Cytological Diagnoses Associated with Noninvasive Follicular Thyroid Neoplasms with Papillary-Like Nuclear Features According to the Bethesda System for Reporting Thyroid Cytopathology: A Systematic Review and Meta-Analysis

NIFTP-adjusted risk estimation of Bethesda thyroid cytology categories should consider the indication for FNA according to TIRADS

BACKGROUND

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was firstly described in 2016. Since NIFTP is thought a non-malignant tumor, the Bethesda system for thyroid cytology proposes two estimations of risk of malignancy of the diagnostic categories, one considering NIFTP as cancer and another one considering it as a benign neoplasm. The present study aimed to review NIFTPs in a single center, re-assess them across categories of three Thyroid Imaging Reporting and Data Systems (TIRADSs), and define the indication for biopsy according to the category-specific size cut-offs.

METHODS

The study period was from 2017 to 2023. The institutional database was searched for histologically proven NIFTPs with preoperative ultrasound images. NIFTPs were re-assessed according to the American College of Radiology (ACR), European (EU), and Korean (K) TIRADSs. The indication for biopsy was defined according to TIRADS category-specific size threshold.

RESULTS

Twenty NIFTPs from 19 patients were included. The median size of the NIFTPs was 23 mm. According to ultrasound, 80-85% of NIFTPs were at low-intermediate risk and 5-15% at high risk without significant difference among the tree TIRADSs (p = 0.91). The indication for FNA, according to three TIRADSs, was found in 52-58% of cases with no significant difference among systems (p = 0.96).

CONCLUSION

NIFTPs have heterogeneous presentation according to TIRADSs with very low indication rate for FNA.

An investigation into noninvasive follicular thyroid neoplasms with papillary-like nuclear features: does the initial proposal on noninvasive follicular thyroid neoplasms with papillary-like nuclear features behavior hold true?

Current management of patients with noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP) is lobectomy with close clinical follow-up. Because this entity is still young, we present our 5-year institutional experience with NIFTP since that time. Cases of NIFTP diagnosed from 2017 to 2022 were identified. Data points including patient demographics, radiology, cytologic and pathologic diagnoses, molecular profiles, and clinical follow-up were documented. A literature review of NIFTP case series was performed. A total of 379 cases were included (mean age: 52 years, female:male ratio 3.3:1). Ultrasound findings were available for 260 patients, and 247 underwent fine-needle aspiration (FNA). The FNA diagnoses per the Bethesda System for Reporting Thyroid Cytology were nondiagnostic (n = 2), benign (n = 16), atypia of undetermined significance/follicular lesion of undetermined significance (n = 119), follicular neoplasm/suspicious for follicular neoplasm (n = 68), suspicious for malignancy (n = 31), and malignant (n = 11). Molecular testing was performed in 179 cases. Lobectomy was performed for 183, total thyroidectomy for 192, and nodulectomy for 4 cases. The average size of NIFTP was 2.3 cm, and 232 cases had additional nodules (including benign and malignant neoplasms). Multifocal NIFTP occurred in 32 patients. Lymph nodes were evaluated in 196 cases with metastatic carcinoma in 29 cases (all with concurrent diagnoses of carcinoma). Most patients were alive at follow-up, 100 were lost to follow-up, and three died from other causes. Literature review revealed 2870 NIFTP cases with similar patient demographics and pathologic findings. We confirm that NIFTP is a low-risk neoplasm with indolent clinical behavior, which can be managed conservatively.

Identification of NIFTP-Specific mRNA Markers for Reliable Molecular Diagnosis of Thyroid Tumors

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a low-risk thyroid tumor with a favorable prognosis. Nonetheless, differentiating NIFTP from other thyroid tumors remains challenging, necessitating reliable diagnostic markers. This study is aimed at discovering NIFTP-specific mRNA markers through RNA sequencing analysis of thyroid tumor tissues. We performed mRNA expression profiling for 74 fresh frozen thyroid tissue samples, including NIFTP and benign and malignant follicular-cell-derived tumors. NIFTP/malignant tumors showed 255 downregulated genes and 737 upregulated genes compared to benign tumors. Venn diagram analysis revealed 19 significantly upregulated and 7 downregulated mRNAs in NIFTP. Akaike information criterion analysis allowed us to select OCLN, ZNF423, LYG1, and AQP5 mRNA markers. We subsequently developed a predictive model based on logistic regression analysis using these four mRNAs, which we validated in independent samples (n = 90) using a qRT-PCR assay. This model demonstrated high accuracy in predicting NIFTP in discovery dataset (AUC (area under the receiver operating characteristic) = 0.960) and the validation dataset (AUC = 0.757). Our results suggest that OCLN, ZNF423, LYG1, and AQP5 mRNA markers might serve as reliable molecular markers for identifying NIFTP among other thyroid tumors, ultimately aiding in accurate diagnosis and management of NIFTP patients.

