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Metastatic colorectal carcinoma presenting with mucobilia

A 62-year-old man presented with a history of recurrent bouts of upper abdominal pain and episodes of jaundice. Six years previously, he had undergone an abdominoperineal resection for a T3N1 moderately differentiated low rectal carcinoma. Post-operatively, he was treated with adjuvant radiation therapy and 6 months of intravenous 5-fluorouracil. He completed therapy without complication and remained well for 3 years when he represented to his local hospital with an episode of upper abdominal pain. Carcinoembryonic antigen and computed tomography (CT) scan of the abdomen were normal. He had a further attack of pain 1 year later, which was selflimiting and another attack the following year. During this latest attack, his liver functions were noted to be transiently abnormal and CT scan of the abdomen showed mild dilatation of the segment 2 and 3 bile ducts with no associated mass. Endoscopic retrograde cholangiopancreatography (ERCP) was undertaken, which showed a significant amount of mucoid material and a diagnosis of biliary obstruction caused by sludge was made (Fig. 1). A laparoscopic cholecystectomy was undertaken without complication. However, he continued to represent with five further episodes of upper abdominal pain and associated obstructive liver function tests. Five further ERCPs were performed all with the finding of biliary obstruction caused by mucoid material as well as a magnetic resonance cholangiopancreatography with similar findings. A hepatobiliary opinion was sought and his cross-sectional radiology was reviewed. This showed obvious dilatation of the segment 2 and 3 ducts without any mass lesion (Fig. 2). Review of serial imaging showed this dilatation to be progressive. His carcinoembryonic antigen was 3 mg/L (normal range <3 mg/L) and Ca19-9 was mildly elevated at 120 U/mL (normal range <25 U/mL). A diagnosis of a mucinous tumour involving the left bile duct was made and the patient came forward for a left hepatectomy with caudate lobectomy, portal lymph node dissection and exploration of the common bile duct. The operative findings were of an atrophied left lobe with multiple prominent surface bile ducts. On intraoperative ultrasound biliary dilatation could be seen but no mass lesion was present in the bile duct or hepatic parenchyma. The right side of the liver was normal. Post-operatively, the patient made a good recovery and was discharged well. The pathology showed multiple small nodules within the left lobe parenchyma 4–5 mm in diameter, which on microscopy were mucinfilled cysts lined by a pleomorphic papillary epithelium. The mucin also contained strands of a glandular epithelium (Fig. 3). Perineural invasion was present. The left bile duct contained mucin and a number of small cysts that communicated with the biliary tree. Immunohistochemistry of the glandular elements showed positive staining for CK20, no expression of CK7 and positive staining for CDX2 indicating that the tumour was of colorectal origin rather than biliary origin. The propensity of metastatic colorectal carcinoma to involve the bile ducts was first highlighted by Povoski et al. by describing 15 patients presenting with intrabiliary tumour growth. This can take the form of solid growth of tumour extending down the bile duct and causing obstruction, mass effect of large volume metastases