MUC5AC and neoplasm: We did not subclassify into peritumoural and intra-tumoural budding because of difficulties in defining the edge of the tumours and the frequent observation of intra-tumoural buds in PDAC.8, 9 Grading of PDAC according to the WHO26 includes the semi-quantitative assessment of mucin production, mitoses, nuclear atypia and glandular differentiation.27 Poorly differentiated tumours contain poorly formed glands and can show individual infiltrating cells and solid areas.