Ultrasonographic features of parathyroid carcinoma

Although several authors have reported single cases illustrative of some ul trasonographic characteristic of parathyroid carcinoma, the value of ultras onography for diagnosing this entity remains to be determined. The purpose of our study was to investigate the ultrasonographic features of parathyroi d carcinoma in a large number of cases. We assessed the shape, contour, ech ogenicity, and depth-width (DW) ratio of 16 parathyroid carcinomas and 61 p arathyroid adenomas. UItrasonography showed that parathyroid carcinomas ten d to be large, inhomogeneous, hypoechoic masses with lobulated contours. In contrast, parathyroid adenomas were small, homogeneous, hypoechoic masses with smooth borders. The mean (range) DW ratios for parathyroid carcinomas were 1.21 (0.91-2.5) and 0.64 (0.33-1.47) for adenomas; the difference was statistically significant (p <0.0001). The DW ratio was <greater than or eq ual to>1 in 15 (94%) of the 16 cases of carcinoma, whereas only 3 (5%) of t he 61 adenomas had a similar ratio. Ultrasonographic examination is useful not only for preoperative localization but also for differentiating parathy roid carcinoma from adenoma. Parathyroid tumors with irregular margins, inh omogeneous echogenicity, and a DW ratio greater than or equal to1 are likel y to be malignant.