Large First Branchial Cyst Extending into the Parapharyngeal Space: A Case Report.

Cystic diseases of the salivary gland include mucous cysts and plunging ranula; cysts in the parotid region are rare. In this report, we describe a case of a first branchial cyst in the parotid region. The cyst extended into the parapharyngeal space and was repeatedly infected. The patient was a 35-year-old woman who presented to our hospital with a mass on the left lower ear. Imaging findings revealed a cystic lesion in the parotid region that extended to the parapharyngeal space. A yellowish slurry was aspirated on a percutaneous fine-needle aspiration biopsy. Cytology revealed a class II tumor. The patient initially showed signs of infection and was treated with intravenous antimicrobial agents. After the infectious inflammation had resolved, surgery was performed to resect the cyst. The infection did not recur postoperatively. A large first branchial cyst extending into the parapharyngeal space, which communicates with Stensen's duct, is rare. Care must be taken during surgery because of the complicated positional relationship between the first branchial cyst, parotid gland, and facial nerve.