Fine-needle aspiration diagnosis of the follicular variant of papillary carcinoma

Efficacy of Follicular Cell Pattern Analysis in Thyroid Fine-needle Aspiration Cytology Evaluation

CONTEXT

Fine-needle aspiration cytology (FNAC) is widely utilized for thyroid lesion diagnosis but faces challenges such as sample inadequacy and overlapping cytological features. This study examines how accurately these patterns correlate with histopathological diagnoses, shedding light on FNAC's limitations and diagnostic potential.

AIMS

To study the application of the architectural pattern of follicular cells in the interpretation of thyroid lesions and to demonstrate the diagnostic accuracy (DA) of FNAC.

SETTINGS AND DESIGN

Cross-sectional study carried over 1 year.

SUBJECTS AND METHODS

A total of 110 cases were reviewed by the cytopathologists. The prominent follicular cell architecture, namely macrofollicular, microfollicular, papillary, trabecular, three-dimensional clusters, and dispersed cells, was described in each case. In addition to these patterns, cellular morphology and background features were also noted, and a final cytological diagnosis was established. The cytology diagnosis was correlated with the histopathological diagnosis.

STATISTICAL ANALYSIS USED

Sensitivity, specificity, positive predictive value, negative predictive value, DA of FNAC in diagnosing nonneoplastic and neoplastic lesions.

RESULTS

Macrofollicular pattern was seen in 80.26% of colloid goiter cases. Microfollicular pattern was observed in 72.2% of follicular neoplasm. About 62.5% of papillary thyroid carcinomas showed a papillary pattern. The trabecular pattern was seen in 42.86% of chronic lymphocytic thyroiditis and 16.67% of follicular neoplasms. The sensitivity and specificity of FNAC in diagnosing neoplastic lesions was 92.59% and 97.59%, respectively.

CONCLUSIONS

FNAC is a simple, rapid, definite, and cost-effective primary diagnostic tool for thyroid evaluation. Cell architecture pattern is a simple and appropriate approach that complements cell morphology and background details in arriving at the final cytological diagnosis of thyroid lesions.

Clinicopathological parameters for predicting non-invasive follicular thyroid neoplasm with papillary features (NIFTP)

BACKGROUND

Criteria for the preoperative diagnosis of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) have not yet been confirmed. This study aimed to analyze differences in clinicopathological characteristics between follicular variant of papillary thyroid carcinoma (FVPTC) subtypes to determine which parameters are relevant in differentiating NIFTP from other variants.

METHODS

We retrospectively analyzed the records of 199 patients with a preoperative diagnosis of FVPTC who underwent thyroid surgery at Seoul St. Mary's Hospital (Seoul, Korea) from 2011 to 2015. Clinicopathological features were analyzed retrospectively via a complete review of medical charts and pathology reports of patients.

RESULTS

The NIFTP and invasive encapsulated FVPTC (EFVPTC) groups showed relatively benign features, with a majority of the patients categorized as Bethesda category III (25.8% and 25.6%, respectively) or IV (34.8% and 30.2%, respectively), while the infiltrative FVPTC group showed more malignant features, with more patients categorized as category V (28.6%) or VI (47.6%) (p < 0.001). BRAF ^V600E mutations were significantly less prevalent in the NIFTP group (0%) and invasive EFVPTC group (4.7%) compared with the infiltrative FVPTC group (34.9%) (p < 0.001). Multivariate analysis showed that absence of BRAF ^V600E mutation (OR 20.311, p = 0.004) and lymph node metastasis (odds ratio 10.237, p = 0.004) were significantly associated with NIFTP.

CONCLUSION

Although Bethesda category was a statistically significant factor in distinguishing FVPTC subtypes, it was not effective in conclusively distinguishing NIFTP and invasive EFVPTC. Absence of BRAF ^V600E mutation and lymph node metastasis are important features in distinguishing NIFTP from other subtypes.

Does noninvasive follicular thyroid neoplasm with papillary-like nuclear features have distinctive features on sonography?

BACKGROUND

The noninvasive encapsulated follicular variant of papillary carcinoma (nEFVPTC) has recently been reclassified to "noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP)," removing this entity from the malignant category. This re-categorization has had major implications for clinical management. NIFTP has overlapping cytohistologic features with papillary thyroid carcinoma (PTC) and with follicular adenomas (FA), but sonographic data comparing NIFTP to PTC and FA is lacking. Our study examines the sonographic features of NIFTP as compared with PTC and FA.

METHODS

Ultrasound scans and Doppler blood flow from subjects who had pre-surgical sonograms and fine needle aspiration biopsies with final surgical pathology diagnoses of NIFTP/nEFVPTC, classical PTC, and FA between 01/2013-08/2016 were assessed. Sonographic and Doppler features as well as Bethesda System (TBS) diagnoses were recorded and analyzed.

RESULTS

40 NIFTP, 58 classical PTC, and 23 FA cases were included. The most common NIFTP pre-surgical TBS cytology diagnosis was Atypia of Undetermined Significance (AUS/FLUS) (40%). NIFTP cases predominantly displayed wider-than-tall shape (100%), smooth borders (75%), occurrence in multinodular glands (82.5%), heterogeneous echogenicity (50%), both perinodular and intranodular Doppler flow patterns (70%), minimal Doppler flow grade (62.5%), and no calcifications (90%).

CONCLUSIONS

Our study demonstrates that NIFTP, PTC, and FA display several distinguishing and overlapping sonographic and Doppler features. Sonographic features appear to complement cytology findings and may help raise pre-operative concern for NIFTP in the proper clinical setting, potentially leading to a more conservative management approach.

