The Liver and Polycystic Kidney Disease

ABSTRACT

The hereditary forms of polycystic kidney disease (PKD) include a wide range of heterogeneous diseases of great clinical importance, of which autosomal dominant PKD (ADPKD) and autosomal recessive PKD (ARPKD) are the main forms. ADPKD is a multifactorial disorder characterized by bilateral renal cysts and usually affects adult patients. Liver cysts are the most common extrarenal manifestations of ADPKD and are often incidental findings and clinically insignificant. In contrast, ARPKD is a severe, typically early-onset form of renal cystic disease. ARPKD patients may present with clinically significant congenital hepatic fibrosis, with portal hypertension, requiring close monitoring, surgical shunting procedures, and kidney and/or liver transplantation. ARPKD is also related to Caroli's disease, a rare autosomal recessive congenital syndrome characterized by multiple saccular dilatations of intrahepatic bile ducts, with predisposition to gallstones, cholangitis and renal cysts. Simple hepatic cysts can also arise from excessive proliferation and dilatation of the bile ducts and peribiliary glands, which are rare in children but their frequency increases with age. The cystic liver epithelial cells have specific receptors, cytokines and growth factors that stimulate and promote cell proliferation and cyst formation. In general, hepatocellular function remains relatively preserved in this group of liver diseases, but may result in complications due to mass effects. The pathogenic sequence and genetic profile of PKD-associated liver cyst formation and progression is under extensive investigation. Therapeutic strategies to prevent and retard renal and liver cyst growth should be available in the near future.