A variety of hepatobiliaryand pancreatic neoplasms are mucin producingand have been associated with the development ofmucobilia including biliary mucinosis, biliary papillomatosis,mucin-producing cholangiocarcinoma(MPCC), or cystic neoplasms of the pancreas orbiliary tree (cystadenoma or cystadenocarcinoma).We report the case of 46 year-old male with a biliarycystadenocarcinoma of the caudate lobe which resultedin chronic biliary obstruction and relapsingcholangitis. The gene discussed is MUC5AC; the disease is cystadenoma.