Focal hepatic steatosis surrounding a metastatic insulinoma

Reported herein is a case of focal hepatic steatosis surrounding a metastatic insulinoma in the liver of a 69-year-old woman. The patient complained of losing consciousness after meals, and hypoglycemia and hyperinsulinemia were confirmed. On CT and abdominal angiography a mass, 1 cm in diameter, was seen in the tail of the pancreas. In the early phase of dynamic CT a mass, 5 mm in diameter, was seen in the liver. In the late phase this mass appeared to be 3 cm in diameter. An arterial calcium stimulation/venous sampling test showed insulin levels after calcium injections in the hepatic artery to be extremely high. Thus, the liver tumor was diagnosed as a metastatic insulinoma, and distal pancreatectomy and partial resection of the liver were performed. The pancreatic tumor cells were immunohistochemically positive for insulin. The liver tumor was pale yellow. A white area surrounded the tumor. Histologically, the liver tumor was an insulinoma and the white area was focal fatty change of the liver. High insulin levels are said to inhibit oxidation of free fatty acids into triglycerides, causing free fatty acids to accumulate in hepatocytes. Focal hepatic steatosis caused by the local effects of insulin can present as a focal rim surrounding a metastatic insulinoma.