A resected case of two branch duct-type intraductal papillary mucinous neoplasms showing different clinical courses after a two-year follow-up

Clin J Gastroenterol. 2017 Jun;10(3):274-278. doi: 10.1007/s12328-017-0728-1. Epub 2017 Mar 3.


The patient was a 60-year-old man without any particular complaints, but he underwent abdominal computed tomography (CT) and magnetic resonance cholangiopancreatography (MRCP) due to a fatty liver, which revealed two similar cystic lesions regarded as branch duct-type intraductal papillary mucinous neoplasm (BD-IPMN) in the pancreatic body [BD-IPMN (b), 16 mm in size] and tail [BD-IPMN (t), 13 mm in size] without a "high-risk stigmata" or "worrisome features". He subsequently received follow-up by MRCP every 6 months. Two years later, MRCP showed prominent dilation of the main pancreatic duct (MPD) and mural nodule formation within the dilated MPD adjacent to the BD-IPMN (b). Distal pancreatectomy specimens revealed that the BD-IPMN (b) was lined by low-papillary gastric mucinous epithelium with low-to-intermediate-grade dysplasia and involved the MPD, forming a malignant mural nodule showing pancreatobiliary-type IPMN. In contrast, the BD-IPMN (t) was lined by flat, monolayer columnar gastric mucinous epithelium without atypia, which suggested the possibility of a "simple mucinous cyst". A genetic analysis showed KRAS mutation only in BD-IPMN (b). Differences in the histological and genetic findings between two similar BD-IPMNs in the present case may suggest what kinds of examinations should be performed in patients with BD-IPMNs without any worrisome features.

Keywords: Brunch duct-type IPMN; KRAS mutation; Malignant mural nodule; Simple mucinous cyst.

Publication types

  • Case Reports

MeSH terms

  • Carcinoma, Pancreatic Ductal / diagnostic imaging
  • Carcinoma, Pancreatic Ductal / pathology
  • Carcinoma, Pancreatic Ductal / surgery*
  • Humans
  • Male
  • Middle Aged
  • Mucus / metabolism
  • Pancreatic Ducts / diagnostic imaging
  • Pancreatic Ducts / pathology
  • Pancreatic Neoplasms / diagnostic imaging
  • Pancreatic Neoplasms / pathology
  • Pancreatic Neoplasms / surgery*
  • Tomography, X-Ray Computed