Highlights in the Diagnostic Dilemma of Solitary Thyroid Nodule; Fine Needle Aspiration Cytology in Comparison of Isotope Thyroid Scan

Thyroid nodules are common, with up to 8 % of the adult population having palpable nodules. With the use of ultrasound, up to 10 times more nodules are likely to be detected. The majority of thyroid nodules are benign and asymptomatic. The primary aim in investigating a thyroid nodule is to exclude the possibility of malignancy, which occurs in about 5 % of nodules. Objective. This was a comparative study between fine needle aspiration cytology and thyroid scan used to diagnose the solitary thyroid nodule and histopathology was used as gold standard to compare the results of both modalities. Materials and Methods. This study comprised of 40 patients with solitary thyroid nodules presented to endocrinology clinic in outpatient department. After clinical examination and ultrasound documentation, these patients were referred to nuclear medicine unit, for isotope thyroid scan. These patients underwent fine needle aspiration cytology in the department of Pathology. The cases were operated and evaluated for histopathological changes. Results. On thyroid scan, 30 patients (75 %) having cold nodule were labeled as suspicious 10 patients (25 %) had hot nodule. On FNAC 23 patients (57.5 %) had benign lesion, 13 patients (32.5 %) had indeterminate lesion and 4 patients (10 %) had malignant lesions. On histopathology, 36 patients (90 %) were confirmed to have benign lesions and 4 patients (10 %), malignant lesions. After comparison of results of thyroid scan and fine needle aspiration cytology with histopathology, the sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of thyroid scan were 75 %, 25 %, 10 %, 90 % and 30 %, respectively whereas those of fine needle aspiration cytology were 75 %, 97.2 %, 75 %, 97.2 % and 95 %, respectively. Conclusion. Fine needle aspiration was a significantly better predictor of malignancy than thyroid scan and resulted in a smaller proportion of excisions for benign nodules.