Diffuse fatty degeneration often occurs after pancreaticoduodenectomy due to altered lipid metabolism and nutritional malabsorption. Focal fatty change of the liver is characterized by a well-demarcated region, and the pathogenesis remains unclear. A 60-year-old woman underwent pancreaticoduodenectomy for bile duct cancer 10 years before. During follow-up, an intrahepatic tumor was detected in the lateral segment in the liver. The differential diagnosis included cholangiocarcinoma and metastatic tumor on images of plain computed tomography, ultrasonography, and magnetic resonance angiography. The patient underwent lateral segmentectomy of the liver. The tumor was a soft yellow mass, and histological examination indicated focal fatty liver. It was thought that the fatty liver was caused by localized low blood supply and dysabsorption of lipoprotein after pancreaticoduodenectomy.