Diffuse Involvement of Mixed-Type IPMN

Abstract

Introduction: The malignant potential of intraductal papillary mucinous neoplasm (IPMN) of the pancreas is associated with involvement of the main pancreatic duct. We present a case of a multi-cystic IPMN involving the main pancreatic duct and its side branches. Case: A 72-year-old male with a medical history of stroke and tobacco use presented with a 3-week history of abdominal pain, along with unintentional weight loss of 40 lbs over the last year. A CT scan showed a grossly abnormal pancreas with a multi-macrocystic mass centered at the head of the pancreas, measuring approximately 5.7 cm x 7.0 cm. The extrahepatic and intrahepatic bile ducts demonstrated marked dilatation. Laboratory evaluation was significant for total bilirubin 3.8 mg/dL, alkaline phosphatase 758 U/L, AST 79 U/L and ALT 107 U/L. The patient underwent EUS showing multi-cystic replacement of the majority of the pancreas parenchyma. The pancreatic duct was dilated to 12 mm in the head of the pancreas. The common bile duct was dilated to 17 mm and abruptly terminated in the head of the pancreas due to the obstructing cyst. Cyst aspirate was performed and sent for analysis. Cytology of the cystic fluid showed acute inflammatory cells and proteinaceous debris, suggestive of a pseudocyst. The fluid amylase and CEA were elevated to 10,205 U/L and >1500 ng/mL, respectively. Serum CA 19-9 was elevated to 230 U/mL. These findings are consistent with a mixed-type IPMN, which has a similar risk for malignancy as a main-duct IPMN. According to the Fukuoka guidelines, this patient had high-risk stigmata of malignancy including obstructive jaundice and main pancreatic duct > 10 mm. Therefore, he underwent a total pancreatectomy with pathology revealing invasive mucinous carcinoma arising in the background of extensive IPMN. The surgical margins were free of involvement, and he is being treated with adjuvant chemotherapy. Discussion: Multi-cystic lesions of the pancreas can often appear as pseudocysts, but may in fact represent mixed-type IPMN. Most IPMNs are solitary, but 5-10% involve the entire gland. Further evaluation of these lesions is essential, as mixed-type IPMN carries a similar risk of malignancy as main-duct IPMN.Figure 1Figure 2Figure 3