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NJBMS - Volume 4, Issue 1, July - September 2013

Pages: 55-61
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THYROID FNAC: EXPERIENCE WITH THYROID BETHESDA SYSTEM IN PRACTISE

Author: AMRIT KAUR KALER, RAJA PARTHIBAN, N. GANDHI, HTJ PRAKASH

Category: Pathology

Abstract:

The Bethesda system of classification of thyroid lesions as proposed by National Cancer Institute (NCI) [1] is excellent for reporting thyroid fine needle aspiration and demonstrates that the additional category follicular lesion of undetermined significance (FLUS) on the diagnosis of follicular lesions helps in better classification of thyroid fine needle aspiration cytology (FNAC). This prospective study was conducted on a series of 151 cases over a period of 2 years from 2007 to 2009 in the department of Pathology, Dr. B.R. Ambedkar Medical College, Bangalore to define the accuracy of FNAC based on Bethesda system. The distribution of the lesions was as follows: unsatisfactory 8.6%, benign 76.8%, FLUS 3.9%, follicular neoplasm 2.6%, suspicious for malignancy 0.6% and malignant 7.2%. There was an excellent association between the categories in predicting benign and malignant lesions. However, one case of follicular carcinoma and papillary carcinoma each was reported negative for malignancy on FNAC, hence two false negative cases were found. There were no false positive cases reported on cytology in our series. Given only 39% of patients underwent surgery, the sensitivity of thyroid FNAC for diagnosing the malignant thyroid nodule was 100%. But the sensitivity of thyroid FNAC as a screening test for all neoplasms was 91.0%. The specificity for diagnosing a malignant thyroid nodule and the specificity of thyroid FNAC as a screening test for all neoplasm is 100%. This positive predictive value and negative predictive value in a neoplastic process was 100% and 94.8% respectively, while in malignancy showed 100% each. The diagnostic accuracy of FNAC on Bethesda system was concluded as 96.6%.

Keywords: Bethesda System, Follicular lesion of undetermined significance (FLUS), Thyroid FNAC