A 58-year-old farmer from rural Thailand presents with painless progressive jaundice and weight loss. Imaging shows an ill-defined mass at the hilum encasing the confluence of the right and left hepatic ducts. He gives a long history of eating raw freshwater fish. The infectious agent most strongly implicated in this malignancy is:

• A Schistosoma japonicum
• B Clonorchis sinensis ✓
• C Fasciola hepatica
• D Echinococcus granulosus

Explanation

The liver flukes Clonorchis sinensis and Opisthorchis viverrini, acquired by eating raw freshwater fish, are established risk factors for cholangiocarcinoma, particularly the periductal infiltrating and hilar (Klatskin tumor) types endemic in Southeast Asia. Chronic fluke infection causes ductal epithelial hyperplasia, periductal fibrosis, and oxidative DNA damage progressing to malignancy. Schistosoma japonicum affects the portal venous system causing pipe-stem fibrosis, Fasciola hepatica invades the biliary tree but is not linked to cholangiocarcinoma, and Echinococcus produces hydatid cysts.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.