Introduction: Thyroid nodules are a common disorder of the thyroid. Most of these are benign and only 5%-30% are malignant. Fine-needle aspiration cytology (FNAC) plays a vital role in differentiating benign from malignant and hence directing toward timely intervention. Liquid-based cytology (LBC) has been recently started in sampling thyroid lesions and has shown good results. The aim of our study was to compare the cytomorphology of thyroid lesions by conventional smear (CS) and LBC method and categorize the lesions according to TBSRTC (The Bethesda System for Reporting Thyroid Cytopathology).
Materials and methods: A prospective study was conducted from January 2018 to June 2019 on 131 patients. Thyroid FNAC samples were taken to prepare 2-5 slides for conventional reporting and one sample for LBC preparation by SurePath method. Staining with hematoxylin and eosin, May-Grünwald-Giemsa, and Papanicolaou stain was done. Cases were reported by TBSRTC and compared.
Results: The nonneoplastic lesions constituted the major proportion on both CS (83.2%) and LBC (73.2%). The neoplastic lesions constituted only 9.9% of all the diagnosis both on CS and LBC smear. The kappa agreement between CS and LBC cytology as per The Bethesda System for Reporting Thyroid Cytopathology came out to be 0.715, which was statistically significant.
Discussion: Colloid appearance was statistically significant on comparison by both methods. The comparison of ill formed epithelioid granulomas was statistically significant in autoimmune thyroiditis cases. In malignancy cases, nuclear and cytoplasmic details were crisper on CS. Cytoplasm appeared fragile and fragmented on LBC smears.
Keywords: Fine-needle aspiration cytology; TBSRTC; liquid-based cytology; malignant; thyroid.