Cystadenoma of the common bile-duct with malignant transformation.

A case of cystadenoma of the common bile-duct with areas of carcinoma in situ in a 61 year old woman is presented. Pre-operative investigations may confuse this rare tumour with the more common choledochal cyst although this case raises the possibility that this neoplasm may have arisen within a longstanding choledochal cyst. Due to the risk of malignant transformation, complete excision of any cystic lesion of the bile-duct is recommended.