A case of pancreatic neuroendocrine tumor with massive cystic degeneration misdiagnosed as a pancreatic pseudocyst

A 55yearold man was hospitalized for evaluation of cystic lesion at the pancreas tail (Figure 1). The presumed diagnosis of the pancreatic cyst was pseudocyst because it was a unilocular cyst with debris inside, and the patient was a chronic alcoholic with a recent history of acute pancreatitis. Since the patient had no symptom related with the cyst, he was followed up with alternative CT scan and EUS for 15 months, however, the size of the cyst increased gradually. In EUS imaging, a very thickwalled unilocular cyst was observed with a large amount of echogenic material inside (Figure 2). There was no mural nodule inside the cyst and no communication between the cyst and the pancreatic duct. The main pancreatic duct showed normal caliber. Serum CA 199, amylase, and lipase levels were within the normal limits.