Accuracy of Fine Needle Aspiration Cytology in Solitary or Dominant Nodular Goitre: A Single Centre Study

Background: Thyroid swelling or goitre is a common condition, either asymptomatic or symptomatic. The diagnosis is usually established by ultrasound or fine needle aspiration cytology (FNAC) as a gold standard. The sensitivity of the test is inversely related to increasing size of the nodule. The objective of this study is to evaluate the accuracy of FNAC especially in cases of large goitre. Material and methods: This is a retrospective study on patients who underwent thyroidectomy between January 2000 to December 2007 for solitary or dominant nodular goitre. The analysis was made only on those patients with complete data on FNAC and histology. Result: There were 235 patients, but only 161 patients were analysed after excluding the suspicious and inadequate sample. The patients’ mean age was 42.1 year old (21 to 60). The size of the thyroid nodule ranged from 2.1 to 5.0 cm (mean = 3.9 cm). The overall sensitivity was 67.4% and the overall accuracy was 86.3%. The accuracy of FNAC according to the sizes above and below the value were as follows; 2 cm (72.2% vs. 88.1%); 3 cm (88.0% vs. 87.4%) ; 4 cm (86.6% vs. 84.4%) ; 5 cm (87.3% vs. 78.8%). This was most obvious in the sensitivity of the FNA which also showed reducing trend as the nodules increased in size. Conclusion: FNAC is an essential diagnostic tool in the management of nodular goitre. Our study showed that the accuracy of FNAC decreased as the size of the nodule getting bigger. Cautious approach should be taken in the management of large goitre and decision should not be based only on the result of FNAC.