Preoperative differentiation between noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) and non-NIFTP

BACKGROUND

A recent concept was proposed that the noninvasive encapsulated follicular variant of papillary thyroid carcinoma reclassified as "noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP)" is benign. Our aim was to identify the differences between NIFTP and non-NIFTP preoperatively.

METHODS

This retrospective study included a total of 208 patients with 208 follicular variant of papillary thyroid carcinomas (FVPTC) that were surgically confirmed at three university hospitals from 2008 to 2014. Clinical factors, the biopsy techniques and ultrasonography (US) imaging characteristics were compared between the NIFTP and non-NIFTP groups.

RESULTS

A total of 34 NIFTP (16·3%) and 174 non-NIFTP (83·7%) were observed. For NIFTPs, the need for surgery was indicated by ultrasonography-guided fine needle aspiration (US-FNA) in 54·3% and by ultrasonography-guided core needle biopsy (US-CNB) in 100% (P = 0·008). For non-NIFTP, no significant difference was noted in the rates of surgical indication between US-FNA and US-CNB (62·6% vs 78·9%, P = 0·054). The most common biopsy diagnosis of NIFTP was Bethesda category V (28·6%) in the US-FNA group and category IV (45·5%) in the US-CNB group. US diagnosis of NIFTP had a significantly lower rate of the high suspicion of malignancy than that of non-NIFTP (14·7% vs 37·9%, P = 0·024). Central nodal metastasis was found in only one case (2·9%) of NIFTP patients, but none had distance metastasis or recurrence.

CONCLUSION

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features lacks malignant US features and is better triaged using US-CNB than using US-FNA to facilitate the surgical management. US evaluation is pivotal in determining the next step of FVPTC management.

Follicular variant of papillary thyroid carcinoma: comparison of ultrasound-guided core needle biopsy and ultrasound-guided fine needle aspiration in a multicentre study

OBJECTIVE

Pre-operative diagnosis of the follicular variant of papillary thyroid carcinoma (FVPTC) by ultrasound-guided fine needle aspiration (US-FNA) remains a challenge. The goal of this study was to investigate whether ultrasound-guided core needle biopsy (US-CNB) is superior to US-FNA in refining the surgical indications for the treatment of FVPTC.

DESIGN

This retrospective study enrolled 212 patients with 218 FVPTCs who were surgically confirmed at three university hospitals from January 2008 through December 2014. All patients underwent both or either US-FNA or US-CNB. FNA and CNB results were divided into identified surgical candidates or not based on the Bethesda system. Relevant clinical information and the rate of surgical candidates were compared between US-FNA and US-CNB groups.

RESULTS

Among 218 thyroid nodules, US-FNA was performed for 200 nodules and US-CNB for 51 nodules. Thirty-three nodules underwent both US-FNA and US-CNB. The rates of surgical candidates identified by US-FNA and US-CNB were 61·5% and 86·3%, respectively (P = 0·001). The rates of surgical candidates identified by repeat US-FNA and initial US-FNA with subsequent US-CNB were 53·9% and 78·8%, respectively (P = 0·042). A precise diagnosis of FVPTC was made in 1% of the patients in the US-FNA group and in 29·4% of the patients in the US-CNB group. The predominant US findings of FVPTCs included solid tumours (89·4%), wider-than-tall shape (82·6%), no calcifications (51·3%), hypoechogenicity (46·3%) and indeterminate diagnosis on US (50·5%).

CONCLUSIONS

In patients with FVPTC, US-CNB is a superior indicator for surgery compared to US-FNA. If a FVPTC is suspected but is initially indeterminate at FNA cytology, subsequent US-CNB should be considered instead of repeat US-FNA.

Cytological Diagnosis of Follicular Variant of Papillary Thyroid Carcinoma before and after the Bethesda System for Reporting Thyroid Cytopathology

BACKGROUND

The follicular variant of papillary thyroid carcinoma (FVPTC) is the second most common subtype of papillary carcinoma after the classical variant. The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) has been introduced to standardize the practice of thyroid fine needle aspiration (FNA) reporting. We evaluated the impact of TBSRTC on the FNA interpretation of histologically proven FVPTCs.

METHOD

Cytology reports of 455 histologically proven FVPTCs were reviewed. The rate of each TBSRTC category was compared between pre- and post-TBSRTC eras.

RESULTS

The distribution of FNA diagnoses for pre-TBSRTC cases included suspicious for follicular neoplasm (SFN; n = 51, 28.7%), papillary thyroid carcinoma (PTC; n = 47, 26.4%), suspicious for malignancy (SFM; n = 32, 18%), atypia of undetermined significance (AUS; n = 23, 13%), benign (n = 18, 10.1%), and nondiagnostic (ND; n = 7, 4%). Post-TBSRTC diagnoses were: AUS (n = 68, 24.6%), PTC (n = 64, 23.1%), SFM (n = 50, 18%), SFN and benign (n = 42, 15.2%) and ND (n = 11, 4%). SFN rate decreased significantly from 28.7 to 15.2% (p = 0.001) and AUS increased from 12.9 to 24.5% (p = 0.003).

CONCLUSION

Following implementation of TBSRTC, the frequency of AUS diagnoses on FNA prior to surgical resection increased. Given that the rate of FVPTC diagnoses on thyroidectomy increased over the same period, this suggests that the use of AUS has resulted in greater surgical resection of FVPTC.

