Background: The recently described Milan system provides a unified way of categorizing salivary gland fine-needle aspiration (FNA) cytology. We aim to use this system to stratify risk of malignancy in parotid FNAs.
Methods: In this retrospective case series, 376 FNAs were preoperatively performed for 573 parotidectomies over 14 years.
Results: Risk of malignancy on FNA is as follows: nondiagnostic 14.5%, non-neoplastic 26.7%, atypia of undetermined significance 29.3%, benign neoplasm 2.7%, neoplasm of uncertain malignant potential 19.1%, suspicious for malignancy 87.5%, and malignant 100%. The specific diagnoses of pleomorphic adenoma and Warthin tumor on FNA have high positive predictive value of 97.5% and 96.6%, respectively. Multivariate regression associates smaller size of lesion with a nondiagnostic or indeterminate result. Seniority of operator is associated with a lower likelihood of a nondiagnostic result.
Conclusions: This large Asian series validates the Milan system as a valuable tool in stratifying malignancy risk of parotid FNAs.
Keywords: cytology; fine-needle aspiration; parotid gland neoplasms; salivary gland neoplasms.
© 2019 Wiley Periodicals, Inc.