Ultrasound features and risk stratification system in NIFT-P and other follicular-patterned thyroid tumors

OBJECTIVE

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFT-P) is an encapsulated follicular variant of papillary thyroid carcinoma (PTC) with nonaggressive clinical behavior. However, since its diagnosis is exclusively possible after surgery, it represents a clinical challenge. Neck ultrasound (US) shows good sensitivity and specificity in suggesting malignancy in thyroid nodules. However, little information is available about its ability in identifying NIFT-P.

DESIGN

The aim of this study was to evaluate the US features of NIFT-P, comparing them with other follicular-patterned thyroid tumors, and to test the ability of the main US risk stratification system (RSS) in identifying NIFT-P.

METHODS

We retrospectively evaluated 403 consecutive patients submitted to thyroid surgery, with positive histology for at least 1 nodule being NIFT-P, follicular variant of PTC (FV-PTC), follicular thyroid carcinoma (FTC), or follicular adenoma (FA).

RESULTS

The US features of NIFT-P (n = 116), FV-PTC (n = 170), FTC (n = 76), and FA (n = 90) were reported. Follicular variant of PTC and FTC more frequently showed irregular margins, presence of calcifications, "taller than wide" shape, and the absence of halo compared with NIFT-P. Furthermore, FTC and also FA were larger and more frequently hypoechoic than NIFT-P. Most cases (77%) showed an indeterminate cytology. Regardless of the US RSS considered, NIFT-P and FA were less frequently classified in the high-suspicious category compared with FV-PTC and FTC.

CONCLUSIONS

Ultrasound features of NIFT-P are frequently superimposable to those of nodules with low suspicion of malignancy. The NIFT-P is almost never classified in the high-suspicious category according to the main US RSS. Therefore, although the preoperative identification of NIFT-P remains a challenge, neck US can be integrated in the algorithm of management of nodules with indeterminate cytology, suggesting a possible conservative approach in those with low-suspicious features.

Clinico-cytopathological subcategorization in thyroid nodules of atypia of undetermined significance/follicular lesion of undetermined significance using the TIRADS and Bethesda classifications

Introduction

Bethesda category III - atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) is a heterogeneous class of the Bethesda system for thyroid nodules. In order to clarify the therapeutic road for clinicians, this category was subclassified based on the cytopathological features. In this study, we evaluated the risk of malignancy, surgical outcome, demographic characteristics, and correlation of ultrasound features with the final outcome in patients with thyroid nodules based on AUS/FLUS subclassification.

Method

After evaluating 867 thyroid nodules from three different centers, 70 (8.07%) were initially diagnosed as AUS/FLUS. The cytopathologists re-interpreted the FNA samples and subclassified them into five subcategories: architectural atypia, cytologic atypia, cytologic and architectural atypia, and Hürthle cell AUS/FLUS, and atypia, which was not specified. Based on the suspicious ultrasound features, an appropriate ACR TI-RADS score was allocated to each nodule. Finally, the malignancy rate, surgical outcomes, and ACR TI-RADS scores were evaluated among Bethesda category III nodules.

Results

Among the 70 evaluated nodules, 28 (40%) were subclassified as Hürthle cell AUS/FLUS, 22 (31.42%) as cytologic and architectural atypia, 8 (11.42%) as architectural atypia, 7 (10%) as cytologic atypia, and 5 (7.14%) as atypia which was not specified. The overall malignancy rate was 34.28%, and the architectural atypia and Hürthle cell nodules displayed lower malignancy compared to other groups (P-Value<0.05). Utilizing ACR TI-RADS scores showed no statistical significance between Bethesda III subcategorization and ACR TI-RADS scores. However, ACR TI-RADS can be a reliable predictor for Hürthle cell AUS/FLU nodules.

Conclusion

ACR TI-RADS helps evaluate malignancy only in the Hürthle cell AUS/FLUS subcategory of AUS/FLUS. Besides, cytopathological reporting based on the suggested AUS/FLUS subclassification could help clinicians take appropriate measures to manage thyroid nodules.

Noninvasive Follicular Thyroid Neoplasm With Papillary-Like Nuclear Features: What a Surgeon Should Know

The inclusion of the less aggressive follicular form of papillary thyroid cancer (PTC) is associated with an increase in the incidence of the condition, with the follicular variant of PTC being the most common of all variants. The majority of individuals with the encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) are treated as though they have classic thyroid cancer, despite the availability of mounting evidence to contradict the aforementioned. According to numerous research, a certain type of noninvasive-EFVPTC (NI-EFVPTC) demonstrated poor histopathologic diagnostic reproducibility and has received aggressive treatment similar to that of a classical thyroid neoplasm. Therefore, to replace the term NI-EFVPC, a new nomenclature for these tumors, called "noninvasive follicular thyroid neoplasm with papillary-like nuclear characteristics" (NIFTP), was introduced in the year 2016. The present paper explores this recently introduced terminology, clinical, histologic, and molecular features, and diagnostic criteria.