Pathologic diagnosis of papillary thyroid carcinoma: today and tomorrow

Papillary thyroid carcinoma is the most common malignancy of the thyroid. It is a well-differentiated tumor and the majority behaves in an indolent fashion. The pathologic diagnosis of papillary carcinoma in both cytology and histologic specimens is based upon demonstration of typical nuclear morphology. Using these morphologic criteria, most papillary cancers can be diagnosed with ease, except cases in which there is a paucity of diagnostic nuclear features. Despite advances in the treatment of thyroid cancer, disease recurrences and metastasis can be observed in 20% of cases. Recently, many advances have been made in the pathogenesis of papillary thyroid carcinoma. The notable genetic events include Ret/PTC rearrangements, Ras and BRAF gene mutations. The identification of these has also led to their use in diagnosis and predicting prognosis of papillary thyroid carcinoma. In addition, these involved genes may also serve as targets for cancer chemotherapy in patients where standard thyroid cancer treatment is not effective.

Better understanding in the differentiation of thyroid follicular adenoma, follicular carcinoma, and follicular variant of papillary carcinoma: a retrospective study

Background. To evaluate the role of ultrasonography (US), US-guided fine-needle aspiration (USFNA) and intraoperative frozen section (FS) in follicular neoplasm. Methods. US features, USFNA cytology, and FS results were compared based on the pathology results of patients with follicular adenoma (FA), follicular carcinoma (FC), and follicular variant of papillary thyroid carcinoma (FVPTC). Results. FC and FVPTC showed significantly higher rates of suspicious US features (P < 0.05) and positive findings on either US or cytology, 80.0% and 90.7%, compared to FA, 64.5% (P = 0.001). Intraoperative FS showed higher malignant rates in FVPTC and FC (81.8% and 75.0%, resp.), compared to FA (3.8%, P < 0.001). Conclusion. Suspicious US features were more significantly seen in FC and FVPTC compared to FA. Intraoperative FS is useful in the differential diagnosis of these lesions and supplements cytology results of USFNA.

Secondary or second primary malignancy in the thyroid? metastatic tumors suggested clinically: a differential diagnostic task

OBJECTIVE

To describe the algorithms employed to explore the suggestion or consideration of metastatic malignancy in the thyroid.

STUDY DESIGN

Thirty-seven cases with a history of malignancy (n = 21) and/or uncommon fine-needle aspiration biopsy (FNAB) findings (n = 37) were reviewed and reclassified according to The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC).

RESULTS

The group was heterogeneous in terms of the final histopathology results: the suggested metastasis was confirmed in only half of the cases (11/21; 52.4%). Primary thyroid malignancies were mostly nondifferentiated, medullary, or rare. However, 3 papillary carcinomas (the less common variants) were also found. Finally, 5 out of 37 cases were surprisingly benign upon histopathological investigation (uncommon repair and fibrotizing Hashimoto thyroiditis).

CONCLUSIONS

The metastatic nature of thyroid gland nodule(s) must be considered in cases of generalization of malignancy and/or uncommon FNAB findings. We must be as open-minded as possible from the outset. Additional techniques are helpful if available - cytoblock and immunocytochemistry can contribute substantially. Morphological comparisons with the previous malignancy are recommended whenever possible. To avoid overtreatment, cases without precise typing should not be classified as TBSRTC diagnostic category VI - malignant, but should remain in TBSRTC diagnostic category V - suspicious for malignancy. Repeated FNAB to enable additional techniques may be suggested.

Molecular genotyping of follicular variant of papillary thyroid carcinoma correlates with diagnostic category of fine-needle aspiration cytology: values of RAS mutation testing

BACKGROUND

The follicular variant of papillary thyroid carcinoma (FVPTC) presents distinct histologic subtypes and molecular genotyping. The preoperative diagnosis of FVPTC through fine-needle aspiration cytology (FNAC) is challenging.

METHODS

We reviewed 59 archival thyroid FNAC specimens of surgically confirmed FVPTC according to histologic subtype: encapsulated FVPTC (n = 30) and infiltrative FVPTC (n = 29). Galectin-3 immunostaining and molecular analyses for BRAF and three RAS genes (NRAS, HRAS, and KRAS) were performed.

RESULTS

FNAC diagnoses of FVPTC included benign (5%), atypia of undetermined significance (19%), follicular neoplasm/suspicious for follicular neoplasm (14%), suspicious for PTC (29%), and PTC (34%). Galectin-3 immunostaining was positive in 50% of FNAC specimens. A BRAF mutation was found only in 14 (24%) tumors with the FNAC diagnosis of PTC or suspicious for PTC: 13 cases with the usual c.1799T>A (p.V600E) mutation and 1 case with a 3 base-pair deletion (c.1799_1801delTGA), resulting in a deletion of lysine at codon 601 and a deletion c.1799_1801delTGA that results in a valine-to-glutamate substitution at codon 600 (p.V600_K601>E) while preserving the reading frame. A BRAF K601E mutation was not found. RAS mutations were observed in 18 (33%) tumors (NRAS, 22%; HRAS, 6%; KRAS, 6%). Mutations of the three RAS genes were detected in codon 61 but not in codons 12 and 13. There was a decreasing trend of RAS mutation rates associated with an increasing risk of malignancy in the FNAC diagnostic categories. The triage efficacy of FNAC to make a recommendation for surgery was 73% for encapsulated tumors and 79% for infiltrative tumors. Addition of galectin-3 or the BRAF test to FNAC showed no significant improvement in the triage efficacy. However, RAS mutations significantly improved the triage efficacy of FNAC. There was no significant difference in the triage efficacy of FNAC, galectin-3 expression, and the prevalence of somatic mutations between encapsulated and infiltrative tumors.

CONCLUSION

Thyroid FNAC has a low sensitivity for the detection of FVPTC regardless of histologic subtype. Encapsulated FVPTC and infiltrative FVPTC have similar molecular profiles and rates of galectin-3 expression. RAS mutational analysis is more useful than BRAF testing to improve the triage efficacy of FNAC for FVPTC.

