Focal hepatic glycogenosis associated with metastatic insulinoma presenting as mass lesions

One of the important functions of the liver is glycogen storage. Most processes associated with increased hepatic glycogen, or glycogenoses, are metabolic and affect the entire liver leading to diffuse glycogenosis. We present a case in which the liver contained multiple small pale nodules that on initial assessment were recognized to be composed of glycogenated hepatocytes. Most of the known causes of hepatic glycogenosis were not pertinent to this case. After cutting many deeper levels and obtaining additional sections, small foci of insulinoma were revealed in the center of each of these lesions. The glycogenosis surrounding the foci of insulinoma can be best explained as a local effect of insulin on the hepatocytes, a phenomenon that has been previously described in primate models, but not in human subjects. Here, we report the first case of metastatic insulinoma causing local hepatic glycogenosis.