BCL2 expression is associated with a poor prognosis independent of cellular origin in primary central nervous system diffuse large B-cell lymphoma

Keishi Makino, Hideo Nakamura, Naoki Shinojima, Jun-ichiro Kuroda, Shigetoshi Yano, Yoshiki Mikami, Akitake Mukasa

Primary central nervous system diffuse large B-cell lymphoma (CNS-DLBCL) is a distinct clinicopathological entity with a poor prognosis. Concurrent MYC and BCL2 overexpression predicts inferior prognosis in systemic DLBCL, although their prognostic significance remains unclear in primary CNS-DLBCL. Pretreatment diagnostic biopsy samples were retrospectively evaluated for 79 patients with primary CNS-DLBCL who were treated between January 2001 and December 2017. Histological and immunohistochemical testing were performed to evaluate the patients' statuses for various markers, which were also evaluated for associations with survival outcomes. According to the Hans criteria, 26 patients (32.9%) had the germinal center B-cell subtype and 53 patients (67.1%) had the activated B-cell subtype. Forty-one cases (51.9%) were positive for MYC (expression of ≥ 40%), 33 cases (41.8%) were positive for BCL2 (expression of ≥ 70%), 22 patients (27.8%) were positive for both MYC and BCL2, and 27 patients (34.2%) were negative for both MYC and BCL2. There were no significant differences in survival between the germinal center and activated B-cell subtypes. Furthermore, MYC positivity was not associated with overall survival (p = 0.369) or progression-free survival (PFS) (p = 0.253). However, BCL2 positivity was significantly associated with poor overall survival (p = 0.039) and PFS (p = 0.036). Co-expression of MYC and BCL2 was not associated with survival. Our data suggest that evaluating BCL2 expression may help predict the prognosis in cases of primary CNS-DLBCL.