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A large single-institution retrospective analysis of aggressive B-cell lymphomas according to the 2016/2017 WHO classification.

BACKGROUND
High-grade B-cell lymphomas (HGBLs) comprise a new entity in the revised 2016/2017 World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues. The diagnosis of HGBL encompasses histopathology and immunohistochemistry, with additional molecular examination of the BCL2/MYC or BCL6/MYC rearrangement status.


OBJECTIVES
The aim of the study was to summarize our experience in the histopathological and immunohistochemical diagnosis of patients with aggressive B-cell lymphomas according to the revised 2016/2017 WHO classifications.


MATERIAL AND METHODS
We reviewed our single-institution experience with accurate diagnoses of HGBL and diffuse large B-cell lymphoma (DLBCL) using the available histopathological and immunohistochemical tools. The timeframe was from January 1, 2017 to April 18, 2018.


RESULTS
Out of 265 patients, 217 (81.9%) were diagnosed with DLBCL, 43 (16.2%) with HGBL/DLBCL and 5 (1.9%) with not otherwise specified HGBL (HGBL-NOS). Regarding concurrent expression of MYC and BCL2 and/or BCL6 (double expressors (DE) and triple expressors (TE)), more DE and TE cases were found in the HGBL/DLBCL group than in the DLBCL group (25.53% vs 8.47%, p < 0.001, for DE cases and 55.32% vs 6.21%, p < 0.001, for TE cases). All 48 (100.00%) of the HGBL-NOS and HGBL/DLBCL patients, and 26 (11.98%) of the DLBCL-DE/TE cases were recommended for molecular analysis.


CONCLUSIONS
Our findings show that a comprehensive histopathological and immunohistochemical examination may identify potential HGBL cases. This study emphasizes the need to introduce a suitable molecular examination for patients with HGBL morphology and/or double/triple expression of BCL2/BCL6/MYC proteins.