We describe a case of relapsing acute pancreatitis apparently idiopathic in a 55-year-old man. The patient did not smoke and was a modest and irregular drinker of wine. Endoscopic retrograde cholangiopancreatography showed an initial dilatation of secondary ducts like a chronic pancreatitis of class I of Cremer. Ultrasound and computed tomography resulted negative for pancreatic lesions. In the follow-up however, magnetic resonance cholangiopancreatography detected the presence of an intraductal mucin-hypersecreting neoplasm, a duct-ectatic mucinous cystic tumor of the pancreas, in the uncinate process. This is a benign lesion clearly recognized nowadays by magnetic resonance cholangiopancreatography, because this radiological technique shows the grape-like clusters of cystic lesions in secondary ducts communicating with the main duct on the same plane. The radiological picture above excludes a malignant lesion and a biopsy specimen is not required. Furthermore, an intraductal mucin-hypersecreting neoplasm of the pancreas does not require an immediate surgical resection because of its slow evolution and can be followed-up. Conversely cystoadenocarcinoma spreads in peripheral ducts and does not communicate with the Wirsung duct. It requires both surgical resection and a biopsy specimen for histological diagnosis. In the last episode of acute pancreatitis, a sphincterotomy was performed at endoscopic retrograde cholangiopancreatography and our patient had no more pain for one year.