association between tumor size and bilateral involvement in papillary thyroid carcinoma

Background. Tumor multifocality and bilaterality of papillary thyroid carcinoma (PTC) are important factors when selecting the most appropriate surgical procedure. The aim of this study was to assess the bilaterality rate in PTC and the relationship between the tumor size and bilaterality. Materials and Methods. Thyroidectomy specimens with a diagnosis of PTC were retrospectively reviewed in the Pathology Department of a tertiary care medical center. Specimens were divided into three groups according to the size of the primary and contralateral tumor foci. Tumors less than or equal to 1 cm in each lobe were included in group 1. Group 2 consisted of tumors greater than 1 cm in one lobe and less than 1 cm in the other lobe. Tumors greater than 1 cm in each lobe were included in group 3. Results. We identified 868 total thyroidectomy specimens with a diagnosis of PTC between 2001 and 2011. Of these cases, both thyroid lobes were involved in 262 cases (32%). There were 109 (42%), 121 (46%), and 32 cases (12%) in group 1, group 2, and group 3, respectively. Conclusion. Bilaterality is frequent in PTC and is not related to tumor size. Accordingly, the high frequency of bilateral disease in PTC should be kept in mind when determining the extent of the surgical procedure.