ABSTRACT
<p><b>OBJECTIVE</b>To study the diagnoses and treatments of small thyroid nodules (maximum diameter < 1 cm) with contralateral papillary thyroid microcarcinoma (PTMC).</p><p><b>METHODS</b>A total of 253 patients with unilateral PTMC and contralateral thyroid benign nodules identified by ultrasound before thyroidectomy was retrospectively analysed. All patients underwent near-total or total thyroidectomy. Chi-square test was used for univariate analysis and logistic regression test for multivariate analysis.</p><p><b>RESULTS</b>In 53 (20.9%) of 253 patients with unilateral PTMC, the contralateral thyroid benign nodules identified by ultrasound were confirmed pathologically as PTMC. Univariate analysis showed multifocality of the primary tumor and Hashimoto's thyroiditis were correlated with contralateral PTMC (χ(2) = 24.834, χ(2) = 5.182, P < 0.05). However, there were no significant differences for the existence of contralateral PTMC in age, sex, tumor size, capsule invasion, lymph node metastasis, the number of nodules and Tg-level. Multivariate analysis showed only multifocal PTMC was an independent predictive factor for contralateral PTMC (OR = 5.352, P < 0.05).</p><p><b>CONCLUSIONS</b>The patients with unilateral multifocal PTMC have a high rate of PTMC in contralateral small thyroid nodules. However, it is very difficulty to define by ultrasonography preoperatively. The total thyroidectomy maybe serve as a useful treatment.</p>