PD-L1 Immunoexpression in Selected Cases of Lung Carcinoma: A Retrospective Cross-Sectional Study from a Tertiary Care Center in Bangladesh

Abstract Background: Programmed death-ligand 1 (PD-L1) is an important predictive biomarker for immune checkpoint inhibitor therapy in non-small cell lung carcinoma (NSCLC). Immunohistochemical assessment of PD-L1 expression has become an essential component in selecting patients for immunotherapy. Objective: To evaluate PD-L1 immunoexpression in selected cases of lung carcinoma and determine its distribution among different histological subtypes. Methods: This retrospective cross-sectional study was conducted in the Department of Pathology, Bangladesh Medical University, from 1 June 2025 to 10 June 2026. Thirty-five histopathologically confirmed cases of lung carcinoma in which PD-L1 immunohistochemistry using the PD-L1 (22C3) monoclonal antibody clone had been performed were included. PD-L1 expression was assessed by Tumor Proportion Score (TPS). Data were analyzed using descriptive statistics. Results: The age of the patients ranged from 40 to 83 years, with a mean age of 60.8 ± 10.9 years. Among the 35 cases, 24 (68.6%) were male and 11 (31.4%) were female. Adenocarcinoma was the most common histological subtype (57.1%), followed by squamous cell carcinoma (34.3%), NSCLC-NOS (5.7%), and adenosquamous carcinoma (2.9%). PD-L1 positivity was observed in 4 (11.4%) cases. Among the positive cases, three were adenocarcinoma and one was NSCLC-NOS. TPS values were 29%, 30%, and 50% in adenocarcinoma cases and 15% in the NSCLC-NOS case. One adenocarcinoma demonstrated high PD-L1 expression (TPS ≥50%). Conclusion: PD-L1 expression was identified in a small proportion of selected lung carcinoma cases and was predominantly observed in adenocarcinoma. Routine PD-L1 testing may facilitate identification of patients who are likely to benefit from immune checkpoint inhibitor therapy.