Carcinoma related to choledochal cysts with internal drainage operations.

Carcinoma arising in a choledochal cyst retained after enteric drainage is discussed in comparison with primary carcinoma. In our series, carcinoma developed in eight of 82 patients with choledochal cyst and three of the eight had secondary carcinoma occurring several years after enteric drainage. Forty-two similar instances and 235 instances of primary carcinoma have been reported in Japan. The mean age at detection of carcinoma in enteric drainage was 35 years old, 15 years less than that of primary carcinoma. The mean interval between drainage and detection of carcinoma was ten years. Carcinoma mainly arose from the retained cyst in drainage, while primary carcinoma developed in either the cyst or gallbladder. The prognosis was very poor. Almost all patients undergoing enteric drainage died soon after the detection of carcinoma. This is possibly due to the delay in diagnosis. Pancreatic juice can easily regurgitate into the choledochus through an anomalous junction of the pancreatobiliary ductal system, and enteric drainage causes pancreatic juice in the cyst to become activated due to the influx of intestinal juice. Therefore, inflammatory changes of the cyst are accelerated and probably result in carcinoma. Early excision of the choledocus should be recommended in patients with choledochal cyst retained after enteric drainage.