Tehran University of Medical Sciences Case Reports in Clinical Practice 2538-2683 4 4 2020 04 30 115 118 Shima Hajibegloo Otorhinolaryngology Research Center, Tehran University of Medical Sciences, Tehran, Iran. Farrokh Heidari Otorhinolaryngology Research Center, Tehran University of Medical Sciences, Tehran, Iran. Amirhossein Yadegar Otorhinolaryngology Research Center, Tehran University of Medical Sciences, Tehran, Iran. Firouzeh Heidari Otorhinolaryngology Research Center, Tehran University of Medical Sciences, Tehran, Iran. Ebrahim Karimi Otorhinolaryngology Research Center, Tehran University of Medical Sciences, Tehran, Iran. Keyvan Aghazadeh Otorhinolaryngology Research Center, Tehran University of Medical Sciences, Tehran, Iran. 2019 05 09 2019 07 28 Background: Hydatid cyst is a zoonotic disease due to the infection with the larvae of Echinococcus granulosus. The liver and lungs (80%) are the main organs involved and rarely head and neck. Case Presentation: A 47-year-old Iranian man presented to our center complaining of sublingual inflammation for 8 months. Sonography revealed a cystic lesion of 4×5×6 cm within the tongue. CT-scan showed a well-defined and hypodense mass in the floor of the mouth. Cyst resection was performed with the probability of ranula. Pathology was suggestive of hydatid cyst. Further workups revealed liver involvement. Therefore, he was treated with albendazole for 2 months. Conclusion: The hydatid cyst in the head and neck is rare and the involvement of sublingual gland is extremely rare. However, in endemic areas, hydatid cyst should be considered in the differential diagnosis of head and neck masses. https://crcp.tums.ac.ir/index.php/crcp/article/view/269 https://crcp.tums.ac.ir/index.php/crcp/article/download/269/332