Cytologic grading of primary malignant salivary gland tumors: A blinded review by an international panel

Abstract

BACKGROUND: Fine needle aspiration (FNA) is commonly used for the preoperative evaluation of salivary gland tumors.Tumor grade is a key factor influencing clinical management of salivary gland carcinomas (SGCs). To assess the ability to grade nonbasaloid SGCs in FNA specimens, an international panel of cytopathologists convened to review and score SGC cases. METHODS: The study cohort included 61 cases of primary SGC from the pathology archives of 3 tertiary medical centers. Cases from 2005 to 2016 were selected, scanned, and digitized. Nineteen cytopathologists blinded to the histologic diagnosis reviewed the digitized cytology slides and graded them as low, high, or indeterminate. The panelists' results were then compared to the tumor grades based on histopathologic examination of the corresponding resection specimens. RESULTS:All but 2 of the 19 (89.5%) expert panelists review more than 20 salivary gland FNAs per year; 16 (84.2%) of the panelists work at academic medical centers, and 13 (68.4%) have more than 10 years' experience. Participants had an overall accuracy of 89.4% in the grading of SGC cases, with 90.2% and 88.3% for low-and high-grade SGC, respectively. Acinic cell carcinoma and mucoepidermoid carcinoma had the highest degree of accuracy, while epithelial-myoepithelial carcinoma and salivary duct carcinoma had the lowest degree of accuracy. As expected, the intermediate-grade SGC cases showed the greatest variability (high-grade, 42.1%; low-grade, 37.5%, indeterminate, 20.4%). CONCLUSION: This study confirms the high accuracy of cytomorphologic grading of primary SGC by FNA as low-or high-grade. However, caution should be exercised when a grade cannot be confidently assigned. Cancer Cytopathol 2020;128:392-402.

Putting morphology to the test: An established classification scheme reliably stratifies salivary gland cytology by risk of malignancy with substantial interobserver agreement

“…2 Although FNAC generally demonstrates good sensitivity (approximately 70%-80%) and high specificity (>90%) for diagnosing malignancy among patients with neoplastic lesions, these test characteristics have shown wide heterogeneity across institutions. 2,3 Salivary gland FNAC also may distinguish low-grade from high-grade malignancy, 4 which can alter the surgical approach from a limited excision to a radical resection, with the potential for facial nerve sacrifice and ipsilateral neck dissection. 4 However, in the last several years, the interinstitutional variability in salivary gland FNAC performance combined with the less than perfect sensitivity for malignancy has led to increasing interest in a universal risk stratification system for salivary gland FNAC classification.…”

“…2,3 Salivary gland FNAC also may distinguish low-grade from high-grade malignancy, 4 which can alter the surgical approach from a limited excision to a radical resection, with the potential for facial nerve sacrifice and ipsilateral neck dissection. 4 However, in the last several years, the interinstitutional variability in salivary gland FNAC performance combined with the less than perfect sensitivity for malignancy has led to increasing interest in a universal risk stratification system for salivary gland FNAC classification. 5,6 The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was introduced to address these issues, creating a standardized system with which to improve the practicing cytologist's diagnostic approach and better guide subsequent therapeutic interventions.…”

Application of the Milan System for Reporting Salivary Gland Cytopathology: Experience of an academic institution in a tertiary academic medical center

“…Miller et al reported high diagnostic accuracy for MEC (78.7%) and a higher ROM when MEC is included in the differential diagnosis 34 . Johnson et al also reported high diagnostic accuracy for MEC but their study only included neoplastic lesions and the best overall agreement among the panelists was noted with regard to high‐grade lesions 35 . In the current study, the majority of MECs were low grade (10 of 11 cases) and were classified in the indeterminant categories (AUS, SUMP, or suspicious).…”

Fine needle aspiration of salivary gland carcinomas with high‐grade transformation: A multi‐institutional study of 22 cases and review of the literature

“…From a clinical perspective, HGT is known to impart more aggressive biologic behavior and a worse prognosis than conventional low‐ to intermediate‐grade SGC 4,6‐8 . Preoperative recognition of a high‐grade component by fine needle aspiration (FNA) would therefore be useful for patient prognostication as well as for influencing patient management, including presurgical planning 9 . Despite wide recognition of this disease concept, only a few case reports describing the cytological features of SGC with HGT have been published, 10‐17 and comprehensive FNA case series are lacking.…”

“…4,[6][7][8] Preoperative recognition of a high-grade component by fine needle aspiration (FNA) would therefore be useful for patient prognostication as well as for influencing patient management, including presurgical planning. 9 Despite wide recognition of this disease concept, only a few case reports describing the cytological features of SGC with HGT have been published, [10][11][12][13][14][15][16][17] and comprehensive FNA case series are lacking. Using a multi-institutional approach, we describe the clinical and cytomorphologic features of the largest FNA series of SGC with HGT and provide a comprehensive review of the literature.…”