Expression Of Delta-Like Protein 3 Is Reproducibly Present In A Subset Of Small Cell Lung Carcinomas And Pulmonary Carcinoid Tumors

•Interobserver agreement for DLL3 expression is substantial among thoracic pathologists.•High DLL3 expression (≥ 50% of tumor cells) is observed in almost 80% of small cell lung carcinomas.•Approximately one third of atypical and typical carcinoid tumors show high DLL3 expression.•High DLL3 expression is associated with better overall survival in small cell lung carcinomas.