CD274 and ovarian serous carcinoma: In ovarian serous carcinoma, high PD-L1 expression in stromal tumor-infiltrating lymphocytes, tumor cells, and intraepithelial tumor-infiltrating lymphocytes was noted in 29 (20.7%), 13 (9.3%), and 19 (13.6%) patients of total 140 patients with ovarian serous carcinoma, respectively.