The endocrinologists' view of ultrasound guidelines for fine needle aspiration

The Bethesda System for Reporting Thyroid Cytology (TBSRTC): From look-backs to look-ahead

The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) was formalized in October 2007 by experts in thyroidology at the National Institute of Health in Bethesda, Maryland. The first edition of the TBSRTC book was published in 2010 and the second edition in 2018. The TBSRTC is widely employed in cytology practices in the United States and has also served as a model for similar tiered classification schemes for reporting thyroid cytopathology specimens. The tremendous success of TBSRTC cannot be underscored, it has provided a diagnostic framework which is well aligned with the present and the future of thyroid nodule management.

Fine needle aspiration cytology guided by ultrasound in the diagnosis of subcentimetre thyroid nodules

Background

This study aimed to investigate the value of fine needle aspiration biopsy (FNAB) under ultrasound guidance in diagnosis of thyroid nodules. In a retrospective analysis of FNAB in 1050 cases of patients with 1100 nodules, patients were divided according to the maximum diameter of their nodules into two groups: >1.0 and ≤1.0 cm. The ultrasound-guided FNAB cytology results were compared between two groups.

Results

Ultrasound findings showed that among 1100 thyroid nodules, 547 were highly suspicious, 358 were moderately, 175 were low, and 19 were very low. Cytology results showed papillary carcinomas in 453, possible papillary cancer in 126 cases, follicular tumors in 26, suspicious follicular tumors in 6, atypical cells in 7, nodular goiter in 289, colloid in 13, chronic lymphocytic thyroiditis in 175, and undiagnosed specimen in 5. Ultrasound diagnosis of thyroid nodules had an overall sensitivity of 86.0 %, and a specificity of 81.9 %. In nodules larger than 1.0 cm, the sensitivity was 92.8 %, and the specificity 92.3 %. In nodules ≤1.0 cm, the sensitivity was 82.4 %, and the specificity was 81.7 %.

Conclusions

Patients with highly suspicious thyroid nodules on ultrasonography, regardless of nodule sizes, should receive ultrasound-guided FNAB to confirm their natures and direct clinical managements.

A Review on Ultrasound-Based Thyroid Cancer Tissue Characterization and Automated Classification

In this paper, we review the different studies that developed Computer Aided Diagnostic (CAD) for automated classification of thyroid cancer into benign and malignant types. Specifically, we discuss the different types of features that are used to study and analyze the differences between benign and malignant thyroid nodules. These features can be broadly categorized into (a) the sonographic features from the ultrasound images, and (b) the non-clinical features extracted from the ultrasound images using statistical and data mining techniques. We also present a brief description of the commonly used classifiers in ultrasound based CAD systems. We then review the studies that used features based on the ultrasound images for thyroid nodule classification and highlight the limitations of such studies. We also discuss and review the techniques used in studies that used the non-clinical features for thyroid nodule classification and report the classification accuracies obtained in these studies.

Current role and value of fine-needle aspiration in nodular goitre

Thyroid nodules are common and, depending on the detection technique used, can affect 50% or greater of the population. The primary diagnostic test to assess the nature of these nodules is fine-needle aspiration cytology. Most thyroid nodules are benign and often are multiple. However, the morphology of these nodules may mimic neoplasms showing features such as papillary growth, micro-follicles and even oncocytic metaplasia. Lesions with these features may be considered indeterminate for neoplasm or malignancy, and often require surgical excision to define their nature. The role of cytopathology in this area is to screen those definitely benign nodules, thus preventing surgery and reassuring both the patient and the clinician. In this review, we demonstrate many of the morphological manifestations of nodular goiter and stress the necessity of careful preparatory techniques. Although the past several years have witnessed the development of molecular testing to refine diagnostic cytology in the thyroid, it is still the role of the cytopathologist to identify those "indeterminant" nodules which should be tested. Thus, the cytopathologist contributes both an essential diagnostic and an important cost saving role which hopefully will continue in the future.

