Diagnostic accuracy of fine needle aspiration cytology for high-grade salivary gland tumors

摘要

Background: Preoperative differentiation between high-grade malignancy and others (benign or low-grade tumors) is more important than differentiation between malignant and benign tumors for surgical planning, treatment outcome, and prognosis in salivary gland tumors. Fine needle aspiration cytology (FNAC) has a relatively low sensitivity for differentiating malignant from benign salivary tumors. However, the diagnostic performance of FNAC has not been studied in predicting high-grade salivary malignancy, which can significantly affect patient care. Methods: Experienced cytopathologists reevaluated the adequate FNAC on 521 salivary gland tumors. The diagnostic performances of FNAC for total malignancy and high-grade malignancy were calculated, and the results were validated in independent 105 cases. In cases of high-grade cancer on FNAC, we recorded the additional diagnostic procedures and the change of surgical extent to decide how FNAC impacts clinical practice. Results: The sensitivity, specificity, and diagnostic accuracy of FNAC in differentiating malignant from benign tumors were 64.2 % (95 % confidence interval 52.3-75.0), 98.4 % (96.5-99.3), and 92.1 % (89.1-94.6). Meanwhile, FNAC predicted high-grade malignancy accurately (94.6 % [80.0-99.5], 99.2 % [97.8-99.7], 98.9 % [97.3-99.6], respectively), a finding reproduced with similar results in the validation set. FNAC indicative of high-grade malignancy added additional imaging assessments in 94.9 %, frozen biopsy samples during surgery (tumor and lymph nodes) in 71.2 %, and changed the extent of surgery in 59.0 %. Conclusions: FNAC has an excellent diagnostic performance in discriminating high-grade salivary cancer, which guides clinical decision and surgical planning in salivary gland tumors.