Orbital hydatid cyst.

Hydatid cysts rarely appear isolated in the orbital cavity without involvement of other organs. Most of these are situated in the superolateral and superomedial angles of the orbit. Inferiorly located cysts are very uncommon. The authors report a case of a primary hydatid cyst of the orbit with inferiolateral localization. The cyst was enucleated surgically via a rhinotomy approach. This case was considered as a primary infection, because there was no previous history of hydatid disease and no findings of liver and lung cysts on radiological examination. Physicians should include orbital hydatid cyst in the differential diagnosis of unilateral proptosis. To avoid complications that might occur during surgery, the cyst can be easily removed using a gentile enucleation technique.