Epigastric Pain and Jaundice in Patient with Colorectal Adenocarcinoma, with Rare Site of Metastasis

Abstract

Introduction: Jaundice in patients with colon cancer is usually a result of intrahepatic metastases. Sometimes, it can be caused by extrahepatic obstruction from metastatic lymph nodes. A rarer cause of jaundice in these patients is solitary bile duct metastasis mimicking cholangiocarcinoma. We present a case that demonstrates this, and the steps involved in making an accurate diagnosis. Case Presentation: A 58 year old female with history of colon cancer post resection ten years ago presented with epigastric abdominal pain and jaundice. MRCP showed no liver lesions, but a 15 mm mass located at the pancreatic head or common bile duct concerning for a pancreatic or bile duct neoplasm. EUS was done which showed a 12.5 x 9.8 mm hypoechoic distal bile duct mass. Samples were obtained via FNA which were positive for adenocarcinoma with tumor cells positive for CK20 and CDX2, consistent with intestinal differentiation and negative for CA19-9 and CK7. Discussion: A solitary bile duct tumor from metastatic colon cancer without any hepatic lesions is an unusual finding and can resemble cholangiocarcinoma. These metastasis present, on average, about 45 months after resection of the primary colon tumor. There should be a high index of suspicion for recurrence of primary colon tumor in these patients if they present with a biliary neoplastic lesion due to the treatment implications involved. The histologic findings can also appear similar. Obtaining adequate tissue sample is made possible by EUS/FNA which allows immuno-histochemical staining for intestinal and bile duct markers. The colorectal epithelium is reactive to cytokeratin-20, but not to cytokeratin-7 which stains positive for biliary epithelium. Therefore, a cytokeratin 20-positive and cytokeratin 7-negative immuno-histochemical staining pattern is characteristic of biliary metastasis from colorectal cancer. The expression of CDX2 in adults is restricted to the intestine, from the duodenum to the rectum. CDX2 is regarded as a specific marker of the intestinal epithelial cells that can be utilized for identifying the colorectal origin of metastatic adenocarcinomas. The tumor in our patient stained positive for CK20 and CDX2, thus confirming colorectal origin.Figure 1Figure 2Figure 3