In total, four out of the eight ampullary SRCs showed poorly differentiated adenocarcinoma with prominent signet ring cell features; of these, three showed CK7+, CK19+ and MUC1+ staining (cases 5, 3 and 6; Fig. 1) and one case showed positive immunoreactivity for CD10 (case 3). Here, MUC1 is linked to adenocarcinoma.