A 48-year-old woman, a smoker of 10 cigarettes a day with a history of COPD and intraductal breast carcinoma, was admitted for acute pancreatitis. A CT scan revealed a prominent pancreatic head with inflammatory changes in the surrounding fat, causing dilation of the pancreatic duct (duct of Wirsung). These findings could be related to a focal area of ​​chronic pancreatitis, although an underlying neoplastic lesion could not be ruled out. An MRI was performed, yielding similar results. An endoscopic ultrasound was then performed, revealing marked signs of chronic pancreatitis, with intraparenchymal and intraductal stones and secondary dilation of the main pancreatic duct. Although no clear lesion was observed in the prominent area in the head, a biopsy was performed, with histology consistent with chronic pancreatitis. Two months later, the patient was admitted for painless jaundice with bilirubin up to 13 mg/dL, which improved spontaneously to 4 mg/dL. During this admission, CT and MRI scans were repeated, which were similar to the previous ones except for now showing dilation of the biliary tract. The echoendoscopy was repeated, without identifying a clear lesion in this exploration either, but a puncture was again performed in the head of the pancreas in the area adjacent to the amputation of the common bile duct, and on this occasion findings compatible with pancreatic ductal adenocarcinoma were observed. Following this, the patient underwent surgery, performing a cephalic duodenopancreatectomy with histology compatible with well-differentiated pT2N1 ductal pancreatic adenocarcinoma with low-grade PanIn in contact with the pancreatic margin; after surgery, treatment was initiated by oncology with FOLFIRINOX, with good clinical evolution.

This case demonstrates how challenging it is to diagnose a pancreatic tumor when it is located within a pancreas with advanced chronic pancreatitis. In our case, jaundice was the alarming sign that made us reconsider the case; a new endoscopic ultrasound with puncture was performed, using the amputation of the common bile duct as a guide when selecting the area to be biopsied, thus resulting in a correct diagnosis with the subsequent establishment of treatment.