Role of fine-needle aspiration cytology in the diagnosis of thyroid diseases

Background Fine-needle aspiration cytology (FNAC) is a gold standard investigation in the diagnosis of thyroid diseases. It is a simple, safe, cost-effective, and quick-to-perform procedure, with excellent patient compliance. It has high sensitivity, specificity, and accuracy as a preoperative investigation of thyroid gland diseases. Aim To determine the accuracy of FNAC in the diagnosis of thyroid diseases and to correlate the relationship between FNAC findings and histopathology of excised specimen. Patients and methods This was a prospective study conducted on 80 patients between September 2015 and September 2017. All patients with thyroid lesions were subjected to FNAC at Al Zahraa University Hospital. All patients with a clinically diagnosed solitary thyroid nodule, euthyroid multinodular goiter, and hypothyroid or hyperthyroid were excluded from this study. Results The study population was female predominant, represented by 73 (91.25%) patients, with age ranging from 18 to 65 years. Most cases were non-neoplastic, representing 42 (52.5%) cases, whereas 12 (15%) cases were neoplastic. The commonest lesion in thyroid gland was colloid goiter, and papillary carcinoma was the commonest among malignant lesion. On statistical analysis of our study, data showed the diagnostic accuracy of FNAC to be 80%, sensitivity to be 80%, and specificity to be 87.5% in neoplastic lesions, but results in carcinomatous lesions had accuracy of 92.5%, sensitivity of 80%, and specificity of 95.38%. Conclusion FNAC is an excellent first-line method as a preoperative investigation of thyroid swelling showing the nature of the lesion. It is a safe, minimally invasive, cost-effective diagnostic tool and correlates with the findings of tissue biopsy.