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Clinical and molecular analyses of thyroid cancer in patients treated for benign diseases.

Incidental thyroid carcinoma (ITC) is defined as a tumor diagnosed at histology after surgical intervention for a benign thyroid disease and, therefore, without a preoperative diagnosis of malignancy. The prevalence of ITCs reported in the 20 papers of the literature is extremely variable (3.3–21.6%), mostly due to the relatively low number of cases included (Ugolini et al. 2007, Bradly et al. 2009, Barczyński et al. 2011, Minuto et al. 2013, Negro et al. 2013), and scanty molecular data are available (Ugolini et al. 2007). A more accurate estimation of the actual prevalence of ITCs is of particular importance for the preoperative counseling of patients undergoing thyroidectomy for a supposed benign disease. Moreover, the definition of the clinical behavior of this category of tumors is crucial for the choice of the best postsurgical treatments and follow-up. The aim of this study was to investigate the prevalence, clinical features, and BRAF mutational status of ITCs of any dimension in a large consecutive cohort of patients referred to our Endocrine Surgery Center for benign thyroid disease. The approval of the Ethical Committee was obtained for this retrospective observational study (#139/2013). Between February 1997 and March 2011, 2045 patients were subjected to thyroidectomy at the Endocrine Surgery Unit for benign disease. The preoperative diagnosis was uninodular or multinodular goiters (MNGs) in 1405 cases, toxic uninodular goiter or toxic MNGs (TMNGs) in 332 cases, Graves’ disease (GD) in 300 cases, Hashimoto’s thyroiditis in six cases, and iatrogenic thyrotoxicosis in two cases. The preoperative diagnosis was based on a benign cytology observed during ultrasound-guided fineneedle aspiration biopsy (FNAB) performed on either thyroid nodules with suspicious ultrasound features or the largest thyroid nodule if no suspicious features were detected. In TMNGs, only nodules with a normal or reduced uptake were subjected to FNAB. All cases with an indeterminate cytology were excluded. The surgical