Liver involvement in genetic and metabolic disorders may result in intrahepatic accumulation of specific precursors or byproducts, which have distinctive features on light microscopy. The "polyglucosan disorders" are diseases in which polyglucosan (abnormal glycogen with decreased branching) is formed and deposited in various tissues because of decreased or absent glycogen branching enzyme activity. These disorders include Lafora disease (myoclonus epilepsy) and type IV glycogen storage disease. Polyglucosan deposits in both conditions result in ground-glass hepatocellular inclusions resembling those seen in chronic hepatitis B virus infection. In the present report, we describe a case of the rare, adulthood form of glycogen branching enzyme deficiency, adult polyglucosan body disease (APBD), in which abnormal serum liver tests prompted a liver biopsy. The pathologic findings of periportal ground-glass hepatocellular inclusions, mild chronic portal inflammation, and periportal fibrosis are not well described in APBD, but resemble the chronic changes that have been reported in Lafora disease. The differential diagnosis of ground-glass hepatocytes and the genetic basis of APBD are discussed.