Intramural cyst of the bile duct demonstrated by cholangioscopy and intraductal US.

Acute biliary pancreatitis developed in an 80-year-old man who had a history of hypertension, coronary artery disease, moderate aortic stenosis, and benign prostatic hypertrophy. Serum bilirubin was 3.2 mg/dL (normal: 0.01.2 mg/dL), alanine aminotransferase 504 U/L (21-72 U/L), aspartate aminotransferase 728 U/L (17-59 U/L), alkaline phosphatase 141 U/L (35-125 U/L), and serum amylase 1095 U/L (0-140 U/L). ERCP, performed because of a rising bilirubin level, revealed stones in the proximal bile duct and possibly a stricture in the distal common bile duct. A 10F, 5-cm stent was placed after sphincterotomy and stone extraction, which resulted in normalization of the biochemical tests. The patient was then referred to our institution. EUS, performed because of the possibility of a mass involving the distal common bile duct, demonstrated a 1.8-cm by 1.6-cm hypoechoic focus around the stent in the head of the pancreas that was thought to be inflammatory in nature. There was no associated lymphadenopathy. Numerous stones were noted in the gallbladder. Three months later laparoscopic cholecystectomy was attempted, but the operation was converted to an open procedure because of dense adhesions in the right upper quadrant. Bile duct exploration was not carried out because of moderate intraoperative bleeding from the site of cystic artery ligation, which necessitated abbreviation of the procedure. The patient had an uneventful recovery. ERCP for stent removal and re-evaluation of the bile duct was performed 2 months after cholecystectomy. This demonstrated a new 8-mm diameter smooth, hemispheric filling defect in the mid portion of the common bile duct that appeared to be adherent to the lateral wall. It could not be moved with an 8.5-mm extraction balloon catheter. The previously noted distal stricture was not evident. Cytologic specimens obtained by brushing and biopsies from the bile duct lesion disclosed only reactive epithelial atypia. The stent was not replaced. Liver function tests had normal results. MRI did not demonstrate a mass at the level of the mid duct. However, the smooth, eccentric filling defect was demonstrated again 1 month later by ERCP, and transduodenal cholangioscopy was performed with a “baby” cholangioscope (CHF BP30, Olympus America Inc., Melville, N.Y.) inserted through a “mother” duodenoscope (TJF-100, Olympus) (Fig. 1). Direct visualization showed a round protuberance in the lumen with smooth overlying mucosa (Fig. 2). IDUS with a 20-MHz catheter probe (Olympus) (Fig. 3) demonstrated a 6-mm by 8-mm cyst within the duct wall with preservation of the normal overlying wall layer pattern (Fig. 4). The patient has remained asymptomatic for the last 6 months. No further evaluation is planned.