Correlation of fine needle aspiration cytology with histopathology for thyroid swellings in a tertiary care hospital in South India

Carlos Eduardo Pereira ,D Rohan ,L Tauro

doi:10.15372/ssmj20200509

Abstract

Fine needle aspiration cytology (FNAC) is documented to be a good tool in the diagnosis of thyroid lesions. It has good diagnostic accuracy and is an inexpensive investigation. Although a good instrument it does have its own limitations especially when it comes to distinguishing a follicular adenoma from follicular carcinoma thyroid. Objectives of the study was the evaluation of FNAC in the diagnosis of thyroid lesions by determining its sensitivity, specificity, diagnostic accuracy, positive predictive value and negative predictive value. Material and methods. This is a retrospective study of 580 cases of thyroid swelling admitted to our hospital and undergone thyroidectomy over a period of 5 years from 2015 to 2020. After thyroidectomy, FNAC reports (Bethesda system for reporting) of those patients were collected and were compared and analyzed with the histopathology reports. Category 1 and category 3 cases were excluded from calculation due to uncertainty in reporting. Data were analyzed to calculate the sensitivity, specificity, diagnostic accuracy, positive predictive value and negative predictive value of FNAC. Results. Our study included a total of 580 cases of thyroid swellings. The male to female ratio was 1:18.2 and the median age was 43 years. On FNAC, 428 cases (73.7 %) were benign, 35 cases (6 %) were indeterminate, 39 cases (6.7 %) were follicular neoplasm, 30 cases (5.1 %) were suspicious for malignancy and 34 (5.8 %) were malignant. 14 (2.4 %) cases were unsatisfactory. Cytology report was then compared with histopathological reports. FNAC had a sensitivity of 84.2 %, specificity of 97.2 % and a diagnostic accuracy of 94.5 %. The positive predictive value and negative predictive value were 88.3 and 96 % respectively. Conclusions. FNAC is a more specific than sensitive when distinguishing between benign and malignant lesions of thyroid. It has good diagnostic accuracy and hence should be used in all tertiary care hospitals prior to surgery in diagnosing thyroid lesions.

Highlights

Thyroid swellings are quite common in the ge neral population and predominantly affect women as compared to men
This is a retrospective study of 580 diagnosed cases of thyroid swelling that presented to the general surgery, surgical oncology and Ear, Nose and Throat Out-Patient Departments of Father Muller hospital in the period between January 2015 and December 2019
Fine needle aspiration cytology (FNAC) results were compared with histopathology reports to calculate the sensitivity, specifici ty, positive and negative predictive value of FNAC in diagnosing thyroid lesions

Summary

Introduction

Thyroid swellings are quite common in the ge neral population and predominantly affect women as compared to men. Based on a study conducted in south India, thyroid swellings can be clinically detected in about 12 percent of adult population [1]. There are numerous etiologies for thyroid swellings and this is commonly classified as either benign or malignant. It is important to distinguish between the two since the modality of treatment varies conside rably. The aim of investigations is to determine the cause of thyroid swelling and to rule out malignancy [2]. 5 % of individuals with thyroid swellings are found to have malignant nodules [3]. In India, 5–6 % of thyroid cancers occur in women and 2 % are seen in men [4]

Objectives

Methods

Results

Conclusion