Background: Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL). Classification of DLBCL is often based on the cell of origin (COO), distinguishing between germinal center B-cell (GCB) and non-GCB subtypes. Although not yet recognized as a distinct entity by the World Health Organization (WHO), double expressor lymphoma (DEL), characterized by the co-expression of c-MYC and BCL2, carries an unfavorable prognosis for a subgroup of DLBCL patients. Another entity is the so-called high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements (double-hit/triple-hit lymphomas) diagnosed through fluorescent in-situ hybridization (FISH) analysis. Objective: This study aimed to determine the clinicopathologic profile and survival outcomes of Filipino DLBCL patients at the Philippine General Hospital (2016-2021), comparing double-hit versus non-double-hit and doubleexpressor versus non-double-expressor lymphomas, and assessing concordance between FISH-measured double-hit and IHC-measured double-expressor statuses. Methods: This is a single-arm, retrospective cohort study involving all surgical pathology cases signed out, with the aid of immunohistochemistry (IHC) studies, as NHL DLBCL, GCB, or non-GCB subtype, from 2016 to 2021. A second panel of IHC studies and FISH analysis using tissue microarray was subsequently done. Most cases exhibited a nonGCB subtype and were classified as DEL on second IHC panel. Five out of eleven DEL cases were reclassified as double hit lymphoma (DHL). Results: Clinically, most patients with these lymphomas present at age 60 years and below, exhibit B symptoms, with elevated serum lactate dehydrogenase (LDH) levels, at least stage III-IV disease at diagnosis, and possess a high International Prognostic Index (IPI) score, collectively indicating a poor prognosis. Conclusion Survival outcomes for patients with DLBCL ranges from three to 37 months. All cases of mortality were associated with DEL, contrasting with DHL cases which had variable outcomes. Due to limited sampling, statistical significance of the results cannot be determined. A comprehensive evaluation is essential to the diagnosis of DLBCL and DHL to include a complete immunohistochemistry panel and molecular testing, notably with FISH studies.
lymphoma ; lymphoma, large B-cell, diffuse ; cytogenetics ; immunohistochemistry