Ultrasound‐guided fine‐needle aspiration or core needle biopsy for diagnosing follicular thyroid carcinoma?

Abstract

Objective:We evaluated the preoperative diagnostic values of ultrasound (US), fineneedle aspiration (FNA) and core needle biopsy (CNB) leading to surgery in patients with FTC. Methods:From October 1994 to July 2016, 298 patients with FTC who had preoperative US images and underwent US-guided FNA or CNB and surgery were included in this study. We evaluated the results of preoperative FNA or CNB based on the Bethesda system and the US findings according to the Korean thyroid imaging reporting and data system (K-TIRADS). Results:Predominant US features of FTC showed solid, hypo-or iso-echogenicity, oval smooth margin and halo with no calcification. Based on K-TIRADS, 140 (47.0%) patients with FTC were categorized as low suspicion, 133 (44.63%) as intermediate suspicion and 25 (8.4%) as high suspicion at US. Considering only FNA cytology (n = 230), 6.9% were revealed as Bethesda class I, 16.1% as class II, 37.0% as class III, 29.1% as class IV and 10.9% as class V. Considering the 68 cases with CNB results, 2.9% were revealed as class I, 4.4% as class II, 20.6% as class III and 72.1% as class IV. Despite multiple FNAs, 16.7% of the 84 patients with FTC still obtained Bethesda class I or class II. CNB results in patients with FTC had a significantly higher rate of Bethesda class IV compared to the FNA results (P < .001). FTCs with distant metastasis exhibited a significantly higher rate of Bethesda classes IV and V compared to those without distant metastasis (P = .004). Conclusion:Surgery for FTC is deferred only with preoperative US and FNA. CNB in patients with FTC can lead to surgery better than FNA. Therefore, if the US feature is characteristic and a serially growing large nodule is suspected, the first attempt of CNB may be helpful in selecting a surgical candidate. K E Y W O R D S core needle biopsy, fine-needle aspiration, follicular thyroid carcinoma, thyroid neoplasm, ultrasonography | 469 PARK et Al.

Diagnostic performance of core needle biopsy as a first‐line diagnostic tool for thyroid nodules according to ultrasound patterns: Comparison with fine needle aspiration using propensity score matching analysis

“…However, most FTC and many of follicular variant PTC show low or intermediate suspicion US patterns 2,17,37 . This result may explain the lower sensitivity of FNA for malignancy in the K‐TIRADS 3/4 nodules compared to the K‐TIRADS 5 nodules as FNA has a lower sensitivity and a relatively high false‐negative rate for FTC and follicular variant of PTC 2,37 . Meanwhile, CNB showed a similarly high sensitivity for malignancies with criterion 3 in both K‐TIRADS 3/4 and K‐TIRADS 5 nodules in our study, which suggests that malignant tumours with K‐TIRADS 3/4 US patterns can be effectively detected by CNB with criterion 3.…”

“…Although our study showed that CNB was superior to FNA in the diagnosis of malignancy in K‐TIRADS 3/4 nodules, there are several issues to be considered. First, the sensitivity of CNB for follicular neoplasms and FTC was substantially higher, and false‐negative rates of benign CNB results for FTC were lower than FNA, which can be explained by the advantage of CNB in providing better information on architectural histologic features and nodule capsule 2,34 . Therefore, CNB may be superior to FNA for the diagnosis of follicular neoplasms and FTC.…”

“…Therefore, CNB may be superior to FNA for the diagnosis of follicular neoplasms and FTC. Meanwhile, CNB may increase the diagnosis of follicular adenomas as well as FTC, 2,34 and surveillance instead of immediate surgery may be considered for small nodules less than 2 cm diagnosed as follicular neoplasms. Second, although CNB reduced the number of inconclusive results compared to FNA in low/intermediate suspicion nodules in our study, a wide range (4.6‐16.5%) of the AUS/FLUS result rate has been reported in the first‐line use of CNB 11,13,15,35 .…”

“…Our study and previous study 17 demonstrated that the majority of PTC showed a high suspicion US pattern. However, most FTC and many of follicular variant PTC show low or intermediate suspicion US patterns 2,17,37 . This result may explain the lower sensitivity of FNA for malignancy in the K‐TIRADS 3/4 nodules compared to the K‐TIRADS 5 nodules as FNA has a lower sensitivity and a relatively high false‐negative rate for FTC and follicular variant of PTC 2,37 .…”

“…Although ultrasound (US)‐guided fine‐needle aspiration (FNA) is the standard diagnostic tool for thyroid nodules, FNA has a relatively high rate of inconclusive results 1 and relatively low diagnostic accuracy for follicular thyroid carcinomas (FTC) and uncommon malignant tumours, such as lymphoma, anaplastic carcinoma, medullary carcinoma and metastasis 2‐6 . US‐guided core‐needle biopsy (CNB) has been reported as an effective and safe diagnostic technique for thyroid nodules 7,8 .…”