intermediate prognosis when compared to HG-DLBCL. Primary central nervous system lymphoma (PCNSL) has distinct pathophysiology (frequent non-germinal center-like subtype and double-expressor) and has worse prognosis than systemic DLBCL. By fluorescence in situ hybridization (FISH), 25-30% of PCNSLs harbor BCL6 abnormalities with rare alterations in MYC, BCL2, double-hit or triple-hit events. We describe the clinicopathologic features and status of MYC, BCL2 and BCL6 in 12 PCNSLs (7 women, 5 men; median age 63 years; range: 28-79). Six cases showed focal starry-sky pattern. Immunohistochemically, all (100%) were of non-germinal center-like subtype, and 8/10 (80%) cases were double-expressors. Ki-67 ranged from 70 to 100%. FISH was positive in 9/12 (75%) cases: 4 (33%) harbored a BCL6 rearrangement, 3 (25%) had a gain of BCL2, 2 (17%) cases each had a gain of BCL6 and gain of IGH, and gain of MYC and deletion of MYC were observed in 1 case each (8%). Two (16%) cases were MYC/BCL6 double-hit PCNSLs. No MYC/BCL2 or triple-hit cases were identified. Eleven (92%) patients received chemotherapy and one also received whole brain radiation. The median time of follow-up was 4.4 months (range, 0.3-40.3). Seven (58%) patients are alive, 4 (33%) have died, and 1 (8%) had no follow-up. Five alive patients are in remission, including one MYC/BCL6 double-hit PCNSL. Our results add two new cases of rare double-hit PCNSL to the literature.

MYC, BCL2, and BCL6 rearrangements in primary central nervous system lymphoma of large B cell type

Primary central nervous system lymphoma (PCNSL) is a rare specific subtype of non-Hodgkin lymphoma limited to the brain, leptomeninges, spinal cord, or eyes without any systemic presentation and relapse which mostly takes place in CNS. In more than 95% of patients, it is of diffuse large B cell lymphoma (DLBCL) type. Categorizing PCNSL to germinal center cell like or activated B cell like, as we usually do for DLBCL NOS, may not be applicable for predicting outcome. Possible prognostic significance of MYC, BCL2, and/or BCL6 rearrangements may be important given what we know about their impact in systemic DLBCL, but we have limited knowledge about the status of double or triple hit molecular changes in PCNSL. Here, we have investigated prevalence of these molecular alterations in PCNSL. Two independent tissue microarrays constructed from 78 formalin-fixed paraffin-embedded blocks of confirmed PCNSL were tested for rearrangement of MYC, BCL2, and BCL6 by interphase fluorescent in situ hybridization (FISH) using break apart dual color probes. BCL6 translocation was detected in 15 (12%) cases. Translocation involving MYC and BCL2 was identified in 3 cases (3.8%) and 1 case (1.3%) respectively. One double hit lymphoma was discovered with both MYC/BCL2 translocation (1.3%). To the best of our knowledge, few organized studies have been conducted for MYC, BCL2, and/or BCL6 rearrangement in PCNSL. This study is evaluating large number of PCNSL. Double or triple hit events which are rarely seen in PCNSL.