Retrospective evaluation of the incidental finding of 403 papillary thyroid microcarcinomas in 2466 patients undergoing thyroid surgery for presumed benign thyroid disease

Nikola Slijepcevic, Vladan Zivaljevic, Jelena Marinkovic, Sandra Sipetic, Aleksandar Diklic, Ivan Paunovic

The aim of our study was to investigate the incidence of papillary thyroid microcarcinoma (PTMC) in patients operated for benign thyroid diseases (BTD) and its relation to age, sex, extent of surgery and type of BTD. Retrospective study of 2466 patients who underwent thyroid surgery for BTD from 2008 to 2013. To determine independent predictors for PTMC we used three separate multivariate logistic regression models (MLR). There were 2128 (86.3%) females and 338 (13.7%) males. PTMC was diagnosed in 345 (16.2%) females and 58 (17.2%) males. Age ranged from 14 to 85 years (mean 54 years). Sex and age were not related to the incidence of PTMC. The overall incidence of PTMC was 16.3%. The highest incidence was in Hashimoto thyroiditis (22.7%, χ(2) = 10.80, p < 0.001); and in patients with total/near-total thyroidectomy (17.7 %, χ(2) = 7.05, p < 0.008). The lowest incidence (6.6%, χ(2) = 9.96, p < 0.001) was in a solitary hyperfunctional thyroid nodule (SHTN). According to MLR, Hashimoto thyroiditis (OR 1.54, 95% CI 1.15-2.05, p < 0.003) and SHTN (OR 0.43, 95% CI 0.21-0.87, p < 0.019) are independent predictors. Since the extent of surgery was an independent predictor (OR 1.45, 95% CI 1.10-1.92, p = 0.009) for all BTD, and sex and age were not; when the MLR model was adjusted for them, Graves disease (OR 0.72, 95% CI 0.53-0.99, p < 0.041) also proved to be an independent predictor. Sex and age are not statistically related to the incidence of PTMC in BTD. The incidence of PTMC is higher in Hashimoto thyroiditis and patients with total/near-total thyroidectomy; and lower in patients with a SHTN and Graves disease.