The differential diagnosis of cystic cervical masses includes benign lesions, such as second branchial cleft cysts, and malignant metastatic tumors. The incidence of human papillomavirus-related oropharyngeal cancer is increasing, and it often presents with a cystic lymph node metastasis. Therefore, in some cases, malignant metastasis is diagnosed after the resection of a cystic cervical cyst diagnosed initially as a benign tumor.
We report a case of human papillomavirus-related oropharyngeal cancer that was diagnosed after the resection of a second branchial cleft cyst. A 40-year-old woman visited our hospital with the chief complaint of a cervical mass. The mass was resected and postoperative histopathology revealed a cystic cervical cyst. Twenty months later, the cystic cervical mass recurred and was treated by resection of the cystic tumor as well as dissection of the lymph nodes around the tumor. The postoperative histopathological diagnosis was a second branchial cleft cyst and there was no evidence of malignancy. After another 30 months, the cystic cervical mass recurred yet again, and about two more months later, it began to grow rapidly in size; MRI revealed a tonsillar tumor. Biopsy confirmed the diagnosis of p16-positive oropharyngeal cancer. A retrospective histologic review of the previously resected cystic lesions demonstrated p16 positivity in both the first and second resection specimens. Therefore, they were also assumed to have been lymph node metastases from the p16-positive oropharyngeal cancer. The patient received concurrent chemoradiotherapy and the tumor disappeared. There was no evidence of recurrence at the one-year follow up. Regardless of the history, the possibility of cystic metastatic lymph node should always be kept in mind in patients presenting with cervical cystic masses, and imaging examinations such as CT and MRI including the pharynx should be performed.
