MUC5AC and pancreatic signet ring cell adenocarcinoma: Primary pancreatic signet ring cell carcinoma (PSRCC) is a scarce histopathological variation with an estimated incidence of less than 1% of pancreatic adenocarcinomas (PDAC) [1], which refers to the intra-cytoplasmic mucin vacuoles of more than 50% of mucin protein and the nucleus is squeezed sideways by the mucin to form a “signet ring” appearance [2].