CT features of parotid tumors: an analysis of 133 cases

Objective: Most parotid tumors grow slowly. It is difficult to evaluate their malignancy. This study was to analyze the CT features of parotid tumors.

Methods: CT images of 133 patients with 157 lesions of parotid tumors, confirmed by histopathology, were reviewed. The location, contour, margin, enhancing type, necrosis and liquefaction, and adjacent structure involvement were analyzed.

Results: Among the 157 lesions, 110 (70.1%) were benign tumors, 18 (11.5%) were borderline tumors, and 29 (18.5%) were malignant tumors; 80 (72.7%) benign lesions and 14 (77.8%) borderline lesions located in the superficial lobe, whereas 7 (24.1%) malignant lesions located in the deep lobe and 10 (34.5%) in both the superficial lobe and the deep lobe; 99 (90.0%) benign lesions had sharp margins, 8 (44.4%) borderline lesions had sharp margins and 10 (55.6%) had partly unsharp margins, 10 (34.5%) malignant lesions had partly unsharp margins and 11 (37.9%) had unsharp margins. Most benign lesions were round (68/110, 61.8%) or oval (23/110, 20.9%), while malignant lesions were often irregular (14/29, 48.3%). Eleven lesions, including 2 borderline tumors and 9 malignant tumors, involved the adjacent subcutaneous fat. All the lesions which involved the bed of parotid gland were malignant. No benign tumor involved adjacent structures.

Conclusions: On CT images, a parotid tumor located in the superficial lobe, with a round or oval contour and sharp margin, is more likely to be a benign tumor; otherwise, it might be a malignant tumor.