The impact of FNAC in the management of salivary gland lesions: Institutional experiences leading to a risk‐based classification scheme

Abstract

BACKGROUND: Fine-needle aspiration cytology (FNAC) has proven its value as an essential step in the diagnosis of salivary gland lesions. Although the majority of salivary gland lesions, especially those that are common and benign, can be diagnosed with ease on FNAC, limited cellularity and morphologic lesion heterogeneity can pose diagnostic challenges and lead to false-positive and false-negative diagnoses. This study presents the institutional experience of FNAC of salivary gland lesions from 2 academic centers. METHODS: A retrospective analysis was conducted on 1729 salivary gland FNAC specimens that were diagnosed over an 8-year period from January 2008 to March 2015. All samples were processed either with liquid-based cytology alone or in combination with air-dried, Diff-Quik-stained or alcohol-fixed, Papanicolaou-stained smears. RESULTS: Surgical excision was performed in 709 of 1749 FNACs (41%) that were diagnosed as nondiagnostic/inadequate (n 5 29), benign (n 5 111), neoplasm (n 5 453), atypical (n 5 15), suspicious for malignancy (n 5 28), and malignant (n 5 73). The overall concordance between cytologic and histologic diagnoses was 92.2%, with 91.8% concordance in the benign category and 89.5% concordance in cases diagnosed as suspicious for malignancy and malignant. The most frequent benign and malignant lesions were pleomorphic adenoma and squamous cell carcinoma, respectively. There were 46 false-negative and 13 false-positive results, leading to an overall specificity of 97.6% and diagnostic accuracy of 91.3%. CONCLUSIONS: FNAC is a reliable diagnostic modality for the diagnosis and management of salivary gland lesions based on its high specificity and diagnostic accuracy. Cancer Cytopathol 2016;124:388-96. V C 2016 American Cancer Society.

Risk of high‐grade malignancy in parotid gland tumors as classified by the Milan System for Reporting Salivary Gland Cytopathology

“…The Milan System was introduced in 2017 for standardizing FNAC reports . Several studies have proven its efficacy and determined the risk of malignancies according to each category of the Milan System …”

A pattern‐based risk‐stratification scheme for salivary gland cytology: A multi‐institutional, interobserver variability study to determine applicability

“…In a retrospective multi institutional international study, it was shown that separation of salivary gland aspirates into primary categories of neoplasm, atypical, suspicious for malignancy and malignant resulted in a stratified risk of malignancy (ROM) (respective ROM – 6%, 53%, 79% and 100%). 8 More recently, it was shown that designation of salivary aspirates as suspicious for malignancy had a similarly high ROM (84.2%) with no statistically significant difference between five international tertiary medical centers. 9 In contrast, another abstract by the same authors reported a wide range in the ROM for salivary gland aspirates designated atypical (mean ROM 62.99%, range 0–73.08%).…”

The role of the Milan System for Reporting Salivary Gland Cytopathology: A 5‐year institutional experience

“…In the majority of cases, the salivary gland lesions are easily accessible for FNA, either superficially by palpation or by USG. The technique is minimally invasive and well tolerated by patients without significant complications, and is a cost‐effective diagnostic tool with a high sensitivity and specificity of approximately 54% to 98% and 88% to 98%, respectively . FNA plays a key role in guiding clinical management and provides useful information such as distinguishing between a neoplastic and a non‐neoplastic lesion, ascertaining whether a lesion is benign or malignant, and, last, providing prognostic information and a sample for ancillary testing such as molecular studies …”