Challenges with preoperative diagnosis of low/intermediate-grade carcinoma of the parotid gland: single-center study of 112 patients.

BACKGROUND: The malignancy of parotid carcinoma varies, and accurate preoperative assessment of malignancy is important for selecting the appropriate treatment. However, the preoperative diagnosis of low/intermediate-grade carcinoma is difficult, and surgery may sometimes be performed without any prior knowledge of malignancy. METHODS: The results of fine-needle aspiration cytology (FNA), imaging studies (MRI and US), physical examination, and frozen section biopsy (FSB) were evaluated in 112 patients with low/intermediate-grade parotid carcinoma. RESULTS: The result of FNA was benign/inadequate specimen in 44.6% of the patients. In addition, the tumor was diagnosed as benign by MRI/US in 21.4% of the patients and 37.5% had no symptoms/signs of malignancy on physical examination. The rate of misdiagnosis as benign decreased when FNA was combined with imaging and physical findings. However, malignancy could not be diagnosed by FNA and FSB in 12.5% of the patients who were only found to have malignant tumors by the final pathological examination. CONCLUSION: FNA shows a high misdiagnosis rate of malignancy in patients with low/intermediate-grade cancer. Therefore, it is necessary to carefully evaluate the findings of imaging studies and physical examination, and FSB should be conducted if such findings suggest the possibility of malignancy.