Risk stratification of papillary thyroid microcarcinomas via an easy-to-use system based on tumor size and location: clinical and pathological correlations

Introduction: We aimed to determine whether two clinically accessible parameters, tumor size and location within the thyroid, correlate with clinicopathological features that are predictors of high risk in papillary thyroid microcarcinomas (PTMCs). Materials and Methods: PTMC cases were obtained from the database of the Department of Pathology, Emergency County Hospital, Târgu Mureş, Romania. Four tumor groups were created based on tumor size and location: Group I (≥5 mm, subcapsular), Group II (≥5 mm, nonsubcapsular), Group III (<5 mm, subcapsular), and Group IV (<5 mm, nonsubcapsular) PTMCs. Clinicopathological features and follow-up data were compared by univariate and multivariate analysis. Results: Our study included 164 PTMCs (n=70/20/19/55 in Groups I/II/III/IV, respectively). High-grade morphological features, such as plump pink cells (p=0.010), tumor desmoplasia (p=0.022) and sclerosis (p=0.001), infiltrative tumor borders (p=0.005), positive resection margins (p=0.005), invasion into the perithyroid adipose tissue (p=0.001), irregular nuclear membranes (p=0.004), and pseudoinclusions (p=0.001) were significantly more prevalent among Group I PTMCs. Group IV PTMCs were characterized by a paucity of the above-mentioned morphological features, while Group II and III PTMCs displayed intermediate morphological profiles. Conclusions: Group I PTMCs proved to be associated with more aggressive morphological features and might need a more careful clinical approach.