FNAC accuracy in diagnosis of thyroid neoplasms considering all diagnostic categories of the Bethesda reporting system: A single-institute experience

Background: Thyroid fine-needle aspiration cytology (FNAC) is a valuable test used for diagnosing diseases of the thyroid gland. Aims: Using all satisfactory categories of the Bethesda system, this study aimed to determine the accuracy with which FNAC diagnoses thyroid neoplasms. We also discuss the factors that affect diagnosis accuracy. Settings and Design: A comparison was drawn between FNAC results and final histological diagnosis using samples collected over a period of 3 years. Materials and Methods: For all patients, age, sex, cytological features, and histological types were determined. All cases of false negative (FN) and false positive (FP) diagnosis were reanalyzed. Statistical Analysis Used: The chi-square test and univariate analysis were performed to examine the relationship between different variables. Results: About 52% of the cases were found malignant, and they were of six different histological types. Papillary carcinoma was the commonest type of malignancy at 76.9%. The rate of malignancy was 63% in males and 49.4% in females. In two of the FN cases, the tumor had a diameter of ≥35 mm. Of the 12 FP cases, nine were in the follicular neoplasm or suspicious for follicular neoplasm Bethesda category. FNAC diagnosis had 95.2% sensitivity, 68.4% specificity, 83.3% positive predictive value, 89.6% negative predictive value, and 85.14% accuracy. Conclusions: FNAC was found to have a high level of sensitivity and an acceptable degree of specificity in diagnosing different types of thyroid neoplasms. The presence of microfollicular structures or crowded cellular clusters is a challenge to diagnosis, particularly in low-quality specimens.