Immunohistochemistry, hepatocyte nuclear factor 1 beta (HNF1B) expression, and k-ras mutational analysis are complementary methods to differentiate primary pancreatic clear cell carcinoma from other pancreatic tumors, conventional ductal adenocarcinoma, and metastatic clear cell carcinomas of other locations [14-16]. This evidence concerns the gene HNF1B and invasive ductal breast carcinoma.