Ultrasound-guided fine-needle aspiration biopsy in unselected consecutive patients with thyroid nodules

The objective was to analyze the results of UG-FNAB, performed in unselected consecutive patients with thyroid nodules. Methods. The UG-FNAB records were analyzed in this retrospective study. Indication for biopsy was the presence of at least one nodule detected by ultrasound. Results. 330 patients at mean age ± SD 48.4 ± 11.2 years; women/men = 12.8/1 were analyzed. From the total 596 nodules found 546 (91.6%) were investigated with 1231 punctures (2.3 per nodule and 3.7 per patient). Benign solitary nodules had 42.7%, multinodular goiter (MNG) 44.8%, inconclusive 4.8%, and others 2.1% and malignant nodules 5.5% of the patients (6.6% of solitary and 5.1% of MNG patients). The risk for a separate nodule in MNG to be malignant was 2.7%. Conclusions. UG-FNAB is a safe and reliable diagnostic approach for thyroid nodules. It is the method of choice for hypo- and isoechoic not purely cystic solitary nodules, regardless of the nodule size. In MNG, its positive predictive value and diagnostic accuracy are lower. The final decision for regular US monitoring, UG-FNAB of the dominant nodule, multipuncture UG-FNAB or surgical exploration is one of complex appraisal. We consider UG-FNAB appropriate for most nodules in MNG, according to the above mentioned criteria.

Enlarged benign-appearing cervical lymph nodes by ultrasonography are associated with increased likelihood of cancer somewhere within the thyroid in patients undergoing thyroid nodule evaluation

BACKGROUND

Benign-appearing cervical lymph nodes (CLN) are easy to assess during an ultrasonography (US) evaluation for a guided fine-needle aspiration biopsy of a suspicious thyroid nodule, but their clinical significance regarding thyroid cancer risk is not known. Non-malignant-appearing nodes may be an indicator of early malignancy in the thyroid. We hypothesize that there is an increased prediction of thyroid cancer when benign-appearing enlarged CLN (ECLN) > 1 cm in any dimension are present during an US evaluation of thyroid nodules.

METHOD

A review of 269 consecutive patients' charts sent for thyroid nodule assessment that underwent thyroidectomy was conducted to compare ECLN, with the presence of thyroid cancer during an ultrasound-guided fine-needle aspiration biopsy of the thyroid nodule. Surgical excision pathology confirmed all abnormal cytology reports.

RESULTS

From the final 265 charts reviewed, 213 had benign thyroid pathology and 52 had thyroid cancer. Sex, number, and size of the biggest thyroid nodule were not different between groups. Patients with cancer were on average 10 years younger and had higher thyroid-stimulating hormone (TSH) values (p < 0.003) as well as a 10-fold increase in enlarged non-malignant-appearing lymph nodes than their peers without cancer. The presence of ECLN had an 82% sensitivity, 90% specificity, and a 68% positive predictive value for thyroid cancer. There was also an 80% negative predictive value when enlarged lymph nodes were not present. In 8 of the 37 (21.6%) patients with malignancy and ECLN, the primary dominant thyroid nodule was negative on cytologic evaluation, but malignancies were confirmed on surgical specimen, in contralateral nodules on the same side as the ECLN. These nodules were mostly subcentimeric, ranging from 0.2 to 1.14 cm and were not biopsied due to their inconspicuous appearance. After multiple logistic regression analysis, enlarged lymph nodes had a 53.8 odds ratio for cancer (20.49-141.33, p < 0.01).

CONCLUSION

Discovering the presence of ECLN in routine assessment of thyroid nodules is an easy and fast surveillance technique that increases the predictive value in diagnosing thyroid cancer, especially when the enlarged lymph nodes are on the same side as the thyroid nodule.

Ultrasound-guided fine-needle aspiration biopsy of thyroid nodules smaller than 5 mm in the maximum diameter: assessment of efficacy and pathological findings

Objective

The aim of this study was to determine the efficacy of the use of an ultrasound-guided fine-needle aspiration biopsy (US-FNAB) to diagnose thyroid nodules smaller than 5 mm in the maximum diameter and to evaluate pathological findings of small thyroid malignancies.

Materials and Methods

From May 2007 to April 2008, we evaluated the findings of US-FNABs of small thyroid nodules less than 5 mm in the maximum diameter. The cytopathological findings were retrospectively reviewed and the diagnostic performance of the use of an US-FNAB was examined in all patients.

Results

Of 201 small thyroid nodules in 180 patients, there were 162 adequate specimens (81%). Among 180 patients, 75 patients underwent thyroid surgery and 50 malignant and 33 benign nodules were identified based on a pathological examination. All small malignant thyroid nodules were identified as papillary thyroid microcarcinomas (PTMCs). There were 34 (55%) true positive, 0 (0%) false positive, 23 (37%) true negative and five (8%) false negative results for malignancy after performing a first US-FNAB in 62 surgically confirmed nodules. The sensitivity (87%), specificity (100%), positive predictive value (100%), negative predictive value (82%), accuracy (92%), false positive rate (0%) and false negative rate (8%) for an US-FNAB were determined. In 23 patients with a primary PTMC, capsular invasion (9%, 2 of 23), a perithyroidal lymph node metastasis (30%, 7 of 23), the rate of multifocality (9%, 2 of 23) and bilaterality (4%, 1 of 23) were also determined.

