Score system for evaluation of morphological findings in cytological smear from thyroid nodules' fine needle aspiration in order to predict thyroid Carcinomas

Abstract

According to the last National Brazilian Cancer Institute (INCA) estimates, the incidence of thyroid cancer for each year of the 2020-2022 triennium, will be 13,780 new cases; 1,830 in men and 11,950 in women. Although most thyroid nodules are benign, it is a concerning finding. Among thyroid malignant neoplasms, there are different types of thyroid carcinomas showing distinctive morphological presentation and variable prognoses. It may influence the diagnostic tests and clinical outcomes. As the first evaluation of thyroid nodules, Fine Needle Aspiration Biopsy (FNAB) is a low-cost and non-invasive procedure. It is a screening test, which can identify nodules that need thyroidectomy, thereby minimizing the impact of surgical procedures on benign lesions. At the same time, it is a sensitive procedure, avoiding false-negative results. The high incidence of thyroid nodules, especially after the increasing popularity of imaging tests, justifies researches about those lesions, as well as the cytological criteria related to the diagnosis of malignancy, aiming to improve the FNAB accuracy. In the current literature, there are no papers that perform a comparative analysis of each cytological criteria (cellularity, amount of colloid, nuclei enlargement, nuclear grooves, nuclear pseudo inclusions, nuclear pallor, papillae, follicular arrangement, nuclear molding, etc) in order to identify their influence in the malignancy diagnosis. Objective: to create a scoring system and to develop a mobile application based on cytomorphological criteria for the evaluation of FNAB products of thyroid nodules in order to improve the accuracy and the reproducibility of Bethesda categories. Methods: This is an observational, analytical study based on retrospective analysis of the database and review of the slides from the archive of Instituto de Patologia de Araçatuba spending 6 years (January 1, 2016, to December 31, 2021), with an estimated 3,000 cases. Clinical information, such as gender, age, location (right lobe, left lobe, and isthmus) and ultrasound data (size, considering the measurement on the major axis,) will be collected from medical requisition forms. Cytological variables will be analyzed through microscopic analysis. The FNAB and the surgical specimen reports will be considered as outcome variables. The FNAB cytological results show the following categories, based on the Bethesda System for Reporting Thyroid Cytopathology: Category I (Non-Diagnostic), Category II (Benign), Category III (Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance), Category IV (Suspicious for Follicular Neoplasm or Follicular Neoplasm), Category V (Suspicious for Malignancy), Category VI (Malignant). The classification of the World Health Organization (presence x absence of carcinoma; classification regarding the histological variant, measurement, location, affected lymph nodes, perineural and angiolymphatic invasion) will support the surgical specimen analyzes as a categorical variable too. Aiming Results: we hope this project will help the final decision about the Bethesda category related to thyroid nodules, influencing the therapeutical decision and follow-up. The scoring system will be integrated into a mobile application to assist the diagnostic decision-making process through cytological examination, improving accuracy and reproducibility among different health services. (AU)