A 56-year-old man comes to the office due to 3 weeks of right upper quadrant abdominal pain and 6.6 kg (14.5 lb) of weight loss. Over the last week, he has noticed jaundice and dark urine. The patient has a history of ulcerative colitis in remission and hypertension. He does not use tobacco, alcohol, or illicit drugs. Temperature is 37 C (98.6 F), blood pressure is 110/74 mm Hg, and pulse is 80/min. BMI is 21 kg/m². The patient appears cachectic. Hepatomegaly is present, but there is no ascites. Laboratory results are as follows: CT scan of the abdomen reveals dilated intrahepatic ducts and a normal-sized common bile duct. Carcinoembryonic antigen and CA 19-9 levels are elevated, and serum alpha-fetoprotein level is normal. What is the most likely diagnosis?

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Explanation: 11ec25c8_d8e1_8dc2_bc81_ab46ad356d22_MD0003_00 This patient's ulcerative colitis, subacute right upper quadrant pain, weight loss, biliary obstruction (eg, jaundice, elevated alkaline phosphatase, dilated intrahepatic ducts), and elevated carcinoembryonic antigen (CEA) and CA 19-9 levels raise strong suspicion for cholangiocarcinoma, a highly lethal malignancy of the bile duct epithelium. Risk is greatest in those with fibropolycystic liver disease or primary sclerosing cholangitis, an inflammatory disorder of the biliary tree that is almost always (~90%) associated with underlying ulcerative colitis. Patients with cholangiocarcinoma generally come to clinical attention late in the disease course when the tumor obstructs biliary drainage, which leads to: Abdominal pain Weight loss Hyperbilirubinemia (jaundice, dark urine, pruritus) Cholestatic liver enzyme pattern (elevated alkaline phosphatase, normal/mildly elevated transaminases) Hepatomegaly/palpable right upper quadrant mass CEA, CA 19-9, and alpha-fetoprotein (AFP) can help differentiate cholangiocarcinoma (↑ CEA/CA 19-9, normal AFP) from hepatocellular carcinoma (normal CEA and CA-19, sometimes ↑ AFP). Abdominal imaging typically shows intrahepatic or common bile duct dilation (depending on the level of the lesion) and biliary mass. Endoscopic ultrasound or endoscopic retrograde cholangiopancreatography is then required for tissue diagnosis. (Choice B) Choledocholithiasis (gallstones in the common bile duct) usually presents with acute right upper quadrant pain, nausea/vomiting, and a cholestatic liver enzyme pattern. However, CEA and CA-19 are not typically elevated, and cachexia is unusual. (Choice C) Hepatocellular cancer usually occurs in the setting of alcoholism or chronic viral hepatitis. Although it can cause subacute right upper quadrant pain, weight loss, and cachexia, imaging typically reveals a focal mass in the liver. In addition, CEA and CA 19-9 are rarely elevated, but AFP is elevated in ~50% of cases. (Choice D) Colon cancer often metastasizes to the liver and is frequently associated with CEA and/or CA 19-9 elevation. However, metastatic disease to the liver usually causes multiple liver masses. (Choice E) Cancer in the head of the pancreas can obstruct the common bile duct, leading to signs of biliary obstruction and subacute right upper quadrant pain. Although pancreatic cancer often increases CA 19-9, imaging generally shows common bile duct dilation (the obstruction occurs in the distal biliary tree). Educational objective: Cholangiocarcinoma, a biliary tract epithelial malignancy, most often occurs in those who have fibropolycystic liver disease or primary sclerosing cholangitis due to underlying ulcerative colitis. Most cases present with subacute right upper quadrant pain, weight loss, and signs of biliary obstruction such as jaundice, cholestatic liver enzyme pattern, and dilation of the intrahepatic or common bile duct.

A 56-Year-Old Man Comes to the Office Due to 3