Pancreatic Pseudocyst Filled with Biliary Stones Mimicking a Pancreatic Groove Tumor: A Case Report.

Introduction: Reports of fistulas in the common bile duct caused by pancreatic pseudocysts have increased. However, to the best of our knowledge, no prior report has described pseudocysts filled with microbiliary stones that were difficult to differentiate from neoplastic lesions.

Case presentation: A 64-year-old man presented with groove pancreatitis attributable to heavy alcohol consumption and a hypovascular mass in the groove area with duodenal bleeding. The lesion, which was initially considered a pancreatic groove tumor with groove pancreatitis, was treated with subtotal stomach-preserving pancreaticoduodenectomy. However, a post-surgical pathological analysis revealed that it was a pancreatic pseudocyst in the groove area containing bilirubin calcium stones and pancreatic stones.

Conclusions: Cases comprising fistula formation in the common bile duct are rare. A pancreatic pseudocyst that formed a fistula with the common bile duct was suspected in the present case. This case was unique because the pseudocyst was filled with microbiliary stones. This report highlights the difficulty in differentiating a pseudocyst filled with bilirubin calcium stones from a neoplastic lesion and underscores the importance of the accurate diagnosis and management of this rare pathology.