A Case of Pancreaticobiliary Adenocarcinoma Secondary to Malignant Transformation of Remnant Tissue From a Type I Choledochal Cyst

Abstract

Introduction: Surgical resection of the choledochal cyst reduces but does not eliminate the risk of malignant transformation, suggesting the important role of continued surveillance. Case presentation: A 38-year-old man with a history of cadaveric liver allograft and a peripancreatic cystic mass presented with right upper quadrant abdominal pain, nausea, and involuntary weight loss. Eight years prior, the patient suffered from acute cholangitis and hepatic failure. He was diagnosed with a type I choledochal cyst. He underwent liver transplantation with cyst resection. Hepatic fibrosis and cholangitis were identified. A surveillance abdominal CT later revealed a 12-mm hypodense cystic lesion at the head of the pancreas. Differential diagnoses considered were intraductal papillary mucinous neoplasm (IPMN) and pancreatic pseudocyst. Abdominal MRCP later demonstrated a larger cystic mass with a tubular connection to the main pancreatic duct, suspicious for branch duct IPMN. Fine needle aspiration (FNA) of the cyst was not diagnostic. The physical exam revealed a tender abdomen at the right upper quadrant, without a palpable mass or jaundice. Laboratory studies revealed an elevated serum alkaline phosphate level and otherwise normal liver function tests. Serum CEA and CA-19-9 levels were elevated. The abdominal CT demonstrated a heterogeneous hypodense solid mass at the pancreatic head with surrounding desmoplastic reaction, portal vein invasion, regional adenopathy, and multiple liver lesions. Deep FNA was performed on one liver lesion: Metastatic pancreaticobiliary adenocarcinoma was diagnosed. The patient was initiated on chemotherapy, but the disease continued to progress. Discussion: We report a case of adenocarcinoma of pancreaticobiliary origin, secondary to malignant transformation of presumed remnant tissue from a type I choledochal cyst, despite efforts in surveillance. The choledochal cyst, a congenital abnormality from embryological development, is usually a pediatric diagnosis. The Todani classification delineates different anatomical features of a choledochal cyst. Complications include acute cholangitis and hepatic injury with fibrosis. While the management is generally early surgical resection due to the risk of malignant transformation to cholangiocarcinoma, removal does not eliminate the risk entirely, as remnant tissue could transform. Therefore, close surveillance remains a priority after resection of a choledochal cyst.Figure 1Figure 2Figure 3