A retrospective study correlating sonographic features of thyroid nodules with fine-needle aspiration cytology in a South African setting

Abstract

BackgroundThyroid nodules are prevalent worldwide. Detection rates are increasing because of the use of ultrasonography. Ultrasound has become the first-choice imaging modality in evaluating nodules. The decision to perform an US-guided fine-needle aspiration (FNA) is based on a nodule’s sonographic features. Thus, it is essential to accurately risk stratify thyroid nodules so that they are appropriately referred for FNA.ObjectivesThe aim of this study was to correlate the ultrasound imaging features of thyroid nodules with FNA cytology and surgical histopathology results, and to risk stratify patients using the American Thyroid Association (ATA) classification for each imaging characteristic with the likelihood of the nodule being malignant.MethodRetrospective analysis of a thyroid ultrasound database at Chris Hani Baragwanath Academic Hospital, over the period 2015–2017. Frequencies and percentages were used to summarise the data. Univariate logistic regression analyses were used to assess the accuracy of sonographic features in predicting the histologically determined diagnosis for thyroid tumours.ResultsA total of 113 nodules underwent FNA, of which 104 were diagnostic. The best three ultrasound features that pose a higher risk for malignancy are absent halo, presence of microcalcifications and hypoechoic appearance. No single nodule feature is an absolute indicator for malignancy. There is a high agreement between ATA classification and cytopathology or histology when nodule features are grouped into clusters. Agreement between the ATA classification and cytopathology/histology was 86.7% with a kappa of 0.714. The agreement between the cytopathology FNA results and lobectomy histopathology was 98.8% with a kappa of 0.973.ConclusionThis study contributes to the paucity of data available for sub-Saharan Africa and provides reassurance that our results are consistent with international studies. The study confirms that the usage of a thyroid nodule classification system improves characterisation and increases accuracy in detecting thyroid malignancies, thus sparing many patients the morbidity of unnecessary thyroid surgery.

Epidemiological, Clinical, Ultrasonographic and Cytological Characteristics of Thyroid Nodules in an Afro-Caribbean Population: A Series of 420 Patients

“…This may be due to the small cancer sample in our study. Hypoechogenicity was frequently found in malignant nodules, in agreement with the literature [2,33,34]. However, we did not find the irregular contour parameter as a predictive factor for thyroid cancer [33].…”

The combination of ATA classification and FNA results can improve the diagnostic efficiency of malignant thyroid nodules

“…Recent studies have indicated that no single ultrasound feature can directly and accurately predict the malignancy of a nodule ( 36 , 37 ); however, some characteristics, such as hypoechogenicity, irregular margins, taller-than-wide shape, microcalcifications and solidity, may predict thyroid cancer ( 14 , 16 , 17 , 19 , 20 , 38 ). In this study, solidity, hypoechogenicity, irregular margins, taller-than-wide shape, microcalcifications and posterior echo attenuation associated with malignant nodules, whereas regular halo associated with benign nodules.…”

Impact of a multidisciplinary approach to ultrasound- guided thyroid fine-needle aspiration biopsy at Tygerberg Hospital, Cape Town, South Africa: A retrospective audit

“…The most significant impact is noted in centres with a high rate of non-diagnostic reports. [8][9][10][11] The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) has resolved adequacy threshold issues for pathologists. [6,12] It was implemented at the TBH cytology laboratory and has been used since 2016.…”