Analysis on the CT findings of benign and malignant parotid tumors

Background and purpose:Parotid gland is rich in fat and has obvious contrast with bone and muscle in CT image.The preoperative examination of CT could help to evaluate the scale of tumor invasion and the relationship between tumor and normal tissues so that the proper therapy could be properly designed.The purpose of this study was to evaluate the roles of computer tomography(CT)in differential diagnosis of benign and malignant parotid tumors and to improve the diagnostic accuracy.Methods:CT images of 17 patients with benign parotid tumors and 15 patients with malignant parotid tumors proved by pathology were analyzed retrospectively.All patients underwent CT contrast-enhanced examination preoperatively.Images of all patients were retrospectively reviewed by two experienced radiologists in the diagnosis of head and neck tumors.Results:14 of 17 cases of benign tumors had round shapes and 9 of 15 cases of malignant tumors exhibited lobular or irregular masses(P0.05);Small sheet low density could be seen in six benign tumors(6/17)but none in malignant tumors(0/15)(P0.05);The edges of benign tumors(13/17) were clear but that of malignant tumors(11/15)were blurry(P0.05);The borderline of two benign tumors(2/17) and sternocleidomastoid or masseter were unclear but most malignant tumors(9/15)invaded sternocleidomastoid or masseter(P0.01);None of benign tumors had increscent lymph node and the invasion of nerve and vein,six cases of fifteen malignant tumors had increscent lymph node(P0.01),and four cases had the invasion of nerve and vein(P0.05).Conclusions:The margin,shape,density and the invasion of sternocleidomastoid or masseter of tumors are the important factors for distinguishing benign from malignant parotid tumors.Increscent lymph node and the invasion of nerve and vein by tumor are the diagnostic features of malignant parotid tumors.CT examination can exactly evaluate most of the benign and malignant parotid tumors.