 Polycystic liver disease PLD is the most common extra-renal manifestation in ADPKD, present in 90 of ADPKD patients by age 30. Liver cysts in ADPKD originate from biliary micro-hamartoma or focal proliferations of biliary ductules and from peribiliary glands. Excessive proliferation of biliary epithelial cells, combined with neovascularization, altered cell-extracellular matrix ECM interactionECM remodeling and cAMP-mediated fluid secretion, is required for the development and expansion of PLD liver cysts. 