Papillary Thyroid Microcarcinomas: a 25 Years Retrospective, Institutional Study of 255 Cases

Abstract

Background: Papillary thyroid microcarcinoma (PTMC) defines a group of papillary thyroid carcinomas, incidentally discovered, measuring 1 cm or less. The aim of our study was to evaluate the incidence and the pathological characteristics of PTMCs in our institution in the last 25 years, with special emphasis on the prognostic factors related to PTMCs. Material and methods: We performed a retrospective, cohort study on 255 PTMCs, registered in the Department of Pathology, Tîrgu-Mureş Emergency County Hospital between 1990 and 2014. Results: A significant increase in the incidence of PTMCs was observed in the 2004-2014 period, compared to 1990-2003 (7.6%, 229 PTMCs/3005 thyroid specimens vs. 1.2%, 23 PTMCs/1885 thyroid specimens). Conventional PTMCs accounted for most of PTMC cases (n=123 cases, 48.2%), followed by the follicular variant of PTC (n=117 cases, 45.9%). The increasing incidence of PTMCs was associated with a significant increase in the routine number of blocks sampled per case over the study period (R2 =0.72, p < 0.001). By means of the univariate and multivariate analysis, three risk factors were predictive for extrathyroidal extension in PTMCs: multifocality (Odds ratio [OR] 4.97, p-0.002), tumor size ≥ 5mm (OR 8.97, p-0.008) and lymph node involvement (OR 17.66 p<0.005). Conclusion: The incidence of PTMCs has revealed a significant increasing trend in our institution over the last 25 years. Multifocality, lymph node involvement and tumor size ≥ 5mm were found to be risk factors for extrathyroidal extension. These prognostic factors must be evaluated and clearly mentioned in the pathological report, to help a correct estimation of biological potential of the lesion and an appropriate postoperative management.

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

“…Among them, increased surveillance of the general population, with the widespread use of neck ultrasound (US) examination and fine-needle aspiration (FNA) biopsy of the thyroid nodules, has played an important role [ 1 , 8 , 9 ]. Moreover, recent advances in sampling techniques and more careful examination of thyroid specimens resected for benign diseases have resulted in the detection of many PTMCs [ 10 ]. For all these reasons, PTMCs are responsible for a phenomenon referred to as thyroid cancer “overdiagnosis” [ 11 , 12 , 13 , 14 ] or as an “epidemic of diagnosis” [ 12 ].…”

High-risk morphological features are less prevalent among small (<5mm) papillary thyroid microcarcinomas compared to larger (≥5mm) tumors: a study of 206 cases

“…This increase might be explained by the widespread use of imaging techniques and fine needle aspiration (FNA) biopsy of small thyroid nodules, allowing the identification of a large number of clinically silent PTMCs [5]. Moreover, many PTMCs have lately been detected following advances in the sampling technique and a more watchful and careful examination of the thyroid specimens resected for benign diseases [6]. All this together, resulted in an increased detection of PTMCs, considered as a global phenomenon called epidemic of overdiagnosis [1,7,8].…”