Papillary thyroid microcarcinoma: retrospective analysis of 160 cases

Aims: This study aims to retrospectively evaluate the clinical and histopathological features of 160 cases diagnosed with papillary thyroid microcarcinoma (PTMC) and to determine the factors affecting the behavior of the tumor. Although PTMC generally has a benign course, it is aimed to contribute to clinical management strategies by defining the aggressive features it exhibits in some cases. Methods: 160 cases diagnosed with PTMC at the Department of Pathology of Tokat Gaziosmanpaşa University Faculty of Medicine between January 2010 and December 2023 were included in the study. Pathology reports of the cases were retrospectively examined; age, gender, number of tumor foci, location, tumor diameter, histological type, capsule invasion, lymphovascular invasion, extrathyroidal spread, presence of lymph node and distant metastasis, and accompanying thyroid diseases were recorded. In addition, preoperative thyroid fine needle aspiration biopsy results and surgical methods were analyzed. Statistical analyses were performed using SPSS 22.0 program. Results: The mean age of the 160 cases was 48.4 years, and 78.1% were female. 65.6% of the tumors were unifocal, 34.4% were multifocal, and 20% were bilateral. The mean tumor diameter was 5.2 mm, and 59.4% of the cases had a diameter of 5 mm or smaller. Among the histological types, 51.3% were follicular, 43.7% were classical variants. Extrathyroidal spread was observed in 5.6% of the cases, lymphovascular invasion in 3.75%, and lymph node metastasis in 2.5%. The most common diagnosis in 28.4% of the cases in which thyroid FNAB was performed was “atypia of undetermined significance”. The most common accompanying thyroid diseases were multinodular goiter in 46.3% and Hashimoto thyroiditis in 33.8%. Conclusion: Although PTMC generally has a benign course, it can exhibit aggressive behavior such as multifocality, extrathyroidal spread, and lymph node metastasis in some cases. Therefore, an individualized treatment approach should be adopted by considering not only the tumor diameter but also all histopathological features. Due to the heterogeneous nature of PTMC, it reveals the need for prospective and multicenter advanced studies.