Introduction: Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma (NHL) and represents a clinically and biologically heterogeneous group of aggressive lymphoid malignancies. Despite advances in chemo-immunotherapy, relapse and refractory disease remain important challenges, particularly where access to advanced diagnostics and treatment modalities are limited.

Objective: To describe the clinicopathological characteristics, treatment modalities, and treatment outcomes of adult patients diagnosed with DLBCL at a tertiary care center in Nepal.

Methodology: This retrospective cohort study included adult patients diagnosed with DLBCL and treated at Vayodha Hospital between January 2018 and December 2023. Patients were followed until December 2025. Demographic characteristics, clinical presentation, disease distribution, staging and treatment modalities were reviewed from medical records. Treatment outcomes, including relapse and mortality, were analyzed. A total of 35 adult patients were included.

Results: The mean age at presentation was 45 years, with an age range of 21–76 years. The male-to-female ratio was 1.18:1. Sixteen patients (46%) were between 40 and 60 years of age. Twenty-five patients (71%) presented within 1–3 months of symptom onset. B symptoms were documented in 14% of patients. Nodal disease was present in 20 patients (57%), while 15 patients (43%) had extranodal disease. Extranodal sites included the gastrointestinal tract, tonsil, thyroid, spine and testis. Bulky disease was observed in 14% of patients, commonly involving the axilla and mediastinum. Contrast- enhanced computed tomography was used for staging and response assessment in 80% of patients, while positron emission tomography-computed tomography was used in 20%. Stage II disease constituted the largest group (71%), while 23% had advanced-stage disease. Cyclophosphamide, doxorubicin, vincristine and prednisolone (CHOP)-based therapy was administered to 18 patients (51%), whereas 17 patients (49%) received rituximab-based treatment. Eleven patients (31%) experienced relapse and four (11%) died from refractory or progressive disease. Thirty-one patients (88%) remained alive and were followed up. The mean duration of follow-up was 72.3 months (range 8–96 months).

Conclusion: In this Nepalese cohort, DLBCL commonly presented during the fifth decade of life, with nodal disease being more frequent than extranodal disease. Although the majority of patients received treatment, almost one-third experienced relapse. Financial limitations affecting access to advanced investigations and treatment may influence management. Relapsed DLBCL remains a significant therapeutic challenge, particularly where transplantation and other advanced treatment options are unavailable.