Conclusion

An US-FNAB of thyroid nodules smaller than 5 mm in the maximum diameter is an effective diagnostic procedure.

Fine-needle aspiration of the thyroid: today and tomorrow

This review describes the morphological features of the common thyroid lesions that are sampled by fine-needle aspiration (FNA), including hyperplastic (adenomatous, adenomatoid) nodules, inflammatory and autoimmune conditions (lymphocytic thyroiditis), and benign and malignant neoplasms. For the last category of lesions, the cytological features are described and the differential diagnoses are discussed. Finally, an assessment of modern techniques such as immunohistochemistry and molecular analyses is given with emphasis on their validity for FNA samples as well as the pitfalls that are encountered in their use.

Decision analysis of discordant thyroid nodule biopsy guideline criteria

CONTEXT

Recently published guidelines are discordant regarding diagnostic approaches to small (10-14 mm) thyroid nodules.

OBJECTIVE

The objective of the study was to explore the relative desirability of alternative diagnostic approaches to small thyroid nodules using decision analysis.

DESIGN

Four diagnostic approaches to a 10- to 14-mm thyroid nodule are modeled: 1) observation only, consistent with American Thyroid Association guidelines; 2) routine fine-needle aspiration biopsy (FNAB), an approach traditionally chosen by many endocrinologists and consistent with American Thyroid Association guidelines; 3) FNAB only when microcalcifications are present, as recommended by Society of Radiologists in Ultrasound guidelines; and 4) FNAB only when the nodule is hypoechoic and has at least one other ultrasonographic risk factor, as endorsed by American Association of Clinical Endocrinologists guidelines.

MAIN OUTCOME MEASURES

Measures included expected values; a priori likelihoods of prespecified outcomes; and two-way sensitivity analyses based on the utility of observation only in the setting of thyroid cancer and thyroid surgery for benign, asymptomatic thyroid disease.

RESULTS

Expected values (EVs) were similar among decision alternatives modeling Society of Radiologists in Ultrasound guidelines, American Association of Clinical Endocrinologists guidelines, and routine observation (EVs from 0.912 to 0.927). Routine FNAB had the lowest EV (0.757-0.861), primarily related to a high a priori likelihood of having surgery for a benign nodule.

CONCLUSIONS

As a general approach to 10- to 14-mm thyroid nodules, routine FNAB appears to be the least desirable. This analysis offers additional data that physicians can use when choosing diagnostic approaches to small thyroid nodules based on perceived risks of delayed cancer diagnosis and unnecessary thyroid surgery.

High prevalence of carcinoma in ultrasonography-guided fine needle aspiration cytology of thyroid nodules

OBJECTIVE

The purpose of this study was to assess the rate of malignancy in thyroid nodules incidentally detected at sonography and to determine the diagnostic value of ultrasonography-guided fine needle aspiration cytology (USgFNAC) in thyroid nodules.

METHODS

Five hundred patients (84 men and 416 women) who had thyroid incidentalomas underwent USgFNAC at Konkuk University Hospital between August 2005 and July 2006. Thyroid sonography and guided aspiration was performed on all single nodules and on dominant nodules with suspected malignancy in cases of multinodular goiter.

RESULTS

Five hundred fifty-eight nodules from 500 patients were aspirated using ultrasonography guidance. The USgFNAC results for all patients were as follows: 307 (61.4%) benign, 108 (21.6%) suggestive of malignancy, 56 (11.2%) indeterminate, and 29 (5.8%) inadequate for cytologic diagnosis. The rate of malignancy was significantly higher in women than in men (23.6% in women vs 11.9% in men, p<0.01). Ultrasonographic characteristics that had a significant association with thyroid malignancy included solid echocomponent, hypoechogenecity, ill defined margin, and presence of microcalcifications (p<0.05). Eighty-eight patients underwent surgical resection. The positive predictive value of USgFNAC was 90.2% (74/82), and the accuracy index was 84.1% (74/88). In 80 patients with well-differentiated thyroid carcinoma after surgery, 49% (39/80) had lesions smaller than 1 cm.

CONCLUSION

The rate of malignancy in incidental thyroid nodules on USgFNAC was 21.6%. Ultrasonographic features could be useful in differentiating between benign and malignant nodules.

Radiologic and pathologic findings of nonpalpable thyroid carcinomas detected by ultrasonography in a medical screening center

OBJECTIVE

The purpose of this study was to investigate the ultrasonographic and pathologic findings of nonpalpable thyroid carcinomas and reliable guidelines for fine-needle aspiration (FNA).

