Parotidectomy specimens: cytological and histological correlation

Abstract

Background: There are few descriptive studies from South Africa of parotid gland tumours. This is a descriptive study of parotid pathology managed surgically, and to ascertain the accuracy and concordance of preoperative cytological diagnosis compared with final pathology. Methods: A retrospective chart review of all parotidectomies performed between January 2016 and September 2024 was done. Incomplete and duplicate files were excluded. Results: A total of 179 specimens were included and confirmed benign tumours in 125 (69.83%), malignant tumours in 51 (28.749%), and non-neoplastic disease in 3 (1.68%). Pleomorphic adenoma was the most common benign tumour accounting for 38.07% (67/176), while squamous cell carcinoma was the most common malignant tumour representing 5.68% (10/176). Of the 179 parotidectomy cases, a 158 had at least one fine needle aspiration biopsy (FNAB) performed. A further 16 patients had other diagnostic tests and were excluded. The remaining 142 cases had a parotid FNAB as the only preoperative investigation. In 113 of these 142 cases FNAB results could be correlated with benign or malignant final histology results. The sensitivity and specificity for identifying malignant tumours were 60% and 96.77% respectively, with an overall accuracy of 90.27%. Our concordance rate for malignant tumours was 80% and 91.84% for benign tumours. Conclusion: The pattern of parotid pathology is consistent with previous regional data. FNAB is reliable for identifying benign tumours but less sensitive for malignancy. Where preoperative histology will influence management, core needle biopsy should be considered, rather than repeating FNAB which provides limited additional value.