Association between chronic lymphocityc thyroiditis and papillary thyroid carcinoma: Systematic review and meta-analysis of studies on surgical specimens

Introduction. Inconsistent results exist in the literature regarding the hypothesis statement suggesting an increased likelihood of documenting papillary thyroid carcinoma (PTC) in surgical specimens with changes compatible with chronic lymphocytic thyroiditis. Existing meta-analyses have included studies that are not methodologically comparable and do not propose clear sources of bias, thus, this is justification for the present meta-analysis. Methods. A literature search in PubMed and Embase was performed from January 1, 1950 to December 31, 2020. Retrospective studies comparing the prevalence of papillary thyroid carcinoma in specimens with and without chronic lymphocytic thyroiditis changes were obtained. The collected evidence was statistically analyzed. Results. A total of 22 articles were included. The study population consisted of 63,548 surgical specimens. The pooled OR, based on the studies, was 1.81 (95% CI: 1.51-2.21). There was heterogeneity between the distribution of prevalence ratios and opportunity ratios across studies (I²= 91%; p>0.00001). The funnel plot shape of the studies included in the analysis appears to be symmetrical, indicating the absence of bias attributable to small studies. Conclusions. The current literature suggests that there is an increased risk of documenting papillary thyroid carcinoma in surgical specimens in which chronic lymphocytic thyroiditis-compatible changes are observed; however, there are sources of bias that will not be possible to control for in retrospective studies, so we recommend studying the hypothesis suggesting an increased likelihood of diagnosing PTC in specimens with chronic lymphocytic thyroiditis-compatible changes using prospective methodologies.

The combination of BRAFV600E mutation and Chinese Thyroid Imaging Reporting and Data System is helpful in the management of AUS/FLUS thyroid nodules

PURPOSE

To explore the utility of the BRAF^V600E mutation in combination with the Chinese Thyroid Imaging Reporting and Data System (C-TIRADS) in the management of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) thyroid nodule (TN).

METHODS

138 AUS/FLUS TNs in 129 patients were included. Each TN underwent preoperative BRAF^V600E mutation analysis and was classified using the C-TIRADS. Histopathologic diagnosis served as reference standard.

RESULTS

46 benign TNs and 92 malignant TNs were identified. The C-TIRADS 4C and 5 (OR = 10.409, P = 0.000), BRAF^V600E mutation (OR = 36.493, P = 0.000) were independent predictors of malignant nodules. There were significant differences in malignancy rate among the different C-TIRADS TNs (P = 0.000), and these TNs with higher C-TIRADS were associated with increased malignancy rate (P for trend = 0.000). The rate of the nodule with BRAF^V600E mutation increased with the increase of C-TIRADS (P for trend = 0.001). For AUS/FLUS TNs without BRAF^V600E mutation, the malignancy rates of the C-TIRADS 3, 4A, 4B, 4C, and 5 were 0%, 21.4%, 20.8%, 70.8%, and 100%, respectively (P = 0.000), and the malignancy rate increased from C-TIRADS 3 to C-TIRADS 5 (P for trend = 0.000). C-TIRADS and BRAF^V600E mutation had similar diagnostic efficacy (P > 0.05), and the sensitivity, negative predictive value, and accuracy of the combination were significantly higher than BRAF^V600E gene or C-TIRADS alone (P < 0.05).

CONCLUSIONS

C-TIRADS can effectively provide risk stratification for AUS/FLUS nodules. The combination is helpful in selecting appropriate management for AUS/FLUS patients.

Thyroid Nodules with Indeterminate FNAC According to the Italian Classification System: Prevalence, Rate of Operation, and Impact on Risk of Malignancy. An Updated Systematic Review and Meta-analysis

A thyroid nodule classified as indeterminate on fine-needle aspiration cytology (FNAC), hereafter referred to as an indeterminate thyroid nodule (ITN), represents a clinical dilemma. The Italian Consensus for the Classification and Reporting of Thyroid Cytology (ICCRTC) divides ITNs into low- and high-risk categories (i.e., TIR3A and TIR3B, respectively) to better manage patients. This study aimed to achieve high-evidence estimates of the prevalence, rate of operation, and risk of malignancy of ITNs, including TIR3A and TIR3B ITNs. This systematic review was conducted according to MOOSE to retrieve all original studies citing ICCRTC. The last search was performed in February 2022. The risk of bias of the included studies was assessed. Separate proportion meta-analyses were performed with a random-effect model using OpenMeta[Analyst]. The online search processed 271 studies, and 33 were finally considered. First, the cancer prevalence among ITNs was 32.4%. Second, the cancer prevalence among TIR3As was 12.4%, with heterogeneity (I₂ 90%) explained by a linear correlation between sample size and cancer rate (p = 0.009). Third, the cancer prevalence among TIR3Bs was 44.4%, with heterogeneity (I₂ 75%) explained by the inverse correlation between sample size and cancer rate (p = 0.031). Fourth, the prevalence of ITNs, TIR3A, and TIR3B among FNACs was 29.6%, 12.6%, and 12.9%, respectively, with sample size and TIR3B prevalence being inversely correlated (p = 0.04). Fifth, the operation rates of ITNs, TIR3A, and TIR3B were 54.3%, 48.3%, and 75.2%, respectively, and the sample size and TIR3A operation rate were inversely correlated (p = 0.010). These data strongly support the division of ITNs into low- and high-risk subcategories. Importantly for clinical practice, the cancer rate among ITNs is significantly influenced by the study sample size.

