Three unusual cases of secondary hydatid cysts of the peritoneal cavity of the pig, dog, and cat

Abstract

Extract

Hydatid cysts may be classified as primary cysts when they arise from the hexacanth embryo or as secondary cysts when they arise from scolices. The majority of cysts are primary and follow the swallowing of ova by a suitable intermediate host. Most of them occur in the liver or the lung, but they may also be found in other organs such as the heart, spleen, kidney, bone, muscle, or brain. Secondary cysts, on the other hand, are formed when scolices or occasionally daughter cystsare liberated into the tissues of the same host after the rupture of the primary cyst. Secondary cysts are most frequently seen in the peritoneal cavity after the rupture of an hepatic cyst but they may also occur in other sites such as the pleural or pericardial cavities or they may be metastatic if the scolices are shed into the vascular system. Metastatic cysts may occur in the lung if the ruptured primary cyst is in the liver or the right heart or may be generalized if in the left heart. In such cases, multiple cysts appear almost invariably in the brain and these produce critical symptoms long before those: in other situations.