Diagnostic Accuracy of FNAC and Ultrasonography in Salivary Gland Lesions in Comparison with Histopathology

Abstract

Introduction: Modern era demands for early and accurate diagnosis. Fine Needle Aspiration Cytology (FNAC) and Ultrasonography (USG) are two such diagnostic modalities which have gained importance in recent years due to their rapid, repeatable and precision properties. Aim: To study the accuracy of FNAC and USG in diagnosing salivary gland lesions in comparison with histopathology and to study the expression of p63 and Cytokeratin 7 (CK7) Immunohistochemical (IHC) markers in malignant salivary gland tumours. Materials and Methods: A cross-sectional study was conducted on 106 cases who presented with salivary gland lesions possessing USG reports and underwent FNAC and surgical specimens received in Cytopathology and Histopathology Department, Government Medical College Thiruvananthapuram, Kerala, India during one year period (February 2017-January 2018). In each case FNAC was performed and slides were stained with Papanicolaou and Giemsa, surgical specimens were grossed, histopathological features studied under microscope and tumours classified according to World Health Organisation (WHO) Classification of Salivary gland Tumours 2017. Diagnosis on USG and FNAC were compared with histopathological diagnosis. Sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV), diagnostic accuracy, concordance and discordance was calculated by Statistical Package for the Social Sciences (SPSS) software 24.0 version. p63 and CK7 IHC markers were done only in malignant salivary gland tumours. Results: In the present study majority of lesions i.e. 82 cases (77.4%) were seen predominantly in parotid gland and pleomorphic adenoma was the most commonest lesion and neoplasm overall with 50 cases (47.2%). Most common malignant neoplasm was mucoepidermoid carcinoma (four cases, 3.8%). USG and FNAC had high diagnostic accuracy of 89.6% and 97.2% in comparison to histopathology in diagnosing salivary gland lesions. Conclusion: High sensitivity and specificity of USG and FNAC makes them most acclaimed preoperative diagnostic modality for salivary gland lesions, but histopathology remains gold standard. Subtyping of malignant and cystic lesions were difficult in USG and cytology