A previously healthy, 59-year-old man suddenly developed epigastric pain followed by jaundice. Extensive clinical investigations suggested that the patient had a sclerosing cholangitis. At laparotomy, the extrahepatic bile ducts near their confluence were found markedly thickened. A biopsy specimen was obtained from the common bile duct. It showed a diffuse lymphohistiocytic infiltration, suggesting a lymphomatous infiltration. No evidence of a lymphoma was found in the abdominal cavity or in the retroperitoneal spaces. The clinical consensus at that time was that the patient had a primary sclerosing cholangitis involving the extrahepatic bile ducts. Biliary obstruction was released. Five months later, the patient developed a disseminated lymphoma, lymphohistiocytic, diffuse in type.