Primary hydatid cyst of the parapharyngeal space: a rare head and neck presentation.

Hydatid disease, caused by Echinococcus granulosus, most commonly affects the liver and lungs. Involvement of the head and neck region, particularly the parapharyngeal space, is extremely rare and poses a diagnostic challenge. We report the case of a 13-year-old girl from an endemic area who presented with a painless, rapidly enlarging mass in the right parapharyngeal space, developing over 6 months. Clinical examination revealed a firm, non-tender, transilluminant swelling with intraoral bulging. Computed tomography demonstrated a well-defined cystic lesion in the right parapharyngeal space. The cyst was completely excised via a transcervical approach. Histopathological examination confirmed hydatid cyst, revealing laminated membranes, protoscolices, and daughter cysts. The postoperative course was uneventful, and albendazole was prescribed for two months to prevent recurrence. This case emphasizes considering hydatid disease in the differential diagnosis of cystic neck masses in patients from endemic regions, even in unusual locations.