Background: Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma (NHL), characterized by clinical and molecular heterogeneity. Genetic alterations in signaling pathways, especially the MYD88 gene, have been implicated in disease progression and prognosis. Although MYD88 protein expression is frequently observed in the activated B-cell (non-GCB) subtype, its prevalence and prognostic significance in all DLBCL remain controversial.

Objective: To investigate the prevalence of MYD88 protein expression, its associated factors, and its prognostic role in patients with DLBCL.

Materials and Methods: This retrospective study analyzed eighty-six DLBCL tissue samples collected between January 1, 2014, and December 31, 2023. These samples were evaluated for MYD88 protein expression using immunohistochemistry (IHC) to determine the expression, associated factors, and impact on overall survival (OS).

Results: The prevalence of MYD88 protein expression in the present study was 87.2%, being highest in the non-GCB subtype (61.3%). The expression was significantly associated with advanced Ann Arbor stage (III-IV) (74.7%), high lactate dehydrogenase (LDH) levels (84%), high intermediate-risk NCCN-International Prognostic Index (IPI) (scores 4 to 5) (49.3%), and a high Ki-67 proliferation index ≥70% (74.7%). Significantly poor prognostic variables for OS included ECOG status ≥2 (p=0.03), advanced Ann Arbor stage (III-IV) (p=0.018), and high-risk NCCN-IPI (scores ≥6) (p=0.001), but not MYD88 protein expression (hazard ratio [HR] 1.07, p=0.869). Only a high serum LDH level was an independent risk factor (adjusted HR 8.324, p=0.042).

Conclusion: High prevalence of MYD88 protein expression was found in DLBCL, especially the non-GCB subtype. No significant association between MYD88 protein expression and OS in DLBCL patients.

Received 18 December 2025 | Revised 5 May 2026 | Accepted 8 May 2026

J Med Assoc Thai 2026;109(9):707-17

DOI: 10.35755/jmedassocthai.2026.9.03950