Objective: The purpose of this study was to evaluate the accuracy of sonographically guided core biopsy in the evaluation of parotid masses.
Subjects and methods: Between 1998 and 2004, 135 patients consecutively presenting with a parotid mass were prospectively enrolled into this study. A single operator performed initial diagnostic sonography and then sonographically guided core biopsy using local anesthesia. Biopsy was performed with an 18- or 20-gauge needle and a spring-loaded biopsy gun with a mean of two passes per patient. Outcome measures were accuracy, sensitivity, specificity, and predictive values of sonographically guided core biopsy compared with the final pathologic diagnosis in the surgical group. In the nonsurgical group, final diagnosis was established on the basis of histologic findings after adequate core biopsy and clinical follow-up.
Results: All sonographically guided core biopsy specimens were considered satisfactory for histologic evaluation. Overall there were 71 benign tumors, 35 malignant tumors, and 29 miscellaneous, nonneoplastic lesions. In 76 (56%) of the 135 patients who underwent surgery, sonographically guided core biopsy and surgical histologic findings were correlated for 74 patients. In two cases sonographically guided core biopsy and surgical histologic findings did not correlate. In one case, the sonographically guided core biopsy finding was mucoepidermoid carcinoma, but the final diagnosis was squamous cell carcinoma. In the other case, the finding at sonographically guided core biopsy was squamous cell carcinoma, but the final diagnosis was mucoepidermoid carcinoma. The treatment of these patients was not affected. Fifty-nine (44%) of the 135 patients avoided surgery. In differentiation of benign from malignant disease, sonographically guided core biopsy had a sensitivity, specificity, and diagnostic accuracy of 100%. Sonographically guided core biopsy also had positive and negative predictive values of 100% in the diagnosis of malignancy. There were no significant complications of sonographically guided core biopsy.
Conclusion: Sonographically guided core biopsy is a highly accurate technique for evaluation of parotid lesions and can be safely performed as an outpatient procedure. Sonographically guided core biopsy has potential advantages over fine-needle aspiration cytologic examination, particularly in the typing and grading of lymphoma and carcinoma and in improved differentiation of reactive nodal hyperplasia from lymphoma. The use of sonographically guided core biopsy may help reduce the need for surgical biopsy and facilitates prompt referral to the appropriate clinical team.