Cyst-Forming Intraductal Papillary Neoplasm of the Bile Ducts: Description of Imaging and Pathologic Aspects
AJR:197, November 2011
Jae Hoon Lim Yoh Zen Kee Taek Jang Young Kon Kim Yasuni Nakanuma
OBJECTIVE. Intraductal papillary neoplasm (IPN) of the bile duct is a newly described pathologic entity characterized by the presence of intraluminal tumors, which sometimes produce a large amount of mucin and form a cystic tumor. Cystic IPN of the bile duct is different from biliary cystadenoma or cystadenocarcinoma in that the former produces intraductal microscopic and macroscopic papillary tumors without ovarian-like stroma, whereas the latter produce a mucin-containing septate cystic tumor without communication with bile duct and with ovarian-like stroma in the cyst wall. The purpose of this study was to evaluate the potential relationships between cyst-forming IPNs of the bile duct and peribiliary glands and also intraductal papillary mucinous neoplasms of the pancreas.
MATERIALS AND METHODS. From a cohort of 87 patients with surgically resected and pathologically proved IPN of the bile duct, 12 patients with cystic IPN of the bile duct who underwent CT (n = 12), MRCP (n = 3), ultrasound (n = 3), and ERCP (n - 4) were included. Imaging findings were evaluated for the relationship of cystic tumors to the bile ducts; in particular, a diver-ticulum-like appearance was considered as suggestive of the peribiliary gland origin. Pathologic examination was conducted, and both gross and microscopic findings were recorded.
RESULTS. Radiologic examination revealed aneurysm-like dilatation of the involved bile ducts in five patients and intrahepatic biliary cystic tumor in two patients. Interestingly, the remaining five patients had diverticulum-like cystic tumor with or without communication; one patient had a cystic tumor laterally attached to the extrahepatic bile duct. Histopathologically, cystic tumors are lined by atypical biliary epithelium showing intracystic papillary prolifera-tion, with an appearance similar to that of pancreatic intraductal papillary mucinous neoplasm.
CONCLUSION. This study suggests that cyst-forming IPN of the bile duct may be a biliary counterpart to pancreatic intraductal papillary mucinous neoplasm. In particular, at least some of the tumors seem to arise from peribiliary glands, and these cases might be a counterpart to branch-duct intraductal papillary mucinous neoplasm of the pancreas, given the histo¬logic similarity between peribiliary glands and pancreatic branch ducts.