The new molecular markers DDIT3, STT3A, ARG2 and FAM129A are not useful in diagnosing thyroid follicular tumors

Preoperative characterization of thyroid follicular lesions is challenging. Fine-needle aspiration specimens cannot differentiate follicular carcinomas from benign follicular neoplasias. Recently, promising markers have been detected using modern molecular techniques. We conducted a retrospective study to confirm the usefulness of immunohistochemical staining for the protein markers, DDIT3, STT3A (ITM1), ARG2 and FAM129A (C1orf24) in separating benign and malignant thyroid follicular lesions. Formalin-fixed, paraffin-embedded thyroid tissue from 30 in-house cases (15 follicular carcinomas and 15 follicular adenomas), as well as 8 follicular carcinomas and 21 follicular adenomas on tissue microarray slides were stained immunohistochemically for DDIT3, STT3A, ARG2 and FAM129A expression. Control tissue consisted of thyroid parenchyma adjacent to the tumors and 11 separate cases of normal thyroid parenchyma. All in-house cases of follicular adenomas, follicular carcinomas and adjacent normal thyroid tissue showed positive immunostaining with anti-DDIT3 and anti-STT3A. Anti-ARG2 and anti-FAM129A polyclonal antibodies showed positive staining in 20 and 60% of in-house follicular adenomas, and 40 and 87% of in-house follicular carcinomas, respectively. Monoclonal anti-FAM129A demonstrated positive staining in 13 and 33% of in-house follicular adenomas and follicular carcinomas, respectively. Polyclonal anti-DDIT3, -STT3A and -FAM129A antibodies showed positive staining in all tissue microarray slides of follicular carcinoma and in 76, 85 and 81% of the follicular adenomas, respectively. Monoclonal anti-STT3A stained 81% of the follicular adenoma cores. Anti-ARG2 stained positive in 13% of follicular carcinomas and 10% of follicular adenomas on the tissue microarray slides. In conclusion, DDIT3, STT3A, ARG2 and FAM129A immunohistochemistry does not appear to be useful in the diagnosis of thyroid follicular neoplasias, as they do not reliably distinguish follicular thyroid carcinoma from follicular thyroid adenoma.

A cell pattern approach to interpretation of fine needle aspiration cytology of thyroid lesions: A cyto-histomorphological study

Aim:

Our study aimed at a cell pattern approach to interpret thyroid cytology and to demonstrate diagnostic accuracy of fine needle aspiration cytology (FNAC) with an emphasis on diagnostic pitfalls.

Materials and Methods:

A total number of 218 goitre cases, from the year 2000 to 2004, were reviewed retrospectively from the cytology files, without considering the previous cytological diagnosis. Four cases with inadequate aspirate were excluded. The predominant cell pattern, such as macro/normofollicular, microfollicular, papillary, syncytial, dispersed and cystic pattern, was noted in each case. The final diagnosis was arrived by observing the cellular details and background elements. Cytological diagnosis was correlated with histopathology in 75 cases. The sensitivity and specificity were computed.

Results:

Normo/macrofollicular pattern was seen in 71.96% of nodular goitre and 6.9% of follicular neoplasms. Around 86.2% of follicular neoplasms and 17.6% of papillary carcinoma had microfollicular pattern. The papillary pattern was seen in 47% of papillary carcinoma. Syncytial pattern was noticed in 72.3% of chronic lymphocytic thyroiditis and 29.4% of papillary carcinoma. Cytological diagnosis was concordant with histopathological diagnosis in 65 cases. Overall sensitivity and specificity of FNAC in diagnosing neoplastic lesions of thyroid were 83.33 and 95.55%, respectively.

Conclusion:

FNAC is more sensitive and specific in triaging neoplastic from non-neoplastic thyroid lesions. Identification of the predominant cell pattern would be complementary to analysis of cell morphology and background details in cytological diagnosis of thyroid lesions. This approach helps to diagnose follicular neoplasm and follicular variant of papillary thyroid carcinoma.

Classical and follicular variant papillary thyroid carcinoma: comparison of clinical, ultrasonographical, cytological, and histopathological features in 444 patients

Follicular variant papillary thyroid carcinoma (FVPTC) is the most common variant of papillary thyroid carcinoma (PTC) after classical PTC (CPTC). In this study, we aimed to compare functional status, ultrasonographical features, cytological results, and histopathological characteristics of patients with CPTC and FVPTC. Preoperative thyroid functions, thyroid autoantibodies, ultrasonographical features, cytology, and histopathology results of 354 (79.9%) CPTC and 90 (20.3%) FVPTC patients were reviewed retrospectively. Sex distribution, mean age, thyroid autoantibody positivity, and thyroid dysfunctions were similar in two groups. Among 320 patients with preoperative ultrasonography (US) findings, a hypoechoic halo was observed more frequently (p=0.003), and marginal irregularity was observed less commonly (p=0.024) in FVPTC lesions. In CPTC, rate of malignant cytology (p=0.001), and in FVPTC, rate of suspicious cytology (p<0.001) were significantly higher. Histopathologically, mean tumor diameter was markedly higher in FVPTC compared to CPTC (16.89 ± 13.86 vs 10.64 ± 9.70 mm, p<0.001), while capsular invasion and extrathyroidal spread were significantly lower in patients with FVPTC (p=0.018 and p=0.039, respectively). FVPTC tend to have more benign features in US and less malignant results in cytology. Higher tumor size in FVPTC might be explained by the recognition of clinical importance of these lesions after reaching particular sizes due to benign US features.

