Multicentricity of Papillary Thyroid Carcinoma in Contralateral Lobe: A comparison of preoperative ultrasonographic findings with those of postoperative histopathologic examination

ABSTRACT

PURPOSE: Total thyroidectomy can be recommended for patients with bilateral thyroid cancer. Sometimes, it is difficult to preoperatively detect multicentric foci in the contralateral lobe. The aim of this retrospective study is to determine the incidence of multicentricity in the contralateral lobe of papillary thyroid carcinoma (PTC) and to evaluate the diagnostic value of preoperative ultrasonography for multicentricity. METHODS: From January 1997 to December 2001, 93 patients with PTC underwent ultrasonography before total thyroidectomy. Ultrasonographic findings of multicentric foci in contralateral lobes were compared with histopathologic examination. RESULTS: Forty-four (47.3%) of the 93 patients were presumed bilateral PTC ultrasonographically, but 24 (25.8%) were confirmed histopathologically to have multicentricity in the contralateral lobes. Sensitivity and specificity of ultrasonography were 79.2% and 63.8%, respectively. False positive was 26.9%, consisting of 11 patients with benign diseases, 10 with normal glands, and 4 with intrathyroidal extension of PTC. False negative was 5.4%, which were all microcarcinoma with mean size of 0.3 cm. Ultrasonographic accuracy was 72.0%, but this was decreased to 35.3% in the cases of PTC combined with benign diseases. Clinical factors, except extrathyroidal invasion of PTC, were not related to multicentricity. CONCLUSION: Preoperative ultrasonography in PTC patients has a limited diagnostic value for multicentric foci within contralateral lobes, due to the technical variation of ultrasonography, combined benign diseases and diagnostic inaccuracy for micronodules.