[Primary hydatid cyst of the parotid gland]

Introduction: The hydatid cyst is an anthropozoonosis due to the development of the Echinococcus granulosus tapeworm larva in humans. Its intraparotid localization is extremely rare.

Clinical case: A 10-year-old-male patient was admitted for an isolated renitent swelling of the left parotid region having grown for several months. Cervical ultrasonography revealed a left parotid cystic mass, characterized by a double wall, and a small daughter cyst. The CT-scan typically showed the absence of enhancement after iodine contrast medium injection. The imaging-based diagnosis of a hydatid cyst was supported by positive hydatid serology, and confirmed by histological analysis of the cyst. No other hydatid location was found (chest and abdominal).

Discussion: In spite of its rarity, hydatid cyst can be a diagnosis in case of parotid cystic masses. Ultrasonography is the first examination to be performed; it must be completed by CT-scan or even better by MRI. Once the diagnosis of hydatid cyst is confirmed, a chest radiograph and an abdominal ultrasonography should be performed, to screen for other localizations. Surgical resection is the gold standard treatment.