Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 55 8 2017 10 07 530 532 EN Masoud Fallahi Motlagh Department of Oral and Maxillofacial Surgery, Urmia University of Medical Sciences, Urmia, Iran. Hamid Janghi Aghdam Department of Neurosurgery, Azarbayjan Hospital, Urmia, Iran. Behzad Fallahi Motlagh Department of Ophthalmology, Tabriz University of Medical Sciences, Tabriz, Iran. 2016 01 02 2016 10 31 Hydatid cyst is a rare parasitic infection that involved all organs. It caused by the larval stage of Echinococcus tapeworms. Hydatid cyst of the head and neck is a very rare condition, even in areas where Echinococcus infestation is endemic. Orbital hydatid cyst is extremely rare and accounts for less than 1% of all hydatid cysts. Herein a 24-year-old man with primary orbital hydatid cyst is introduced. He complained from proptosis and diplopia. MRI images revealed a lesion with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, which displaced the optic nerve inferiorly and the globe inferolateral. The cyst was enucleated via frontotemporal craniotomy and superior orbitotomy approach. Histopathological examination of the fluid confirmed the diagnosis of hydatid cyst. Treatment of the orbital hydatid cyst is surgical excision followed by the systemic use of albendazole. https://acta.tums.ac.ir/index.php/acta/article/view/5323 https://acta.tums.ac.ir/index.php/acta/article/download/5323/4979