Simple mucinous cyst with a difficult pre-operative diagnosis: A case report

Abstract

A 70s-year-old woman with acute cholecystitis was admitted to our hospital. Computed tomography (CT) revealed a cystic lesion in the tail of the pancreas. Post-cholecystectomy, dynamic CT revealed a 27 mm cystic lesion with a thickened, contrast-enhanced wall. Magnetic resonance imaging confirmed a unilocular lesion with no diffusion restriction. Endoscopic ultrasonography demonstrated a cystic lesion without a "cyst-in-cyst" appearance. Endoscopic retrograde pancreatography did not reveal mucin in the pancreatic duct or communication with the lesion. The preoperative differential diagnoses included a mucinous cystic neoplasm or cystic degeneration of a solid tumor. The patient underwent distal pancreatectomy. Histopathological examination confirmed the lesion as a simple mucinous cyst (SMC), lacking ovarian-like stroma and with gastric-type mucinous epithelium. SMC is challenging to diagnose pre-operatively, but it is crucial to differential diagnoses. SMC shares mucinous features with branch-duct intraductal papillary mucinous neoplasm (BD-IPMN); therefore, further investigation into its potential association with pancreatic cancer is warranted.