Pathological Basis Of Ultrasound Imaging Of Parotid Masses And Qualitative Diagnosis

Objective: To analysis the value of ultrasound assessment in diagnosis of parotid swellings and their pathological bases.Methods: 227 cases of parotid gland swelling in 2nd afflicted hospital of Zhejiang University from 1998 to 2003 were collected. These cases with complete case histories included 157 benign tumorsAesions, 51 malignant tumors, 16 non-space occupying lesions, and 3 misdiagnosed lesions. The 208 localized lesions were divided into 4 groups: benign tumors, malignant tumors, cyst lesions and non-neoplastic lesions. The parameters "shape", "boundary" , "intensity level of internal echoes", "distribution of internal echoes," "acoustic enhancement" and "blood signal" were employed to depict the ultra sonogram. The information of location, shape, envelope and character of the lesions were noted according to the operation record. Some pathological slices were observed to validated the difference of the same diagnosed lesion. Ultrasound's capability of detecting localized lesion and of locating swelling were calculated. The distribution of 6 parameters in 4 groups was analyzed. Chi-square test was used for statistic analysis. Results:1 Ultrasound was extremely sensitive in the detection of localized lesions, with the sensitivity 99.0% and the positive predictive value 98.6%.2 Ultrasound was accurate in locating the swellings, with the accurate rate 98.1%, and the specificity of locating the swelling in superficial part is 100%.3 In ultra sonogram, Some Warthin's tumor appeared "net-like" internal echoes, andsome lipoma appeared "feather-like" internal echoes.4 The cyst lesions had much similar ultrasonic appearances.5 Appearances of sonography of swelling had correspondence to their pathological structure.6 There were 4 parameters contributing to differentiate benign tumors and malignant tumors: (1) "boundary" (x2 = 57.100,p=0.000) (2) "acoustic enhancement"= 64.080, p=0.000)(3)"no internal echoes"(x2 = 12.522,p=0.000) (4)"blood signal" (x2 = 36.561, p=0.000) . 1 parameter contributed to differentiate benign tumors and non-neoplastic lesions: "acoustic attenuation" (Fisher's Exact Test, p=0.000) . NO parameter contributed to differentiate malignant tumors and non-neoplastic lesions. Conclusion: Ultrasound is extremely sensitive in detecting localized lesion and is accurate in localizing lesions into the parotid gland. It is readily for ultrasound to recognize the cyst lesions. In typical ultrasonic appearance, Warthin's tumor and lipoma can be identified specially. It is impossible to identify the pathologic structure according to the ultra sonogram; however, it is possible to differentiate one group from the other according to the distribution of parameters clinically, in terms of certain combinations.