A case of a pancreatic pseudocyst associated with alcoholic chronic pancreatitis that mimicked a mucinous cystic neoplasm.

Distinguishing true cysts from pseudocysts can be challenging in clinical practice. We report a patient with a pancreatic pseudocyst secondary to alcoholic chronic pancreatitis that closely mimicked a mucinous cystic neoplasm. A 64-year-old woman with a medical history of alcoholic liver cirrhosis had a progressively enlarging pancreatic cyst in the pancreas body associated with elevated serum carbohydrate antigen 19 - 9 levels. Computed tomography indicated a multilocular cystic lesion with calcification, thickened septa, and protruded lesion. Endoscopic ultrasonography revealed a protruded lesion within the cyst showing detectable blood flow and the cystic lesion had no communication with the main pancreatic duct. Endoscopic ultrasonography showed honeycombing lobularity and strand-like hyperechoic structures in the pancreatic parenchyma. We determined a mucinous cystic neoplasm diagnosis, which cannot rule out malignancy. Distal pancreatectomy with splenectomy was performed. The histopathological examination revealed fibrosis within the pancreatic parenchyma surrounding the cyst as well as fibrin and material suggestive of pancreatic stones along the inner wall. The pancreatic duct was communicated with the cyst and epithelial lining of the cyst wall was not identified, leading to a pancreatic pseudocyst diagnosis. Even when MCN-like features are present in patients with chronic pancreatitis as an underlying disease, it is difficult to completely rule out pancreatic pseudocysts.