BACKGROUND: The purpose of this study was to prepare the ultrasonographic diagnostic criteria on parotid tumors for preoperative differentiation of superficial and deep tumors. METHODS: We evaluated 154 patients with a benign parotid tumor who underwent surgery. The minimum thickness of normal parotid gland tissue between the parotideomasseteric fascia and tumor (minimum fascia-tumor distance [MFTD]) was measured on preoperative ultrasonography and compared among tumors at different locations, and the optimum cutoff value to differentiate a deep tumor was identified. RESULTS: The MFTD showed significant differences between superficial and deep tumors and between inferior pole and deep tumors. The sensitivity, specificity, and accuracy of an MFTD ≥3 mm for the differentiation of deep tumors were 85%, 91%, and 89%. CONCLUSION: A tumor with an MFTD ≥3 mm on preoperative ultrasonography is very likely to be a deep tumor based on a new differentiation method for deep parotid tumors considering those present at other locations.
BACKGROUND: The purpose of this study was to prepare the ultrasonographic diagnostic criteria on parotid tumors for preoperative differentiation of superficial and deep tumors. METHODS: We evaluated 154 patients with a benign parotid tumor who underwent surgery. The minimum thickness of normal parotid gland tissue between the parotideomasseteric fascia and tumor (minimum fascia-tumor distance [MFTD]) was measured on preoperative ultrasonography and compared among tumors at different locations, and the optimum cutoff value to differentiate a deep tumor was identified. RESULTS: The MFTD showed significant differences between superficial and deep tumors and between inferior pole and deep tumors. The sensitivity, specificity, and accuracy of an MFTD ≥3 mm for the differentiation of deep tumors were 85%, 91%, and 89%. CONCLUSION: A tumor with an MFTD ≥3 mm on preoperative ultrasonography is very likely to be a deep tumor based on a new differentiation method for deep parotid tumors considering those present at other locations.