Abstract

Hydatidosis, caused by the larval stage of Echinococcus granulosus, is the most frequently encountered type of hydatid disease in humans. Due to the close association that exists between sheep and dogs and humans, it is endemic to many parts of the world, particularly the Mediterranean countries including Turkey, the Middle East, South America, Africa, New Zealand, the Russian Federation, Central Asia, and Australia [1]. The adult tapeworm, a true hermaphrodite, lives in the intestine of the definitive hosts. Its terminal segment, which contains 500 to 800 eggs, is released into the intestinal tract of a dog and is expelled in dog faeces. The intermediate host, sheep or human, swallows the ovum, and the outer shell of the ovum dissolves in the duodenum, liberating an embryo. If the uncooked viscera of sheep are eaten by dogs, protoscolices develop into adult tapeworms, and the life cycle of the parasite is completed. In the intermediate host, the embryos enter the portal circulation in the intestines, and most of them are caught in the liver, whereas some reach the pulmonary arteries. Those entrapped within the lung parenchyma develop cysts in the lungs, whereas some may even pass through the lungs and reach the systemic circulation. The most frequently involved organ is the liver (65%) because most of the embryos are trapped within it. Other involved sites are the lungs (25%), and less frequently the spleen, kidneys, heart, bone, and central nervous system. The occurrence of hydatid cysts in the head and neck is rare even in countries where echinococcus infestation is endemic. Hydatid cysts involving the parotid region, parapharyngeal space, infratemporal fossa, maxillary sinus, and pterygopalatine fossa [2, 3] as well as the anterior or posterolateral cervical region 1 have been reported in the literature.