Incidentally Discovered Papillary Thyroid Microcarcinoma in Patients Undergoing Thyroid Surgery for Benign Disease

IntroductionIncidence of thyroid carcinoma (TC) has grown significantly over the last few decades worldwide, partly due to the increase detection of small thyroid microcarcinoma (TMc). TMc are tumors with a maximal diameter ≤ 1 cm, identified during histopathology examination following a thyroidectomy performed for reasons not pertaining to malignancy. The aim of this study is to investigate the prevalence of papillary thyroid microcarcinoma (PTMc) according to the nature of benign pathology that submit patients to thyroid surgery and its trend evolution.MethodsRetrospective cohort analysis of 1815 patients who underwent total thyroidectomy for non-malignant disease from 2005 to 2020. ResultsThe mean age of subjects was 53.5 years, with a higher proportion of women (1481, 82.1%). A total of 167 PTMc (9.3%) were incidentally discovered. Multivariate logistic regression analysis shows no differences in prevalence according to sex or age in patients with PTMc compared to those with final benign histology. Multinodular goiter increases the risk of PTMc with an odds ratio of 2.2 (p=0.001) compared to Hashimoto's thyroiditis and Graves´ disease (GD). There is a statistically significant increase in the incidence of PTMc in the group operated between 2017-2020 vs. 2005-2008 (p=0.005)ConclusionOverall prevalence of PTMc in patients who underwent thyroid surgery for benign disease was 9.3%. Thyroid nodular hyperplasia was the most frequent benign pathology associated to this occult cancer as compared to Hashimoto or GD. Gender and age were not correlated with prevalence of TMc. Over the years, surgical findings of PTMc have grown, particularly in the 2017-2020 period.