Fine-needle aspiration of follicular patterned lesions of the thyroid: Diagnosis, management, and follow-up according to National Cancer Institute (NCI) recommendations

The National Cancer Institute (NCI) State of the Science Conference on thyroid fine-needle aspiration (FNA) proposed that follicular patterned lesions can be divided into two diagnostic categories; follicular lesion of undetermined significance/Atypia of undetermined significance (FLUS/AUS) and suspicious for follicular neoplasm/follicular neoplasm (SFON/FON). The former group can benefit from repeat FNA (RFNA) to achieve a more definitive diagnosis and the latter should undergo surgical excision for histologic characterization (adenoma vs. carcinoma). In this study, we report the combined experience from our institutions with thyroid FNA cases that can be placed into NCI-designated thyroid FNA diagnostic categories for follicular patterned lesions.The case cohort comprised of 857 cases in 645 females and 212 males; 509 cases could be classified as FLUS/AUS and 348 as SFON/FON. Histologic follow-up was available in 273/509 (54%) cases diagnosed as FLUS/AUS and 251/348 (72%) cases diagnosed as SFON/FON.RFNA was performed in 203/509 (40%) patients classified as FLUS/AUS. RFNA diagnoses were: benign (125 cases), FLUS (46 cases), SFON/FON (20 cases), suspicious for papillary carcinoma (7 cases), papillary carcinoma (3 cases) and non-diagnostic (2 cases). The malignancy rate on surgical excision in the FLUS/AUS group was 27 and 15% with and without RFNA, respectively; and 25% in cases diagnosed as SFON/FON.RFNA is effective in managing thyroid nodules diagnosed as FLUS/AUS since the malignancy rates are different in cases with or without RFNA (27% vs. 15%). The malignancy rate (25%) in cases diagnosed as SFON/FON is similar to reported by other authors.

Differential expression of galectin-3, CK19, HBME1, and Ret oncoprotein in the diagnosis of thyroid neoplasms by fine needle aspiration biopsy

Background:

Fine needle aspiration biopsy (FNAB) is a common and excellent procedure for the evaluation of thyroid lesions that require surgical resection. At times, the FNAB diagnosis can be difficult, particularly of follicular-patterned lesions. Previous studies have shown that some immunohistochemical (IHC) markers may be helpful in establishing more accurate diagnosis. In this study, our goal was to evaluate four of the recently investigated markers in differentiating benign from malignant thyroid nodules on FNABs.

Materials and Methods:

We performed IHC staining of galectin-3, Ret oncoprotein (Ret), HBME-1, and cytokeratin 19 (CK19), on cell block sections of thyroid FNAB cases that had corresponding surgical resections. They included 44 benign lesions (37 hyperplastic or cellular nodules, HN; and 7 follicular adenomas, FA) and 27 malignant tumors (6 follicular carcinoma, FC; 19 classic papillary carcinoma, PTC; and 2 follicular variant of papillary carcinoma, FVPC). The stains were done according to the standard avidin–biotin–peroxidase method.

Results:

Statistical analysis showed that immunoexpression was significantly higher in the malignant group for all four markers. The sensitivity for positive expression for all benign lesions versus malignant tumors was as follows: 10/44 (22.7%) versus 25/27 (92.6%) for galectin-3; 14/44 (31.8%) versus 23/27 (85%) for Ret; 12/44 (27.3%) versus 24/27 (88.8%) for HBME-1; and 13/44 (29.5%) versus 23/27 (85%) for CK19. The sensitivity and specificity was highest for galectin-3 (92.6% and 77.3%, respectively) followed by HMBE-1 (88.9% and 72.7%, respectively). When combining the markers' expressions, the panel of galectin-3 + HBME-1 showed the highest sensitivity and specificity (90.7% and 75%, respectively), but this was, however, lower than galectin-3 alone (92.3% and 77.3%, respectively).

Conclusion:

We conclude that galectin-3 is the best single marker in differentiating benign from malignant thyroid lesions with the highest sensitivity and specificity. The galectin-3 + HBME-1 was the best combination for distinguishing benign from malignant lesions. Because they were the best two independent and combined markers, we recommend the use of the galectin-3 + HBME-1 panel to enhance the diagnostic accuracy of follicular-patterned thyroid lesions on FNABs.

Diagnostic terminology and morphologic criteria for cytologic diagnosis of thyroid lesions: a synopsis of the National Cancer Institute Thyroid Fine-Needle Aspiration State of the Science Conference

The National Cancer Institute (NCI) sponsored the NCI Thyroid Fine-needle Aspiration (FNA) State of the Science Conference on October 22-23, 2007 in Bethesda, MD. The two-day meeting was accompanied by a permanent informational website and several on-line discussion periods between May 1 and December 15, 2007 (http://thyroidfna.cancer.gov). This document summarizes matters regarding diagnostic terminology/classification scheme for thyroid FNA interpretation and cytomorphologic criteria for the diagnosis of various benign and malignant thyroid lesions. (http://thyroidfna.cancer.gov/pages/info/agenda/).

Follicular neoplasm of the thyroid--vanishing cytologic diagnosis?

The significance of making a diagnosis of follicular neoplasm on fine needle aspiration (FNA) biopsy remains a controversial issue, considering that the diagnosis of follicular carcinoma is based on histological criteria and the significantly decreasing incidence of follicular carcinoma in the general population. On FNA the main differential diagnoses of follicular neoplasm includes follicular variant of papillary carcinoma (FVPC), follicular adenoma, follicular carcinoma and benign solitary nodule occurring in a goiter. Several studies have looked at immunohistochemical and molecular markers to distinguish benign from malignant lesions but none of them have proved to be infallible. Although, FVPC is a distinct entity from the follicular neoplasm group, it is not always possible to separate it from the other follicular lesions because of overlapping cytologic features and often-sporadic presence of nuclear features, follicular variant of papillary carcinoma remains the main pitfall in a diagnosis of follicular neoplasm. Since a significant number of cases that are malignant on follow-up are usually FVPC, consequently, follicular neoplasm is an essential diagnostic consideration on FNA. In addition, follicular carcinoma, despite a decreasing incidence continues to be a real entity. Therefore, it is essential that follicular neoplasm continue to be part of our diagnostic repertoire.

