[High serum alkaline phosphatase level revealing a liver adenoma]

A 25-year-old woman had a high serum level of alkaline phosphatase activity (2571 UI/L). Serum levels of transaminases, gamma glutamyl transferase and bilirubin were normal. Abdominal ultrasonography revealed a tumor nodule in the right liver lobe. There was no evidence of biliary obstruction. The serum activity of alkaline phosphatase returned to normal after surgical removal of the liver tumor. Histologic examination showed that the tumor was a liver adenoma with no evidence of degeneration. The adenoma cells reacted strongly positive to alkaline phosphatase by histochemical staining. The production of hepatic and biliary type alkaline phosphatase by the tumor is the most likely mechanism for the high serum levels observed in this patient.