RESUMEN
BACKGROUND AND OBJECTIVES: Papillary thyroid carcinoma (PTC) frequently occurs as multifocal and bilateral tumors. However, multifocality and bilaterality are not easy to detect preoperatively and contralateral remnant tumor might lead to reoperation after hemithyroidectomy. We aimed to demonstrate the frequency of bilaterality and predictive factors for occult contralateral PTC when a frozen biopsy of hemithyroidectomy shows multifocal PTCs in one of the lobes. SUBJECTS AND METHOD: One hundred and thirty patients with PTC were enrolled in this study. All patients underwent hemithyroidectomy and frozen biopsy, followed by total thyroidectomy because of ipsilateral multifocality. Medical records, pathologic results, and preoperative ultrasound results were reviewed retrospectively. Patients were divided into two groups depending on bilaterality (unilateral or bilateral). RESULTS: Bilaterality was detected in 74 of 130 patients (56.9%). Bilateral group showed more number of carcinomas (3.9±1.4 vs. 2.3±0.9) and more tendency of existence of contralateral nodule (87.8% vs. 55.3%). Tumor size of 1 cm or more and contralateral nodules were significant predictive factors for the existence of occult contralateral PTC. The suspicious sonographic feature of contralateral nodule had 75.7% sensitivity and 75% specificity for detecting bilaterality. CONCLUSION: The incidence of bilateral PTC is high in patients with ipsilateral multiple tumors. When the frozen biopsy result shows multifocality in one of the lobes, the remnant tumor may lead to reoperation under recent guidelines on thyroid surgical extent. Characteristics of contralateral nodule can help physicians and patients to make the decision regarding surgical extent.