['Pulmonary pleomorphic carcinomas (PPCs) are uncommon malignant tumours characterised by an aggressive clinical course and poor survival. These neoplasms frequently exhibit marked confluent necrosis, in which hypoxia levels are extremely high, causing low responsiveness to chemotherapy and conferring basic resistance to anti-cancer drugs. Programmed death ligand 1 (PD-L1)-mediated immune escape may be an underlying source of resistance and a suitable target for specific therapy, but its role in PPCs is unclear.', 'In total, 122 PPCs were investigated. Paraffin-embedded tumour sections were stained with PD-L1 and hypoxia-inducible factor-1α (HIF-1α) antibodies. Overexpression was denoted by moderate-to-strong PD-L1 membrane staining in ≥5% of tumour cells and HIF-1α nuclear staining in ≥10% of tumour cells. The presence of driver mutations in the epidermal growth factor receptor (EGFR), Kirsten rat sarcoma viral oncogene homolog (KRAS), v-raf murine sarcoma viral oncogene homolog B (BRAF), telomerase reverse harscriptase gene (TERT), phosphoinositide 3-kinase catalytic alpha (PIK3CA), anaplastic lymphoma kinase (ALK), and ROS1 (ROS1 proto-oncogene receptor tyrosine kinase) genes were examined.', 'The overall frequencies of PD-L1 and HIF-1α overexpression and EGFR mutation were 70.5, 75.4, and 22.1%, respectively. High PD-L1 expression was significantly correlated with that of HIF-1α (p\xa0<\xa00.001) and tumour necrosis (p\xa0<\xa00.001). HIF-1α expression was associated with EGFR mutation (p\xa0=\xa00.015). Advanced stage and high PD-L1 expression were two independent risks for poor overall survival.'] Does high co-expression of PD-L1 and HIF-1α correlate with tumour necrosis in pulmonary pleomorphic carcinoma?