Characterization of follicular thyroid nodules at fine needle aspiration biopsy using double phase thallium-201 imaging: comparison of visual and semiquantitative analyses

OBJECTIVE

To compare visual and semiquantitative indices of double phase thallium-201 thyroid scintigraphy (DTS) for differentiation of malignant nodules by indeterminate fine needle aspiration biopsy (FNAB) results.

DESIGN

DTS (early; 15 minutes; delayed, 2 hour) were performed after injection of 37MBq of thallium-201 in 60 patients with indeterminate FNAB.

MAIN OUTCOME

With grade 4 and 5, sensitivity and specificity were 51.4% and 78.3%, respectively. With early lesion to nonlesion ratio (L/N) 1.49, sensitivity and specificity were 97.3% and 39.1%, respectively. With delayed L/N 1.89, sensitivity and specificity were 70.3% and 78.3%, respectively. With wash-out rate (WR) 18.93%, sensitivity and specificity were 89.2% and 82.6%. Early L/N was superior to delayed L/N and WR for the detection of malignant thyroid nodules.

CONCLUSION

Visual assessment had a limited value for differentiation of follicular nodules. The optimal semiquantitative indices were 1.49 for early L/N and 1.89 for delayed L/N. Also, optimal WR was 18.93%. The early L/N was superior to delayed L/N and WR for the detection of malignant thyroid nodular lesions. However, visual assessment and early L/N of DTS showed similar results. Visual analysis and semiquantitative indices of DTS could not differentiate follicular carcinoma and follicular variant of papillary thyroid cancer.

Clinical Presentations and Outcomes of Surgical Treatment of Follicular Variant of the Papillary Thyroid Carcinomas

BACKGROUND

The follicular variant of papillary thyroid carcinoma (FVPTC) presents with biological and morphological features similar to papillary thyroid carcinoma. Pre-operative diagnosis of FVPTC and its clinical course is important in identifying appropriate surgical procedures.

METHODS

This study enrolled 85 patients, 68 females (mean age 41.4+/-13.7 years) and 17 males (mean age 50.1+/-12.3 years) with papillary thyroid carcinomas diagnosed as FVPTC. From the patient database at Chang Gung Medical Center (CGMC), 170 pure papillary thyroid carcinoma cases and 85 with minimally invasive follicular thyroid carcinomas of gender- and age-matched patients were randomly selected as control groups. All patients were categorized into high- and low-risk groups according to AMES criteria.

RESULTS

Of the three groups, 7.1% (follicular), 11.8% (FVPTC) and 34.1% (pure papillary thyroid carcinoma) of patients presented with lymph node or soft tissue invasion (P=0.0001). Additionally, 29.4, 11.8 and 2.4% of patients with follicular carcinoma, FVPTC and pure papillary thyroid carcinoma, respectively, presented with distant metastases at the time of diagnosis. Of the 85 FVPTC cases, 75 underwent pre-operative fine needle aspiration cytology (FNAC) examination at CGMC. Only 11 cases were diagnosed pre-operatively with papillary thyroid carcinomas. Kaplan-Meier survival curves for these three groups demonstrated that follicular thyroid carcinoma had a prognosis worse than both papillary thyroid carcinomas.

CONCLUSIONS

Most FVPTC cases were diagnosed as follicular neoplasm via pre-operative FNAC. In this study, FVPTC patients had a high ratio of distant metastases, few lymph node metastases and soft tissue invasion. Aggressive treatment was indicated for the high-risk FVPTC patients.

Diagnostic value of galectin-3 as a marker for malignancy in follicular patterned thyroid lesions

BACKGROUND

The determination of malignancy in follicular patterned thyroid lesions is based on postoperative histologic findings. Therefore, affected patients are referred for surgery, although only 20% will have a final diagnosis of malignancy. The aim of this study was to investigate the potential of galectin-3 as a marker of malignancy in these lesions.

METHODS

Fifty-four tissue specimens of follicular patterned thyroid lesions were immunohistochemically stained for galectin-3. Area and intensity scores were recorded.

RESULTS

Significant differences were found between the benign and malignant lesions. The sensitivity, specificity, positive predictive values, and negative predictive values of galectin-3 staining were 82%, 68%, 75%, and 77%, respectively (p=.0002). Significant differences were also found between the subgroups of benign and malignant lesions (p < or =.05).

CONCLUSIONS

Galectin-3 staining is highly sensitive for malignancy in follicular patterned thyroid lesions. Diagnostic problems may arise in the presence of Hurthle cell proliferation or minimally invasive follicular carcinoma.

Role of Fine-needle Aspiration Biopsy and Frozen Section in the Management of Papillary Thyroid Carcinoma Subtypes

