Thyroid nodules are common. Fine-needle aspiration cytology (FNAC) is a diagnostic tool used to enhance or reduce the pre-test probability of thyroid neoplasm. As a clinician, we need to understand what a specific FNAC result means to an individual patient's management.

To determine the value of FNAC in the diagnosis of thyroid nodules, thyroid cytology of 57 patients with definitive histology after surgery was analyzed. FNAC was correlated with histology and the sensitivity and the specificity were calculated.

Our study included 55 women and 3 men. The mean age of the patients was 40 years old. Cytological findings of the lesion were reported as benign in 43 cases, as malignant in 6 cases, suspicious for malignancy in 7 cases and inconclusive in 2 cases. Histopathologic findings were compatible with benign thyroid lesions in 48 cases and malignant lesions in 10 cases. The study of the correlations between the cytological data and histological findings showed a kappa's coefficient of 0,67. In fact, in 45 cases the histological and cytological findings were concordant. There were 6 cases of true positive FNAC and 4 false negative malignant FNAC. The overall sensitivity of FNAC detecting thyroid neoplasia was 60% and specificity 100%.

FNAC was essential to management in this series of patients. “Malignant” or “suspicious for malignancy” cytology are absolute indicators for thyroidectomy. FNAC should be undertaken with ultrasound guidance and if possible, with a pathologist in attendance to assess sample adequacy.