Value of fine-needle aspiration in evaluating large thyroid nodules

Do extremely large goiters carry a higher risk of malignancy or complications? A case control study

INTRODUCTION

The definition of thyroid goiter remains ambiguous, yet size may impact both malignancy rate and surgical complications' rate.

METHODS

All patients with thyroid goiter who underwent thyroidectomy between 1/2015-1/2023 were included. Goiter was defined as lobe ≥4 cm. For analysis purpose, goiters measuring 4-8 cm and ≥8 cm were defined as large and extremely large goiters, respectively. For malignancy definition, tumor<1 cm in their largest diameter were excluded from study. Collected data included demographics, cytology, histology and postoperative complication.

RESULTS

144 goiters from 111 patients were included. The most common indication for surgery was symptoms (55 %). Compared with large goiter, extremely large goiters demonstrated a trend for tracheal narrowing on pre-operative CT findings (23 % vs. 45 %, p = 0.07 respectively). Overall differentiated thyroid carcinoma (DTC) rate was 17 % (25/144) without statistical difference between groups (p = 0.89). Within goiters with pre-operative benign cytology, the DTC rate was 17 % (7/43). Follicular variant of papillary thyroid cancer was the most common type for both groups. Nodular hyperplasia was significantly associated with extremely large goiters (53 % vs. 73 %, p = 0.03). No significant difference was found in transient hypocalcemia (48 % [15/31] vs. 41 % [5/12], p = 0.6) and other complications' rate between extremely large goiters and the control group.

CONCLUSION

When discussing management options for patients with goiters, the size of the goiter should not regarded as a higher risk for complications or malignancy, yet the relatively high malignancy rate found should be taken under consideration for resection.

Risk of malignancy and diagnostic accuracy of fine-needle aspiration biopsy in thyroid nodules with diameters greater than 4 centimeters

Objective

The risk of malignancy and diagnostic accuracy of fine-needle aspiration biopsy (FNAB) of thyroid nodules (TN) with diameters ≥ 3-4 cm remains controversial. However, some groups have indicated surgical treatment in these patients regardless of the FNAB results. We aimed to evaluate the diagnostic accuracy of the FNAB in systematically resected ≥4 cm TN and if the risk of malignancy is higher in these patients.

Subjects and methods

We retrospectively evaluated 138 patients (142 nodules) with TN with diameters ≥4 cm who underwent thyroidectomy.

Results

The FNAB results were nondiagnostic/unsatisfactory (ND/UNS) in 2.1% of the cases and benign in 51.4%. They indicated atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) in 23.9% of cases, follicular neoplasia/suspicious for a follicular neoplasm (FN/SFN) in 9.2%, suspicion of malignancy (SUS) in 8.5%, and malignant in 4.9%. The histopathological analysis after thyroidectomy revealed a thyroid cancer rate of 100% in the FNABs classified as malignant, 33.3% in SUS cases, 7.7% in FN/SFN, 17.6% in AUS/FLUS, and 4.1% in benign FNABs. None of the ND/UNS FNABs were malignant. The global malignancy diagnosis was 14.8% (n = 21). However, the rate of false negatives for FNAB was low (4.1%).

Conclusion

We showed that the risk of malignancy in nodules with diameters ≥4 cm was higher compared to the risk of thyroid cancer in TN in general. However, we found a low rate of false-negative cytological results; therefore, our data do not justify the orientation of routine resection for these larger nodules.

False positive cases in thyroid cytopathology - the experience of a single laboratory and a systematic review

INTRODUCTION

Fine needle aspiration (FNA) is fundamental in the pre-operative assessment of thyroid nodules. However, the shining success of thyroid FNA is occasionally eclipsed by false positive (FP) cytological diagnoses. We describe our experience regarding FP cytological diagnoses and present a literature review concerning FP rates.

MATERIALS AND METHODS

We retrospectively analyzed 2031 consecutive cytology reports. FP was defined as a case with "suspicious for malignancy" or "malignant" cytology, whose surgical follow-up failed to confirm the initial diagnosis of malignancy. We used the PubMed database for the literature review using specific search terms ("thyroid", "cytology", "false positive").

RESULTS

Out of 2031 FNA reports, 93 cases with "suspicious for malignancy" or "malignant" cytology underwent surgical excision. Histopathology did not confirm malignancy in 10 cases (0.6% FP rate). Nodules with FP cytology were significantly larger (P = 0.0024) than those with with TP (true positive) cytology. A review of 25 publications shows comparable results to ours with some slight differences. The majority of studies achieve a FP rate below 3%. Most FP cytological diagnoses turn out to be non-neoplastic lesions (nodular hyperplasia, adenomatous nodule, lymphocytic thyroiditis), which combined account for 80.5% of all histological diagnoses.

CONCLUSIONS

Thyroid nodules with FP cytology were larger than nodules with TP cytology. Most studies manage to adhere to the recommended FP rates, or values close to them, with some outliers. Nevertheless, the mean FP rate values are very close to the value recommended by The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). The FP rate value depends on how one defines true negative cases, which can be either histologically proven benign cases, via a benign clinical course, or by assuming that cytologically benign cases remain as such.

Large Cytologically Benign Thyroid Nodules Do Not Have High Rates of Malignancy or False-Negative Rates and Clinical Observation Should be Considered: A Meta-Analysis

Background: Management of large thyroid nodules is controversial, as data are conflicting regarding overall rates of malignancy (ROM) in all nodules and frequency of false-negative fine-needle aspiration results (FNR) in cytologically benign nodules. This meta-analysis aimed to evaluate and compare ROM and FNR in small versus large nodules published in the literature. Methods: Articles indexed in PubMed, written in English, published electronically or in print on or prior to December 8 2017 were searched for "false negative thyroid size or cm" and "malignancy rates benign thyroid nodules." Three hundred fifty-two unique citations were identified. Multiple reviewers selected a final set of 35 articles that contained nodules stratified by size (3, 4, or 5 cm), with benign or all cytologic diagnoses, and with postsurgical histologic diagnoses. Multiple observers extracted data, including numbers of total, cytologically benign, and histologically malignant nodules. Size cutoffs of 3, 4, and/or 5 cm were analyzed in 14, 24, and 1 article, respectively. Results: ROM in all nodules ≥3 cm (13.1%) and ≥4 cm (20.9%) was lower than those <3 cm (19.6%) and <4 cm (19.9%; odds ratio [OR] = 0.72 [confidence interval (CI) 0.64-0.81] and OR = 0.85 [CI 0.77-0.95]). FNR in nodules ≥3 cm (7.2%) was not different from smaller nodules (5.7%; OR = 1.47 [CI 0.80-2.69]). FNR in nodules ≥4 cm (6.7%) was slightly higher than those <4 cm (4.5%; OR = 1.38 [CI 1.06-1.80]). The most frequently reported false-negative diagnosis was papillary thyroid carcinoma. Conclusions: Rates of malignancy and false-negative FNA results vary but, in most studies, are not higher in larger nodules. Patients with large, cytologically benign thyroid nodules need not undergo immediate surgical resection, as false-negative FNA rates are low and are expected to decrease in light of nomenclature revision of a subset of follicular variants of papillary thyroid carcinoma.