PurposeTo analyze the clinical and pathological characteristics, treatment, and prognosis of high-grade B-cell lymphomas, not otherwise specified (HGBL, NOS), and to increase awareness of this type of lymphoma.Patients and MethodsWe collected clinical and pathological data of 41 cases of newly diagnosed HGBL, NOS, and analyzed diagnosis, prognosis and treatment to examine progression-free survival (PFS) and overall survival (OS).ResultsAmong the 41 cases studied, the median PFS was 6.0 months and the median OS was 18.0 months. Compared with patients treated with the R-CHOP regimen, patients treated with a high-intensity chemotherapy (DA-EPOCH-R, R-CODOX-M/IVAC, or R-Hyper-CVAD) had superior PFS and OS (PFS: χ2=4.173, P=0.041; OS: χ2=5.200, P=0.023). A subgroup analysis showed that the OS for the double-expressor lymphoma (DEL) was inferior to that for the non-DEL (χ2=4.563, P=0.033), and this trend was also seen for the single-hit lymphoma with MYC rearrangement (SHL) and the non-SHL (χ2=4.955, P=0.026). Patients with low International Prognostic Index (IPI) scores (≤2) had better survival rates than those with high scores (>2) (PFS: χ2=6.482, P=0.011; OS: χ2=10.156, P=0.001).ConclusionHGBL, NOS is associated with a high degree of malignancy, short survival period, and substantial extranodal involvement. High-intensity chemotherapy may improve patient prognosis. While IPI scores statistically correlated with the prognosis, SHL and DEL correlated with an inferior survival rate. New and improved treatments will be needed for HGBL, NOS.