Predictive Factors of Malignancy in Residual Thyroid Tissue after Partial Thyroidectomy in Patients with Differentiated Thyroid Cancer

Although partial thyroidectomy has lower operative risk, it potentially caries the risk of leaving residual malignancy. The aim of this study was to establish malignancy rate in residual thyroid tissue in patients with differentiated thyroid cancer (DTC) who underwent partial thyroid surgery and subsequently had completion thyroidectomy. We also investigated a number of clinical and biochemical factors that may anticipate the presence of malignancy in the thyroid remnant. Data of 58 patients with DTC who underwent completion thyroidectomy were retrospectively analyzed. Patients were divided into 2 groups based on the residual tissue pathology after completion thyroidectomy; the first group consisted of patients with malignant residual tissue, and the second group consisted of patients with benign residual tissue. Tumor histopathology type and serum thyroglobulin levels before completion thyroidectomy were compared between the two groups. Among 58 patients, 13 (22.4%) patients were found to have malignant residual tissue after completion thyroidectomy. No significant differences were found between the groups with respect to age, serum thyroglobulin level before completion thyroidectomy, primary tumor type, tumor size, bilateralism, multifocality, arterial invasion, thyroid capsular invasion, and extrathyroidal invasion. Residual thyroid volume was higher in patients with malignant residual tissue. In binary logistic regression analysis, residual thyroid volume was the only predictor factor for the presence of malignancy in the thyroid remnant. Malignancy in residual thyroid tissue is not uncommon. Thyroid remnant volume may be predictive of malignancy in residual thyroid tissue.