Many case reports describing various benign and malignant disease entities diagnosed in cystic parotid gland lesions by fine-needle aspiration (FNA) exist in the literature. Very few studies, however, discuss the efficacy and the diagnostic difficulties of FNA cytology in such lesions. The authors report a 5-year institutional experience with FNA cytology of cystic parotid gland lesions and address the accuracy of the procedure and avoidance of diagnostic pitfalls.
A retrospective review of 46 cases in which patients clinically presented with cystic parotid gland lesions was done from a total of 221 parotid FNAs performed over a 5-year period at the University of Pennsylvania Medical Center. The clinical features, cytology, and follow-up surgical pathology were reviewed to determine diagnostic accuracy and highlight potential pitfalls.
Based on subsequent surgical excision in 29 of the 46 cases of cystic parotid gland lesions, a diagnostic accuracy rate of 83% was obtained for FNA. Approximately 20% (9 of 46 cases) were found to be clinically significant tumors and included 4 mucoepidermoid and 1 adenocarcinoma (NOS), 3 benign mixed tumors, and 1 metastatic melanoma. Three major factors were implicated as diagnostic pitfalls in our series: 1) failure to obtain critical clinical information, 2) overinterpretation of paucicellular specimens, and 3) failure to realize that certain tumors generally perceived as solid masses can present clinically as cystic lesions.
FNA cytology is a valuable tool in the primary diagnosis and management of cystic parotid gland lesions. The diagnostic accuracy of this procedure can be significantly improved by acquiring a detailed clinical history, obtaining an adequate cellular specimen, and having knowledge of the variety and frequencies of possible diagnostic entities that may present as cystic parotid gland lesions.