Prevalence of cystic metastases in a consecutive cohort of surgically removed branchial cleft cysts

BACKGROUND: Solitary cystic lesion of the neck may often be the only initial presenting symptom for branchial cleft cysts and cystic metastases. AIMS/OBJECTIVES: To analyse the malignancy rate detected in patients undergoing surgical treatment for lateral branchial cleft cyst. MATERIAL AND METHODS: The records of all patients with surgical procedure code ENB40 (Excision of lateral branchial cleft cyst- or fistula) between 2003 and 2019 were reviewed. After excluding 150 patients, 436 patients were included for final analysis. Re-evaluation of the cytology including HPV-analysis was performed in those who had a malignant cyst. RESULTS: Cystic metastases were demonstrated histologically after surgical excision in 13 patients (3%). In patients over 18 years of age, the prevalence of cystic metastasis regardless of the primary tumour type was 3.3%. CONCLUSION AND SIGNIFICANCE: When the investigation protocol for solitary cystic lesions of the neck is followed, the negative predictive value for malignancy is 97%. All adult patients with a cytologic verified diagnosis of branchial cyst should be examined with HPV-analysis of the cystic sample before excision of the cyst. Failure of predicting a malignancy is often associated with cytology of poor cellularity which may be improved by more frequent use of ultrasound guided fine-needle aspiration cytology (FNAC).