Staining was completelyabsent in normal pancreas and pancreatitis, but frequent in pancreatic cancer.Membranous and cytoplasmic MUC5AC expression was most common in pancreaticadenocarcinomas (71% of 423), followed by carcinomas of the ampulla Vateri (43%of 47), and absent in six acinar cell carcinomas. Here, MUC5AC is linked to acinar cell carcinoma.