We present the case of an 88-year-old female, investigated for upper abdominal pain and upper abdominal mass, exhibiting at the computed tomography a large tumour located in the head of the pancreas, compressing the common bile duct and with uncertain preoperative diagnosis (benign/malign). The histopathological findings of the operative specimen (cephalic pancreatoduodenectomy) revealed a large serous multilocular cystadenoma. There are presented the clinical, imaging and pathological correlations in the present case, also analysing the limits of the imaging preoperative diagnosis and indications for surgery in cystic tumours of the pancreas.