What causes hepatic cysts?

From the Guidelines

Liver cysts are primarily caused by abnormal fetal ductal plate maturation, leading to the formation of fluid-filled lesions lined by a single cell layer, as stated in the EASL clinical practice guidelines on the management of cystic liver diseases 1. The pathogenesis of cysts involves ductal plate malformation, where the ductal plate disconnects from the biliary tree and progresses into cystic structures.

• The ductal plate is a double cylinder of hepatoblasts encircling portal vein branches that provides the scaffold for bile duct development.
• Cysts arise as a result of ductal plate malformation when the ductal plate disconnects from the biliary tree and progresses into cystic structures.
• Epithelial cells in the cyst retain a secretory function and fluid production generates a positive luminal pressure that contributes to the cyst’s architecture. Other causes of liver cysts include:
• Congenital liver cysts, which are present at birth and often part of polycystic liver disease, an inherited condition where multiple cysts form throughout the liver.
• Simple liver cysts that develop spontaneously.
• Parasitic infections, particularly Echinococcus, causing hydatid cysts.
• Cysts that form as a complication of liver diseases like cirrhosis.
• Trauma to the liver can also lead to cyst formation.
• Bile duct abnormalities, such as in Caroli disease, can also lead to liver cyst formation, as mentioned in the EASL clinical practice guidelines on the management of cystic liver diseases 1. The exact mechanism involves abnormal tissue development or fluid accumulation within isolated compartments of the liver, and while genetics plays a significant role in congenital and polycystic liver disease, environmental factors may contribute to the development of other types of liver cysts, as supported by the guidelines 1.

From the Research

Causes of Liver Cysts

• Liver cysts can be caused by various factors, including congenital conditions, post-traumatic events, benign or malignant tumors, and infectious pathologies 2, 3.
• Congenital cystic lesions of the bile ducts, such as Caroli disease, choledochal cysts, and autosomal dominant polycystic liver disease, can also cause liver cysts 4.
• Simple cysts are mainly congenital cysts, but also occur in polycystic liver disease, while complex cysts include mucinous neoplasms, echinococcal cysts, hemorrhagic cysts, cystic hepatocellular carcinoma, and other rare lesions 3.

Types of Liver Cysts

• Simple cysts: mainly congenital cysts, but also occur in polycystic liver disease 3.
• Complex cysts: include mucinous neoplasms, echinococcal cysts, hemorrhagic cysts, cystic hepatocellular carcinoma, and other rare lesions 3.
• Congenital cystic lesions of the bile ducts: include Caroli disease, choledochal cysts, autosomal dominant polycystic liver disease, congenital hepatic fibrosis, and biliary hamartomas 4.

Diagnosis and Characterization

• Imaging modalities such as conventional ultrasound, computed tomography, magnetic resonance imaging, or contrast-enhanced ultrasound can be used to characterize and diagnose liver cysts 2, 3.
• Ultrasound is typically the first-line imaging modality, whereas more advanced imaging can help narrow down the specific lesion 3.
• Features such as septae, mural consistency, calcifications, and quality of cystic fluid can help identify liver cysts and differentiate between simple and complex cysts 3.