Since fine-needle aspiration biopsy (FNAB) was introduced, the value of frozen section (FS) has been questioned. This study compares FNAB and FS sensitivities among the usual form of papillary thyroid cancer (uPTC) and variants of PTC such as tall cell (tcPTC), follicular (fPTC), and Hurthle cell (HcPTC). A total of 257 patients who underwent preoperative FNAB, intraoperative FS, and thyroidectomy for PTC were, randomly selected from a database of a university teaching hospital in Toronto. There were 218 females (84.8%) and 39 males (15.2%), from 19 to 89 years of age (mean of 44 years), having uPTC (n = 212), fPTC (n = 24), HcPTC (n = 14), and tcPTC (n = 7). Data were analyzed using chi2 test. Sensitivities were calculated by division of true positives and by the sum of true positives and false negatives. True positives had to reflect a conclusive diagnosis of cancer. The FNAB sensitivities were uPTC (39.2%), fPTC (25%), HcPTC (42.9%), tcPTC (85.7%), similar to FS sensitivities (p = 0.497) for uPTC (44.3%), fPTC (16.7%), HcPTC (42.9%), and tcPTC (71.4%). Use of FS following FNAB increased sensitivities for uPTC to 56.1%, fPTC to 29.2%, and tcPTC to 100%. In addition, FS did not increase FNAB sensitivity in HcPTC. Combination FNAB plus FS failed in 43.9% of uPTC, 70.8% of fPTC, and 57.1% of HcPTC. We concluded that FNAB and FS sensitivity vary with PTC subtype and are still necessary for selection and treatment. The recognition of morphologic subtypes of PTC from the FNAB could optimize the selection of patients for intraoperative FS, enhance the preoperative assessment of prognosis, facilitate the surgical planning, and simplify the preparation of postoperative adjuvant therapy.

Follicular variant of papillary thyroid carcinoma - a cytological study

The cytological diagnosis of classical papillary carcinoma is easily established based on the characteristic architectural and nuclear features. However, the follicular variant of papillary thyroid carcinoma(FVPTC) poses a diagnostic challenge. In this study we analysed the cytological features of 14 histopathologically proven cases of FVPTC. We inferred that a combination of architectural features such as follicles and syncytial clusters and nuclear features, viz grooves, pseudoinclusions and enlarged nuclei with fine chromatin, were helpful in establishing the diagnosis. It is hence suggested that based on the combination of the aforesaid features a diagnosis of FVPTC be offered whenever it is possible. This helps in patient management, obviating the need for a second surgical intervention.

Absence of histological malignancy in a patient cohort with follicular lesions on fine-needle aspiration

Follicular lesions account for 4-6% of all thyroid fine-needle aspiration (FNA) cytologies. To date, no cytological criteria exist to distinguish follicular adenoma from carcinoma. For this purpose, histological evaluation after surgical exeresis is required. From 1993 to 2000 we performed 1,238 US-assisted FNA biopsies in patients admitted to our unit for uni- or multi-nodular goiters. In the latter goiters, FNA was performed in the dominant nodule. Cytological examination revealed a follicular lesion in 71 patients (5.7%). All patients came from regions of Northern Italy with moderate iodine deficiency. In 48%, the lesion presented as a solitary nodule, while in the other 52% it occurred in the context of a multinodular goiter. Surgical exeresis of the neoplasm was recommended in all cases. Sixty-three patients (89%) underwent surgery (Group 1) while the other 8 patients (11%) opted for follow-up (Group 2). In Group 2, the mean nodule volume (3.2 +/- 0.5 ml) at baseline was slightly smaller (p = 0.08) than that found in Group 1 (5.4 +/- 0.7 ml). In Group 1, histological examination after surgery showed a follicular adenoma in 52 patients (83%) and a colloid goiter in the others (17%). No malignancy was detected. Group 2 underwent a median follow-up of 46 months (range 24-96 months) on L-thyroxine suppressive regimen (dose range 75-125 pg/day), with TSH levels ranging from 0.1 to 0.3 mlU/l. Throughout the follow-up, no patient developed clinical or ultrasonographic features that could be considered worrisome for malignancy; thus, no further biopsy was performed. However, an overall slight increase (median +5.2%) in nodular volume in respect to baseline was observed. Although institutional and cytological bias cannot be ruled out, our data do not confirm the reported incidence of malignancy in histological specimens of follicular lesions diagnosed on FNA cytology, and prompt us to suggest a less aggressive first-step approach (i.e. careful clinical and instrumental evaluation, and suppressive L-T4 therapy) for these lesions, unless anamnestic reports or clinical and ultrasonographic features of the nodules suggest malignancy.

Follicular-patterned lesions of the thyroid: the bane of the pathologist

This review focuses on follicular-patterned lesions of the thyroid gland and their differential diagnosis. Included are a discussion of the features differentiating follicular adenoma from adenomatous or hyperplastic nodule and follicular adenoma from follicular carcinoma and the follicular variant of papillary thyroid carcinoma. The cytologic and histologic characteristics are described, and criteria for diagnosing the major follicular lesions are reviewed.

Follicular variant of papillary carcinoma: cytologic findings on FNAB samples-experience with 16 cases

Between January 1, 1992 and December 31, 1997, a cytopathological diagnosis of follicular variant of papillary thyroid carcinoma (FVPC) was made on a series of 16 out of 18 patients with palpable nodules who underwent fine-needle aspiration biopsy (FNAB) in our Department. The results of aspiration biopsy were followed by histopathological examination of the surgically excised tissues. There were three false-negative aspirations (16.6%), of which two were probably bound to fine-needle sampling and one due to a mixture of benign and malignant cells which had originally gone unrecognized. The accuracy of the cytopathologic diagnosis in this variant was 88.8%. An analysis of the diagnostic cytopathological criteria was performed, which demonstrated the importance of both architectural features (monolayered and branching sheets, microacinar structures, and their combinations) and nuclear features (presence of nuclear grooves). Background -bound features were mainly represented by dense, nonfilamentous colloid. The cytopathologic findings in FVPC were compared to those found in a series of 10 usual papillary carcinomas (UPC) and 10 follicular neoplasms (FN). These latter had originally been diagnosed by FNAB and were subsequently classified histologically as follicular adenoma (n = 6), follicular carcinoma (n = 3), or adenomatoid colloid nodule (n = 1). Statistical evaluation was performed on the cytopathological findings in the three classes of lesions (FVPC, UPC, and FN) as to their presence and relative frequency or absence by using a nonparametric one-way ANOVA (Kruskall-Wallis) and, where necessary, a Mann-Whitney U test. Papillary cellular fragments and multinucleated giant cells (P < 0.005), nonfilamentous dense colloid, squamoid cells, and syncytia were significantly more represented in UPC than in FVPC (P < 0.05), while histiocytes were significantly more frequent in FVPC (P < 0.005). Other nuclear and/or background features were significant only in the distinction between papillary carcinomas as a group and FN. The cytological differential diagnosis of the FVPC is briefly discussed with relevance to the possible pitfalls caused by its peculiar cyto- and histomorphology.

