PD-L1 Expression in Uterine Mesenchymal Tumors: A Comparative Immunohistochemical Analysis

To evaluate and compare programmed cell death-ligand 1 (PD-L1) expression across benign and malignant uterine mesenchymal tumors using immunohistochemical analysis.

This retrospective study included 100 patients who underwent hysterectomy for uterine mesenchymal tumors at a single tertiary center between 2000 and 2022. Cases included leiomyoma (LM; n = 20), leiomyosarcoma (LMS; n = 20), low-grade endometrial stromal sarcoma (LG-ESS; n = 20), high-grade endometrial stromal sarcoma (HG-ESS; n = 20), and endometrial stromal nodule (ESN; n = 20). Immunohistochemical staining was performed using the PD-L1 (22C3) antibody, and PD-L1 expression was evaluated using the combined positive score. Clinicopathological parameters and PD-L1 expression were compared among tumor subtypes.

Patients with HG-ESS demonstrated a significantly higher mean age at diagnosis compared with the other histopathological subtypes. PD-L1 expression was detected in 9 (45%) LMS, 10 (50%) HG-ESS, 3 (15%) LG-ESS, and 1 (5%) ESN cases, whereas no LM cases demonstrated positivity. PD-L1 expression rates were significantly higher in LMS and HG-ESS than in LM, LG-ESS, and ESN cases (p < 0.0001). Combined group analyses also demonstrated significantly higher PD-L1 expression rates in the combined LMS/HG-ESS group compared with the LG-ESS group and the combined LM/ESN group (p < 0.0001).

These findings demonstrate increased PD-L1 expression in aggressive uterine mesenchymal tumors; however, the clinical and therapeutic significance of these immunohistochemical findings remains unclear. Further studies integrating PD-L1 expression with clinical findings and treatment outcomes are needed to determine the potential therapeutic relevance of PD-L1 in these neoplasms.