Reliability of FNAC in diagnosing thyroid malignancy

Introduction

Thyroid diseases are common disorders with a great geographical variation worldwide. Underlying pathology of a thyroid swelling can be variable, with thyroid cancer being the most sinister pathology of all. Fine Needle Aspiration Cytology (FNAC) is a widely accepted, simple and minimally invasive investigation in the assessment of nodular thyroid disease.

Objectives

This study was conducted to evaluate the reliability of FNAC in diagnosing malignant thyroid conditions.

Material and methods

Retrospective analysis of patients who underwent thyroidectomies in a teaching hospital during a ten month period was considered in the study. Their preoperative FNAC diagnosis was compared with the post operative histopathological diagnosis.

Results and conclusion

Data from 94 patients who underwent FNAC and subsequent histological examination were collected. Eight patients were excluded due to inadequate information given for a conclusive diagnosis. Out of the remaining 86 patients 44 had colloid nodules 16 had thyroiditis 24 had papillary carcinomas and 2 had follicular neoplasms. The FNAC reliability in diagnosing thyroid malignancy was concluded as sensitivity 73%, specificity 85%, positive predictive value 67.8% and negative predictive value of 87.9%. This is consistent with the recent reports in the literature that suggest sensitivity, specificity, positive and negative predictive values of FNAC in detecting thyroid diseases ranging from 84-98%, 67-100%, 34-92%, and 65-94% respectively.

The Sri Lanka Journal of Surgery 2015; 33(2): 29-31