Diagnostic Accuracy of Fine Needle Aspiration Cytology for Thyroid Tumours at a Tertiary Hospital in Northern Tanzania

Abstract

Background: Thyroid diseases are common and serious diseases in the world and because of this fact, early diagnosis is necessary. Clinicians in our settings rely on clinical presentation, physical examination and biochemical findings in diagnosing patients with thyroid mass and sometimes this leads to misdiagnosis or late diagnosis of cancerous lesions. Abnormal lymph node sometimes can be mistaken for a thyroid nodule. Clinical examination or biochemical findings become difficult differentiatingdifficult differentiating the two conditions. The global consensus is to employ FNAC as standard baseline test to pick out thyroid lesions with malignancy potential. The inherent pitfalls and unique presentation in developing countries have proven a challenge in using FNAC as a stand-alone tool for preoperative assessment
Objective: To determine the diagnostic accuracy of fine needle aspiration cytology for thyroid tumours at a tertiary hospital in Northern Tanzania from January 2019 to June 2023.
Methodology: A retrospective cross sectionalcross-sectional hospital-based study that was conducted from January 2019 to June 2023 in patients who had thyroidectomy done during the study period at KCMC. Structured Questionnaires were used to collect key information from case notes, descriptive data were summarized by median and interquartile range and proportions in percentage and analyzed by SPSS version 25.
Results: A total of 207 patients who underwent thyroidectomy across the period of study were eligible. Females were 89.37% and% and males 10.63% with a Female: Male ratio 8.4:1. The age of participants ranged from 8 to 81 years, median (IQR) 49 (37-56) years. Malignant lesions 47.83% were papillary carcinoma, 30.43% follicular carcinoma and the rest were squamous cell carcinoma 8.7%,follicular%, follicular variant of papillary thyroid carcinoma 8.7% and 4.35% papillary carcinoma follicular variant.
The study had a sensitivity of 36.36%, specificity 91.89%, positive predictive value of 34.78% negative predictive value 92.39% false positive rate 8.10%, false negative rate 63.64% and an overall accuracy of 85.99%.
Conclusion: This study reveals high specificity, a low sensitivity, and a within range diagnostic accuracy for FNAC at detecting malignancy in thyroid nodules. The findings are a baseline data on performance of FNAC in thyroid tumours at our facility, there is a consistent trend toward papillary thyroid carcinoma (PTC) than follicular thyroid carcinoma (FTC) across regions.