METHODS

Our study was approved by our Institutional Review Board, and written informed consent was waived. Between April 2004 and June 2006, screening ultrasonography was performed for 16,352 self-referred patients in the health care center. Among 1325 nonpalpable thyroid nodules in 1009 patients, pathologic results of FNA revealed 823 benign, 154 indeterminate, 198 nondiagnostic, and 150 malignant nodules. Fifty-eight malignant thyroid nodules (39 microcarcionomas and 19 carcinomas >1 cm, confirmed by both FNA and thyroidectomy) in 55 patients and 82 benign nodules (confirmed by both FNA and follow-up over 2 years) in 75 patients were included for the analysis. Three radiologists retrospectively analyzed the ultrasonographic features of these nonpalpable thyroid nodules for echogenicity, shape, margin, calcification, degree of cystic changes, and size. We compared the radiologic and pathologic findings between microcarcinomas and carcinomas larger than 1 cm for extra-capsular invasion, lymph node metastasis, bilaterality, and multicentricity using univariate analysis.

RESULTS

Marked hypoechogenicity, an irregular shape, a taller-than-wide shape, a well-defined spiculated margin, microcalcification, and an entirely solid nature were significant predictors for malignancy (P < .05), whereas a cutoff value of 1 cm in the longest diameter was not significant (P = .184). However, extracapsular invasion (P = .024) and lymph node metastasis (P = .019) were observed more frequently in carcinomas larger than 1 cm (73.7% and 42.1%, respectively) than in microcarcinomas (38.5% and 12.8%).

CONCLUSIONS

Ultrasonographic findings suggesting malignancy should be preferentially considered as indicators for FNA, regardless of size, in nonpalpable thyroid nodules. However, extracapsular invasion and lymph node metastasis are closely related to the size of the thyroid nodule.

Concordance between thyroid nodule sizes measured by ultrasound and gross pathology examination: Effect on patient management

Ultrasound examination (US) is an essential tool in the evaluation of thyroid nodules. The size determined by US is used to distinguish between clinical vs. nonclinical thyroid nodules i.e. greater than or equal to or less than 1 cm. In this study, we evaluated the concordance between the sizes of thyroid nodules measured by US and by gross examination after thyroidectomy. This study included 664 nodules that underwent fine-needle aspiration (FNA) and subsequent excision in 621 patients; 580 had single and 41 patients had multiple (39 with 2, and 2 with 3 nodules) nodules. Both US and gross pathology measurements were taken in three dimensions. The nodule sizes as measured by US were stratified into five groups: A: <or=1.0 cm, B: 1.1-2.0 cm, C: 2.1-3.0 cm, D: 3.1-5.0 cm, and E: >or=5.1 cm. FNA diagnoses were categorized into: Benign (n = 59), Neoplastic / Indeterminate (n = 342), Suspicious (n = 123), Malignant (n = 106), and nondiagnostic (n = 34). Upon excision 278 (42%) nodules were classified as malignant and 386 (58%) as benign. In group A the concordance between US and excisional size was 78.5%, group B 56%, group C 34.5%, group D 40% and group E 52.5%. Only 14 (14/664 2%) nodules measured <or=1.0 cm by US, however, after thyroidectomy 105 (105/664 15.5%) measured <or=1.0 cm in size. Histological diagnoses of this group were benign 62 (58%), papillary microcarcinoma 39 (37%), medullary microcarcinoma 3 (3%) and follicular/Hurthle cell carcinoma 2 (2%) cases. In this study the concordance in benign or malignant nodules measured by US and surgical pathology examination is <or=50%, except in the <or=1.0 cm size range (78.5%). This may lead to an increase in the number of patients undergoing FNA and subsequent surgical excision.

Progress in the preoperative diagnosis of thyroid nodules: managing uncertainties and the ultimate role for molecular investigation

The preoperative evaluation of thyroid nodules currently relies on a clinical assessment of risk factors and an algorithm based on imprecise tests. With serum TSH, thyroid ultrasound and fine-needle aspiration (FNA) with or without ultrasound guide, accounting for the routine initial evaluation, indeterminate aspirates remain the major obstacle for confidently advising patients whether to have surgery or not. Recent clinical guidelines have attempted to settle various controversies but many inherent errors of clinical testing result in delayed diagnosis and unnecessary surgery. A better solution may ultimately involve the use of molecular markers of thyroid carcinogenesis but further research is still needed regarding the basic biology of thyroid cancer.