The diagnostic value of fine needle aspiration cytology in thyroid swellings in a University Hospital, Yemen

OBJECTIVE: To evaluate the correlation between the fine needle aspiration (FNA) cytology and the histopathological findings in cases of the thyroid swellings and to assess the accuracy of cytological examination of thyroid nodules.

METHODS: This study was carried out at Kuwait University Hospital, Sana'a, Yemen. There were 243 thyroid FNAs of which 199 had subsequent excisional histopathological examination in the period 1997 to 2001. All the records of cytology and histology were reviewed. Cases were classified into 6 subsets: benign follicular lesion, thyroiditis, follicular neoplasm, suspicious for papillary carcinoma, malignant, and non-diagnostic aspirate. For statistical analysis, we excluded cases, which had not had subsequent histopathological examination (n=44), and cases with non-diagnostic aspirate (n=3), so only the histology and medical records of 196 cases were reviewed and correlated with the cytology results.

RESULTS: There were 156 (78.4%) cases of benign aspirate, 31 (15.6%) cases of follicular neoplasm, 4 (2%) cases that were suspicious for papillary carcinoma, 4 (2%) cases of papillary carcinoma, and 3 (1.5%) cases of non-diagnostic aspirates. The 196 cases, which underwent cytological and histopathological examinations, were classified as non-neoplastic and neoplastic (including follicular neoplasm and malignancy) according to postoperative histopathology and correlation which, was carried out with preoperative cytology. There were 115 true negatives, 26 true positives, 42 false negatives, and 13 false positives. This gives a sensitivity of 38%, specificity of 89.9%, positive predictive value of 66.7%, negative predictive value of 73.2%, and accuracy of 72%.

CONCLUSION: The sensitivity of FNA cytology in this study is very low compared to published studies, which had adversely affected the surgical decision making as well as the outcome. We should realise that negative FNA cytology does not exclude malignancy and we have to seriously evaluate the situation and to rethink on how to raise the scale of sensitivity in FNA cytology in the diagnosis of thyroid nodules, and to improve the level of expertise in cytology.