MUC5AC and neoplasm: The Carneiro system distinguishes 4 categories of gastric tumours: glandular, isolated cell, solid and mixed, based on their immunophenotype such that it further divides the Laurén intestinal subtype into tumours with intestinal, gastric or mixed differentiation, according to the expression of specific markers (MUC6, MUC5AC mucins and TFF1 peptide gastric markers or MUC2, CDX2, CD10 and pepsinogen-1 intestinal markers, amongst others) [3].