Gizem TEOMAN, Elanur KARAMAN, Muhammet Salih AYAS, İsmail SAYGIN
Journal of Health Sciences and Medicine - 2026;9(4):977-981
Aims: Sarcomas are rare and heterogeneous mesenchymal malignancies with diverse histological and molecular characteristics. Programmed death-ligand 1 (PD-L1) plays a key role in tumor immune evasion and may serve as a predictive biomarker for immune checkpoint inhibitor therapy. This study aimed to characterize PD-L1 expression across different sarcoma subtypes. Methods: A total of 54 sarcoma cases diagnosed between January 2020 and September 2025 at the Department of Medical Pathology, Karadeniz Technical University, were retrospectively analyzed. Subtypes included undifferentiated pleomorphic sarcoma (UPS, n=10), liposarcoma (well-differentiated, dedifferentiated, myxoid; n=17), osteosarcoma (n=7), leiomyosarcoma (n=7), myxofibrosarcoma (n=8), and fibromyxoid sarcoma (n=5). PD-L1 expression was assessed immunohistochemically using the validated monoclonal antibody clone 22C3 and quantified by the combined positive score (CPS). PD-L1 positivity was defined as CPS >=1%. Results: Overall, 18 of 54 cases (33.3%) exhibited PD-L1 positivity. Expression varied across sarcoma subtypes, with relatively higher positivity rates observed in myxofibrosarcoma (4/8, 50%), leiomyosarcoma (3/7, 42.8%), osteosarcoma (3/7, 42.8%), and UPS (4/10, 25%). Lower PD-L1 expression was observed in fibromyxoid sarcoma (1/5, 20%) and liposarcoma (3/17, 17.6%). Among the liposarcoma subtypes, PD-L1 positivity was detected in one well-differentiated, one dedifferentiated, and one myxoid case. Conclusion: PD-L1 expression in sarcomas is heterogeneous and subtype-dependent. High-grade pleomorphic tumors, particularly myxofibrosarcomas, leiomyosarcomas, and osteosarcomas, appeared to demonstrate relatively more frequent PD-L1 positivity in this cohort. These findings provide insights into the immunobiology of sarcomas and support the potential rationale for future studies evaluating PD-1/PD-L1-targeted immunotherapies in PD-L1-expressing sarcoma subtypes.
