CD274 and squamous cell carcinoma: We further investigated the potential impact of different types of cytological specimens (PE vs. BB vs. BAL), different types of biopsies (bronchial biopsy vs. transthoracic core biopsy), and histological tumour type (adenocarcinoma vs. squamous cell carcinoma) on cyto-histological concordance of PD-L1 expression in NSCLC.