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

Abstract

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.

Unusual imaging findings of pancreatobiliary‐type intraductal papillary mucinous neoplasm

“…In most cases, these tumors are diagnosed after progression to invasive cancer 5 . Therefore, high‐grade dysplasia of pancreatobiliary‐type IPMN, as demonstrated in this case, has rarely been reported 6 …”

“…5 Therefore, high-grade dysplasia of pancreatobiliary-type IPMN, as demonstrated in this case, has rarely been reported. 6…”

Text-based Integration of Mutational Profiles for Classification and Biomarker Identification of Intraductal Papillary Mucinous Neoplasms of the Pancreas

“…These genes could promote tumor growth and progression by repressing apoptosis instead of cell proliferation (46). A case study on a resected two-branch duct-type IPMNs showed concurrent activation of genes in the same family (MUC5AC and MUC6), for high-grade dysplasia (54). Thus, we believe that an extension to study the whole MUC family could reveal biological evidence for IPMNs grading, which is worth exploring in future research.…”