We report an interesting case of a patient with neither family nor personal history for pancreatic diseases that was admitted to our department in 1982, at the age of 25 years. At that time, medical history, absence of alcohol abuse, and radiological imaging suggested a diagnosis of idiopathic chronic pancreatitis. The patient underwent a left-pancreatectomy, with histological confirmation of chronic pancreatitis. He was asymptomatic until 1988, when episodes of pain arose, requiring a pancreatico-jejunostomy. No further problems ensued until 2004 when radiological investigation following pain-related symptoms revealed enormous dilation of the pancreatic duct. A pylorus-preserving pancreaticoduodenectomy resulting in total pancreatectomy was performed. Histological examination revealed an intraductal papillary mucinous non-invasive carcinoma. Review of the previously resected specimen revealed former misdiagnosis. This tumour usually affects an elderly population and nowadays is recognised as a possible cause of chronic obstructive pancreatitis. This report represents a slippery case of misdiagnosis and demonstrates that follow-up is always mandatory following a diagnosis of idiopathic chronic pancreatitis.