Parasitic Hepatic Cysts

Parasitic cysts of the liver are mainly echinococcal cysts due to infection caused by 1 of 2 species of Echinococcus: E granulosus (cystic echinococcosis) or E multilocularis (alveolar echinococcosis).

Clinical features: Manifestations occur in a varying proportion (up to 80%) of the infected individuals and depend on the location of the cysts, their size, the degree of development and viability of the parasite, and occurrence of complications. In most cases (>80%) echinococcosis manifests as a single cyst located in the liver, most frequently in the right lobe. In the case of alveolar echinococcosis, apart from the primary cyst located in the liver, in ~30% of patients extrahepatic lesions develop as a consequence of infiltration or dissemination to distant sites.

Diagnosis: Imaging findings raise suspicion: see Table 1 in Hepatic Tumors; the etiologic factor should be identified.

Treatment: Surgical removal of cysts is the treatment of choice, especially in alveolar echinococcosis. Liver resection or cystopericystectomy (excision of a cyst without opening the lumen) is performed. In echinococcosis, transdermal therapy in specialist centers is also acceptable. Liver transplant can be performed in patients with alveolar echinococcosis who have very advanced multifocal lesions within the liver parenchyma, a priori unresectable, or in whom disease progression has led to liver failure.