Villous tumor of the papilla of Vater presenting with hypopotassemia

We report a case of villous tumor of the papilla of Vater associated with hypopotassemia. The patient was a 73-year-old woman who presented with jaundice and fever. She had a history of diabetes mellitus and liver dysfunction. Laboratory studies revealed that levels of total bilirubin, alkaline phosphatase, and C-reactive protein, and the white blood cell count were elevated (suggestive of cholangitis) and that the serum potassium level was markedly reduced, to 1.9 mEq/l (normal value 3.5–5.0 mEq/l). Duodenoscopy showed a villous tumor arising in the papilla of Vater. Percutaneous transhepatic biliary drainage was performed. Approximately 700–1500 ml of bile with viscous mucoid fluid was drained daily. Percutaneous transhepatic cholangioscopy showed a papillary lesion in the distal common bile duct. Biopsied specimens from both percutaneous transhepatic cholangioscopy and duodenoscopy disclosed tubulovillous adenoma. Endoscopic ultrasonography showed that the tumor had spread to the main pancreatic duct as well as to the common bile duct. The patient underwent pylorus-preserving pancreaticoduodenectomy. Pathology examination disclosed well differentiated adenocarcinoma, carcinoma in situ, in tubulovillous adenoma. The cancer cells were observed at the bottom of the tumor spreading in the common bile duct. This is a rare case of a patient presenting with hypopotassemia associated with a tubulovillous tumor of the papilla of Vater that secreted mucoid material.