Thyroid cytology and the risk of malignancy in thyroid nodules: importance of nuclear atypia in indeterminate specimens

Fine needle aspiration (FNA) cytology is the best test for malignancy in thyroid nodules. However, cytologic interpretation of FNA specimens is often difficult, especially in the presence of indeterminate microfollicular cytologic patterns, which are thought to suggest follicular neoplasm (adenoma or carcinoma). To assess the risk of malignancy associated with specific cytologic patterns, we correlated preoperative FNA cytologic patterns (n = 484 reports including repeat aspirations) with final histological diagnoses for 368 surgical thyroid specimens obtained during the period 1994-1998. The overall prevalence of malignancy in the surgical specimens was 31% (113 cancers, including 96 papillary and 9 follicular carcinomas). For nodules with benign FNA cytologic diagnoses of nodular goiter and chronic thyroiditis there was a low risk of malignancy (6/99, or 6.1%). Nodules with indeterminate cytologic patterns in the absence of nuclear atypia (i.e., microfollicles without nuclear atypia) had a similarly low malignancy risk (3/46, or 6.5%). In contrast, 31/52 nodules with cytologic nuclear atypia consistent with follicular neoplasm were malignant (60%), including specimens with or without microfollicular cytology. Nodules with frankly malignant cytologic patterns were almost invariably cancer (54/55), and cytologic diagnoses of papillary carcinoma were confirmed at surgery in all 49 cases. These results indicate that indeterminate microfollicular cytologic patterns in the absence of nuclear atypia are associated with a low risk of malignancy, at least in this series. This finding suggests that many nodules with such microfollicular cytology might be managed conservatively with observation. In contrast, cytologic nuclear atypia consistent with a follicular neoplasm confers a high risk of cancer. In addition, frankly malignant cytologic diagnoses, especially papillary carcinoma, are highly reliable, and thus may be used as a guide for planning surgery appropriate for thyroid cancer.

Thyroid nodules with FNA cytology suspicious for follicular variant of papillary thyroid carcinoma: follow-up and management

Thyroid nodules diagnosed as follicular neoplasm on fine-needle aspiration biopsy (FNAB) may represent hyperplastic/adenomatous nodules, follicular adenoma or carcinoma, and follicular variants of papillary thyroid carcinoma (FVPTC) on histologic follow-up. In our laboratory, we attempted to identify a subset of cases which showed cellular specimens with focal features (nuclear chromatin clearing, membrane thickening, and rare grooves) suspicious for the follicular variant of papillary thyroid carcinoma. These cases are reported as follicular-derived neoplasms with nuclear features suspicious for FVPTC to distinguish them from those diagnosed as follicular neoplasm. This study documents our experience with 52 cases so diagnosed and followed prospectively with histologic follow-up. A neoplastic nodule was confirmed in 45/52 cases (86%), of which 40 were malignant (77%). FVPTC was identified in 35/52 cases (67%). Four cases were usual papillary carcinoma, 3 were follicular adenoma, 2 were Hürthle-cell adenoma, and 1 was insular carcinoma. In 7 cases, the subsequent histologic findings were nonneoplastic (5 hyperplastic nodules and 2 colloid nodules). Our prospective study shows that in cellular smears from thyroid nodules, a careful search for the nuclear features of papillary carcinoma should be performed, and it is appropriate to diagnose cases as suspicious for FVPTC if the nuclear features of papillary carcinoma are focal. The surgical management of this group may include an intraoperative confirmation of cytologic diagnosis by scrape preparation and/or frozen section in order to avoid a second surgical intervention for completion thyroidectomy.

Follicular variant of papillary carcinoma: the diagnostic limitations of preoperative fine-needle aspiration and intraoperative frozen section evaluation

OBJECTIVE

Fine-needle aspiration (FNA) and frozen section (FS) have been widely reported in the literature as having high sensitivity in the diagnosis of papillary carcinoma. With the increased recognition of the follicular variant of papillary thyroid carcinoma (FVPTC), several reports have pointed out the difficulty in diagnosing this variant of papillary carcinoma owing to its overlapping cytomorphological features with benign and malignant follicular lesions. We undertook this study to determine the sensitivity of FNA and FS in the diagnosis of FVPTC.

METHODS

Retrospective review of patients who underwent thyroidectomy from June 1994 to June 1999. Of the 63 patients found with a final pathological diagnosis of papillary thyroid carcinoma, only 47 had an adequate FNA and FS and were included in the study. These patients were divided into two groups, the usual type (n = 23) and the follicular variant (n = 24) of papillary carcinoma. Sensitivities of FNA and FS for these two groups of papillary carcinoma were then determined.

RESULTS

The sensitivity of the FNA was 25% and of the FS was 29% for the follicular variant of papillary thyroid carcinoma. This is in contrast to the sensitivity of FNA and FS for the usual papillary carcinoma, which were 74% and 87%, respectively.

CONCLUSION

FNA and FS have low sensitivity in the diagnosis of the FVPTC. High degree of suspicion may increase the accuracy in the diagnosis of this variant of papillary carcinoma before or during surgery. However, the thyroid surgeon needs to realize that, like follicular carcinoma, FVPTC is often diagnosed only on final pathological examination.