ABSTRACT
The pericyst, initially composed of very thin connective lamina, subsequently tends to become thicker (up to 1 cm or more), sclerose, and calcify. The process of cyst expansion causes compression of hepatic parenchymal structures, in turn engulfed into the pericyst. Large vessels are compressed and displaced while remaining, however, patent for a long time. Similarly, bile ducts remain patent and may open into the pericyst, between it, and the parasite wall. This phenomenon occurs frequently, unlike the rare frank rupture of the cyst with effusion of the cyst contents into a large duct and the main bile duct. This is of the utmost importance for surgery, since on the one hand its appearance causes major changes in the cyst and pericyst development, and on the other it favors the development of postoperative complications such as biliary fistulas. Bile filtration in the virtual interstitium between the pericyst and the chitinous membrane can form a perivesicular biloma with loss of direct contact of the cyst with the pericyst, a decrease in the mother cyst pressure and membrane rupture. At the same time, the appearance of bile is preliminary to cyst infection.
