Should we perform fine needle aspiration cytology of subcentimetre thyroid nodules? A retrospective review of local practice

Abstract

In light of the rising rate of incidentally detected subcentimetre thyroid nodules due to improved surveillance and diagnostic imaging, the decision of whether to perform fine needle aspiration cytology is increasingly pertinent. We aim to assess (1) the sampling adequacy of fine needle aspiration cytology, (2) malignancy rate, (3) thyroidectomy rate and (4) diagnostic accuracy of fine needle aspiration cytology. A total of 245 subcentimetre nodules in 220 patients underwent fine needle aspiration cytology between 2011 and 2014. Medical records were reviewed for cytology results, subsequent management and histopathological results in the event the patient underwent thyroidectomy. Sampling adequacy was calculated as the percentage of diagnostic results (Bethesda II-VI). Malignancy rate was defined as the percentage of Bethesda IV-VI diagnoses. Amongst patients with Bethesda IV-VI diagnoses who underwent thyroidectomy, their cytology reports were correlated with post-operative histopathological findings. The sampling adequacy of fine needle aspiration cytology was 77.1%. Malignancy rate (Bethesda IV-VI) was 9.7%. The respective malignancy rates in the < 5 mm nodule group and 5 mm nodule group were 6.67 and 10.0%. In total, 79.2% (19/24) of the malignant nodules underwent surgical excision. The rest declined surgery and/or were lost to follow-up. Amongst the malignant nodules which were surgically resected, 84.2% (16/19) had definitive malignant histology. Five of these demonstrated multifocal carcinoma and/or extrathyroidal extension of carcinoma on histology. Initial fine needle aspiration cytology and subsequent histopathological diagnoses matched in all cases except for three that had false-positive fine needle aspiration cytology results. Majority of our patients with suspicious cytology results subsequently underwent thyroidectomy, notwithstanding the relatively lower diagnostic accuracy of fine needle aspiration cytology in subcentimetre thyroid nodules.

Subcentimetre thyroid nodules: Sonographic features associated with malignancy

“…In addition, patients' concerns and anxiety about the lesions, despite being subcentimetre, may have driven these lesions to be taken up for intervention despite recommendations. This observation of patients' preference for intervention is also evident in previous studies such as Ito et al 25 and Chua et al 22 where up to 80 and 76.6% of patients opted for surgical intervention despite their lack of highly suspicious features or that current guidelines recommended against aggressive intervention of these subcentimetre lesions.…”

“…These differences in the suspicious ultrasound features between subcentimetre and supracentimetre nodules may have contributed to the higher malignancy rates in subcentimetre nodules reported in previous studies. 11,22,23 Given that only hypo-echogenicity and irregular margins were identified as significant features and features of interrupted rim calcification and extrathyroidal extension were rarely observed in our study, subcentimetre nodules may be biased towards a less suspicious classification when evaluated using scoring based systems such as ACR TI-RADS. Subsequently, the subcentimetre nodules for which additional workup may be warranted may not be investigated further under the current ACR TI-RADS guidelines.…”

High-Score US-Suspicious Subcentimeter Thyroid Nodules: What Factors Affect Adequate Sampling of US-Guided Fine-Needle Aspiration Biopsy?

“…Accurate diagnosis is an important step in the management and treatment of these nodules. US-guided FNAB has been a reliable, safe, and cost-effective method for the differential diagnosis of benign and malignant thyroid nodules [1][2][3][4]. e primary purpose of FNAB is to promote the disease management process and determine whether surgery is needed or not.…”

Diagnostic Reliability of the American College of Radiology Thyroid Imaging Reporting and Data System in Royal Commission Hospital, Kingdom of Saudi Arabia

“…The suspicious features of thyroid nodule ultrasound, such as microcalcification, a nodule that is taller than it is wide and speculated or microlobulated margins, are considered to be independent predictors of malignancy in a solid or hypoechoic nodule [9]. However, thyroid fineneedle aspiration cytology (FNAC) remains the gold standard for evaluating thyroid nodular disorders [10]. Sonography-guided thyroid FNAC augments the accuracy and safety of the procedure for assessing thyroid nodules [11].…”