Background/Aims: Programmed death-ligand 1 (PD-L1) expression in tumor cells is associated with a poor biliary tract cancer (BTC) prognosis; tumor-infiltrating immune cells in the tumor microenvironment are associated with a better prognosis. The effect of PD-L1 expression on immune cells on survival is unclear. We investigated the relationship between PD-L1 expression in immune cells and BTC prognosis. Methods: PD-L1 expression was evaluated using an anti-PD-L1 22C3 mouse monoclonal primary antibody, and its relationships with clinical characteristics and prognosis were analyzed using the Cox proportional hazard model to investigate the prognostic performance of PD-L1 in BTC. Results: Among 144 analyzed cases, patients with positive PD-L1 expression in tumor cells and negative PD-L1 expression in immune cells showed poorer overall survival rates than those exhibiting other expressions (tumor cells: hazard ratio [HR]=1.023, p<0.001; immune cells: HR=0.983, p=0.021). PD-L1 expression in tumor cells was an independent predictor of poor overall survival (HR=1.024, p<0.001). In contrast, PD-L1 expression in immune cells was a predictive marker of good prognosis (HR=0.983, p=0.018). Conclusions PD-L1 expression in immune cells may be used as an independent factor to evaluate the prognosis of patients with BTC.

A small proportion of children with coronavirus disease 2019 (COVID-19) develop severe pneumonia. We reported the severe COVID-19 pneumonia in children aged <18 years with COVID-19 treated with remdesivir and dexamethasone from August 2021 to November 2021 by a retrospective review of their medical records. Eight children were included (5 males and 3 females). Their median age was 16 years (range: 9 to 17 years) and their median body mass index was 30.5 kg/m 2 (range: 22.8–38.5 kg/m 2 ). All patients had fever and dyspnea with hypoxia. Chest radiographic findings were variable and included diffuse or multifocal consolidation, nodules, and ground-glass opacities in the lungs. After receiving intravenous remdesivir and dexamethasone, 7 of the 8 children experienced an improvement in their symptoms within 2 days. In our case series, obesity was present in 6 out of 8 children with severe COVID-19 pneumonia.