Hepatic Duct Foreign Body Mimicking Cholangiocarcinoma: Case Analysis, Diagnostic Challenges, and Literature Review.

Foreign bodies in the biliary tract may provoke an inflammatory reaction, leading to lithogenesis followed by biliary obstruction with or without cholangitis. Such occurrences are typically associated with previous biliary surgery or endoscopic interventions, particularly cholecystectomy or endoscopic retrograde cholangiopancreatography (ERCP). Imaging studies, which usually provide valuable insights into biliary anatomy, may fall short in more difficult cases, making direct visualization of the biliary tree necessary. We present a case of an impacted bile duct stone in the right hepatic duct formed around a retained fragment of ERCP equipment left behind several years earlier. The patient presented with cholestasis and cholangitis. Magnetic resonance cholangiopancreatography (MRCP) revealed a bile duct stone embedded within a solitary hepatic duct stenosis, findings that were highly suspicious for the presence of cholangiocarcinoma. Thus, cholangioscopy was performed excluding malignancy and identifying the culprit. This procedure allowed the direct visualization of the stricture and acquisition of multiple biopsies. After hepatic duct dilatation and stone retrieval, a foreign body was identified in the stone core. The patient had rapid clinical improvement after stone extraction and remained asymptomatic during follow-up.  In conclusion, foreign bodies should also be part of biliary obstruction differential diagnosis, and no diagnostic modality should be excluded when pursuing a definite diagnosis.