Introduction: Thyroid nodules are a common clinical entity found among the adult general population. With increasing use of imaging investigations like ultrasonography, there has been a significant rise in the detection of non-palpable thyroid nodules that require further evaluation and management. The routine use of FNAC has reduced the number of unnecessary surgical procedures for thyroid nodules. Taking a decision as to whether to operate on a thyroid nodule is dependent on accurate FNAC testing. This study describes the experience with FNAC in a consecutive series of patients with thyroid nodules who underwent thyroidectomy at a tertiary care hospital in the department of endocrine surgery.
Patients and methods: Clinical and pathologic data of patients with thyroid nodules or diffuse goitre who were operated in a single endocrine surgical unit between January 2008 and December 2010 were prospectively collected and retrospectively reviewed. The anatomical lesion of the thyroid (solitary nodule, STN, multinodular goitre, MNG or diffuse goitre, DG) was recorded. The functional status of the thyroid was assessed for each patient at presentation. All patients included in the study underwent fine needle aspiration cytology (FNAC) followed by surgery. Patients with solitary toxic nodules underwent hemithyroidectomy, while others underwent total thyroidectomy. Final histopathology (HPE) was then compared with initial FNAC results.
Results: Out of the total number of 702 patients, 119 (17%) were men and the remaining 583 (83%) were women. With regards to solitary thyroid nodules, FNAC had a sensitivity of 86.9%, specificity of 99.1%, false negative rate of 13.1%, false-positive rate of 0.9%, positive predictive value of 97,6% and negative predictive value of 94.9% for diagnosis of malignancy. FNAC had a sensitivity of 76.9%, specificity of 98.8%, false negative rate of 23.1%, false-positive rate of 1.2%, positive predictive value of 94.6% and negative predictive value of 93.8% for diagnosis of malignancy with respect to diffuse and multinodular goitre. Overall, FNAC had a sensitivity of 80.2%, specificity of 98.9%, false negative rate of 19.8%, false-positive rate of 1.1%, positive predictive value of 96.6% and negative predictive value of 94.1% for diagnosis of malignancy.
Conclusion: FNAC was more accurate in patients with solitary thyroid nodules than in those with multinodular or diffuse goitre. While false negativity could be due to misrepresentative sample or misinterpretation of the sample, false positivity could be ascribed to hyperplasia of thyrocytes in the functioning thyroid as a result of TSH stimulation.
Thyroid nodules are a common clinical entity found among the adult general population. The frequency of non-palpable thyroid nodules may be as high as 50% or more by the age of 50 years.1,2 With time, ultrasonography has come to be used with increasing regularity in clinica
FNAC of Thyroid, Solitary Thyroid Nodule, Nodular Goitre, HPE, sensitivity, specificity