Heterotopic Gastric Mucosa in a Duplication Cyst of the Common Hepatic Duct Mimicking Cholangiocarcinoma.

Heterotopic gastric mucosa in biliary tract is a congenital anomaly that can prove significant clinical dilemmas. Here we report the case of a 28-year-old female patient presenting with jaundice, pruritus, and altered liver tests, with predominant cholestasis. Liver biopsy revealed histological changes suggesting large bile duct obstruction with advanced fibrosis. At imaging, common hepatic duct stricture due to an intraluminal enhancing mass was observed. Endoscopic retrograde cholangiopancreatography and upper echoendoscopy revealed a firm mass of the common hepatic duct with a complete obstruction, suspicious for cholangiocarcinoma. Fine-needle aspiration biopsy performed under echoendoscopic guidance revealed fundic type gastric mucosa. Despite histological result, radiological suspicion of malignancy together with advanced fibrosis prompted a segmental resection of biliary tract. At macroscopic examination, the common hepatic duct presented a focal pseudocystic appearance with a firm zone of subtotal stenosis. Histology revealed a duplication cyst lined by heterotopic fundic gastric mucosa. Heterotopic gastric mucosa of the biliary tract should be suspected in young patients without know risk factors for hepatobiliary malignancies. Imaging and careful histological examination are mandatory for optimal management. Liver fibrosis, secondary to chronic biliary obstruction may be a significant late complication.