A Comparative Analysis of Liquid-Based Cytology and Conventional Smears in Fine-Needle Aspirates of Thyroid Lesions

Abstract

Background Palpable nodules in the thyroid are present in 4-7% of the general population. Fine-needle aspiration cytology is a safe and cost-effective method of choice for evaluating thyroid nodules. Aspirated samples can be manually spread directly onto the slide and stained in the conventional smear method. The liquid-cased cytology method has been recently introduced, which is an automated machine-based method, yielding a single slide with a clean background and greater preservation of cells and consuming less time for screening. This study aimed to compare the cytomorphological features and diagnostic accuracy of conventional smears and liquid-based cytology smears. Methodology This prospective study comprised 250 cases of thyroid lesions. Fine-needle aspiration cytology using conventional smears and liquid-based cytology smears was reported per the Bethesda system of reporting thyroid cytopathology. Detailed cytomorphological features were evaluated and compared in both techniques. Results The cellularity of conventional smears was significantly higher for scores 2+ and 3+ than paired liquid-based cytology smears (paired t-test, p < 0.001). The overall diagnostic efficacy of conventional smears and liquid-based cytology smears was equivalent in the majority of cases (n = 171, 68.4%). Conventional smears were better than liquid-cased cytology smears in 34 (13.6%) cases, and liquid-based cytology smears were better than conventional smears in eight (3.2%) cases. Liquid-based cytology smears showed a higher unsatisfactory rate compared to conventional Smears (15.6% vs. 5.2%). The sensitivity and specificity of conventional smears were 84.6% and 94.4%, respectively, compared to 68.7% and 92.4%, respectively, of liquid-based cytology smears. Conclusions Conventional smears are a cost-effective and easy method for diagnosing thyroid nodules. Liquid-based cytology smears can be used in association with conventional smears to enhance the accuracy of the evaluation of malignant thyroid nodules.

Diagnostic Accuracy of Fine-Needle Aspiration Cytology (FNAC) in Thyroid Nodule Excision Cases

“…It gives an advantage to a clean background for the monolayered cells with well-preserved morphology and consumes less screening time. Liquid-based cytology is widely used in gynecological smears nowadays; however, a few studies have been reported in the literature for the interpretation of thyroid nodules [28].…”

“…Some previous studies concluded that liquid-based cytology serves as a useful adjunct diagnostic method, and its combination with conventional smears has been shown to reduce unnecessary thyroidectomies due to the good identification of malignant and suspicious thyroid lesions [28,29]. However, a recently published meta-analysis study by Kang et al in 2024 [30] concluded that the diagnostic accuracy of FNAC in thyroid nodules did not significantly differ among conventional and/or liquid-based cytology, but comparing two kits (ThinPrep and SurePath) revealed a significant difference, suggesting that SurePath kits might be more accurate.…”

Comparison of Liquid-Based Preparations with Conventional Smears in Thyroid Fine-Needle Aspirates: A Systematic Review and Meta-Analysis

“…It is recognized for its simplicity and convenience [8]. Furthermore, it is relatively safe, repeatable, and low risk [6,7,9,10]. However, CS can report variable results, depending on the uneven thyroid tissue samples or cytopathologist's experience [8,10,11].…”

“…However, CS can report variable results, depending on the uneven thyroid tissue samples or cytopathologist's experience [8,10,11]. Artifacts may also arise during the drying of specimens, and results can vary by technician [9]. In addition, the presence of fibrosis and cystic lesions can result in poor cellularity [8].…”

“…Two commonly used kits are ThinPrep (Hologic, Marlborough, MA, USA) and SurePath (BD Diagnostics-TriPath Imaging, Burlington, NC, USA). LBP involves collecting aspirates in a special fixative and employing an automated machine to reduce cell debris, inflammatory cells, red blood cells, and artifacts, thus producing a uniformly distributed Papanicolaou smear slide [8,9]. Through processes such as homogenization, vacuum application, and sedimentation, it provides well-preserved sample cells against a clean background [8,10].…”