Abstract
A primary medical relevance of thyroid nodules consists of excluding thyroid cancer, present in approximately 5% of all thyroid nodules. Fine-needle aspiration biopsy (FNAB) has a paramount role in distinguishing benign from malignant thyroid nodules due to its availability and diagnostic performance. Nevertheless, intraoperative frozen section (iFS) is still advocated as a valuable tool for surgery planning, especially for indeterminate nodules. To compare the FNAB and iFS performances in thyroid cancer diagnosis among nodules in Bethesda Categories (BC) I to VI. The performance of FNAB and iFS tests were calculated using final histopathology results as the gold standard. In total, 316 patients were included in the analysis. Both FNAB and iFS data were available for 272 patients (86.1%). The overall malignancy rate was 30.4%% (n = 96). The FNAB sensitivity, specificity, and accuracy for benign (BC II) and malignant (BC V and VI) were 89.5%, 97.1%, and 94.1%, respectively. For all nodules evaluated, the iFS sensitivity, specificity, and accuracy were 80.9%, 100%, and 94.9%, respectively. For indeterminate nodules and follicular lesions (BC III and IV), the iFS sensitivity, specificity, and accuracy were 25%, 100%, and 88.7%, respectively. For BC I nodules, iFS had 95.2% of accuracy. Our results do not support routine iFS for indeterminate nodules or follicular neoplasms (BC III and IV) due to its low sensitivity. In these categories, iFS is not sufficiently accurate to guide the intraoperative management of thyroidectomies. iFS for BC I nodules could be an option and should be specifically investigated.
Highlights
Thyroid nodules are common and can be detected by ultrasound (US) in 50%-60% of adults [1]
Due to its diagnostic performance and wide availability, the cytological analysis of the material obtained by fine-needle aspiration biopsy (FNAB) has a paramount role in distinguishing benign from malignant thyroid nodules [6]
From 2015 to 2018, a total of 346 thyroidectomies due to nodular disease were performed in the Hospital de Clínicas de Porto Alegre (HCPA)
Summary
Thyroid nodules are common and can be detected by ultrasound (US) in 50%-60% of adults [1]. FNAB has an intrinsic limitation to establish the diagnosis of follicular or Hürthle malignant cell lesions, as the demonstration of capsular or vascular invasion is required to distinguish benign from malignant non-papillary thyroid tumors [7,8]. In this context, intraoperative frozen section (iFS) has been historically advocated as an essential tool in defining the extent of thyroid surgery (total vs partial thyroidectomy). Many surgical teams still consider iFS as a useful tool to optimize the decision regarding the extent of surgery, especially for indeterminate nodules (Bethesda Categories III or IV), which represent approximately 20% of all thyroid FNAB and associated with a malignancy risk of 5%30% [8-10]. All tests were two-tailed, and a P < 0.05 was considered statistically significant
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