# A missed case of intraductal oncocytic papillary neoplasm associated with missed stones in extrahepatic bile duct: a case report

## TL;DR

A case report describes a rare bile duct tumor missed due to gallstones, successfully diagnosed and treated with specialized endoscopy.

## Contribution

Highlights the diagnostic value of peroral choledochoscopy in identifying IOPN when preoperative evidence is lacking.

## Key findings

- IOPN was confirmed after gallstone removal using choledochoscopy and pathological examination.
- Choledochectomy was performed successfully with no recurrence observed at 6 months.
- Peroral choledochoscopy proved effective for diagnosing biliary tumors in complex cases.

## Abstract

The pathological features of intraductal oncocytic papillary neoplasm (IOPN) of the bile duct include tumor cells that are rich in eosinophilic cytoplasm and arranged in papillary structures. Herein, we report a missed case of IOPN of the bile duct because of concomitant gallstones. A 70-year-old woman was hospitalized with upper abdominal discomfort. The primary diagnosis was choledocholithiasis following imaging examination. However, an unidentified mass was detected after the gallstones were removed. The mass appeared as many papillary protuberances surrounded by fish-egg-like mucosa when viewed by the choledochoscope and was confirmed as IOPN by pathological examination. The patient underwent choledochectomy and no recurrence was observed at the 6-month follow-up examination. In this report, peroral choledochoscopy demonstrated its advantages for the diagnosis of biliary diseases and acquisition of tissue specimens. Therefore, it may solve the challenge related to the lack of preoperative pathological evidence for bile duct tumors.