Three cases of pancreatic pseudocysts mimicking mucinous cystadenoma and pancreatic cancer on Endoscopic Ultrasound

Purpose: Pancreatic pseudocysts, which account for 70 to 90% of pancreatic cystic lesions, are non-epithelially lined cystic cavities contiguous with the pancreas. Pancreatic pseudocysts can be caused by acute, chronic or traumatic pancreatitis and should be differentiated from other pancreatic diseases with cystic appearances, especially macrocystic neoplasms. We report three cases of pancreatic pseudocysts mimicking mucinous cystadenomas and pancreatic cancer.

Results: Case 1, A 39-year-old woman was admitted to the hospital with severe constipation. The abdominal CT scan revealed 36mm diameter cystic mass at pancreas head and the EUS showed an anechoic lesion of 37×30mm with solid, papillary projection from cyst wall on the pancreas head. There were no other findings compatible with pancreatitis. The patient underwent PPPD with pre op diagnosis of mucinous cystadenoma. Final post op diagnosis of the resected cystic lesion was compatible for pseudocyst.

Case 2, A 76-year-old woman visited with right upper quadrant pain. The abdominal CT scan showed 44×32mm diameter round cystic mass at pancreas tail with smooth margin and mild parenchymal atrophy without calcification. The EUS revealed thin-walled, round anechoic lesion of 38×34mm with several internal septums compatible with mucinous cystadenoma. We considered the pancreas parenchymal atrophy as aging process because she had no history of pancreatitis. She did't undergo operation for age. However, on the 6 months later EUS, pancreatic cystic lesion was spontaneously decreased to 13×10mm sized. So, we considered the patient's final diagnosis was chronic pancreatitis with pseudocyst.

Case 3, A 55-year-old man was referred to our hospital for further evaluation of pancreatic cystic tumor. The patient initially visited another hospital because of upper abdominal pain. The abdominal CT scan revealed 1.7cm diameter well-marginated, round, round, low density lesion on the pancreatic body compatible with a cystic lesion therefore he was referred to our hospital. The EUS described a 17×19mm solid, round hypoechoic lesion. There were no other findings compatible with pancreatitis. The ERCP revealed mild displacement of the main pancreatic duct of the body due to a mass effect, but no cyst filling. The patient underwent laparoscopic body and tail pancreatectomy due to concern for solid pancreatic neoplasm. On pathologic examination, the pancreatic groß specimen revealed a well-encapsulated, unilocular cystic lesion filled with yellowish muddy material. Microscopic findings of the resected cystic lesion were compatible for pseudocyst filled with semisolid lipids.

Conclusions: We report the three cases of pancreatic pseudocysts appeared by EUS as a mucinous cystadenoma and pancreatic cancer which were therefore resected.