Clinicopathologic Characteristics and Postsurgical Follow-Up of Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features in the Postnomenclature Revision Era

Background: Noninvasive encapsulated follicular variant papillary thyroid carcinoma (EFVPTC) was reclassified as "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) in 2016. Most existing studies that examined outcomes included patients managed as EFVPTC and only retrospectively reclassified as NIFTP. This is the first study to evaluate the clinicopathologic, molecular, and surveillance characteristics of patients diagnosed with NIFTP at the time of surgery and managed based on this diagnosis. Methods: We performed a retrospective cohort study of consecutive cases diagnosed as NIFTP from June 2016 to October 2021 identified from electronic medical records at a large tertiary care institution. Patients with coexisting low-risk thyroid cancers ≥1.0 cm in size or any size aggressive histology were excluded, and review of demographic, clinical, imaging, cytologic, and molecular genetic data was performed. Initial care was delivered according to existing clinical guidelines, with a consensus institutional plan for five-year follow-up after surgery. Results: Among 79 patients with 84 nodules diagnosed as NIFTP after surgery, 83.5% (66/79) were women and the mean age was 51 years (range, 21-84). Mean NIFTP size was 2.4 cm (range 0.15-8.0). On ultrasound, the majority of nodules were categorized as thyroid imaging, reporting and data system TI-RADS 3 (55.3%, 42/76), and TI-RADS 4 (36.8%, 28/76). On cytology, they were typically diagnosed as Bethesda III (69.1%, 47/68) or Bethesda IV (23.5%, 16/68). Molecular testing was performed on 62 nodules, and molecular alterations were found in 93.5% (58/62). The most common alterations identified in NIFTP were RAS mutation (75.4%, 43/57), THADA fusion (12.3%, 7/57), and BRAF^K601E mutation (7.0%, 4/57). Fifty-two (65.8%) patients underwent lobectomy and 27 (34.2%) total thyroidectomy, and no patient received completion thyroidectomy. Twenty-one patients (26.5%) had coexisting papillary or follicular microcarcinoma. None of the patients received radioiodine ablation. On a mean follow-up of 28.5 months (range, 6-69 months), no structural or biochemical recurrences were observed. Conclusions: In this large cohort of patients with NIFTP diagnosed at the time of surgery and managed typically by lobectomy with no radioiodine ablation, no evidence of tumor recurrence was identified on a limited follow-up. This finding supports indolent clinical course of NIFTP.

Noninvasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features (NIFTP): Tumour Entity with a Short History. A Review on Challenges in Our Microscopes, Molecular and Ultrasonographic Profile

Since Noninvasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features (NIFTP) was introduced as a new thyroid tumour entity, many studies, and meta-analyses on diagnosing NIFTP have been published. NIFTP-revised histopathological criteria emerged in 2018. NIFTP is defined as a histological entity and its diagnosis requires a careful histological examination. Its molecular profile is similar to follicular-like tumours. Ultrasound features are unable to differentiate NIFTP. NIFTP is not a cytological diagnosis, but it influences the risk of malignancy in several categories of The Bethesda System for Reporting Thyroid Cytopathology terminology.

Large thyroid nodules: should size alone matter?

BACKGROUND

The management of thyroid nodules ≥ 4 cm is controversial due to conflicting evidence on the prevalence of malignancy and diagnostic accuracy of fine-needle aspiration cytology (FNAC). Some literature recommends routine excision of large thyroid nodules due to high cytology false negative rates (FNR). We aim to investigate the diagnostic accuracy of FNAC, prevalence of malignancy in large (≥ 4 cm) thyroid nodules compared to nodules < 4 cm, and the clinical and ultrasound characteristics of those large nodules with false negative cytology.

METHODS

This was a retrospective case-log review in a tertiary referral hospital. All thyroid nodules subjected to Ultrasound (US)-guided FNAC by the Interventional Radiology department between December 2011 and November 2017 were included. Data on patient demographics, thyroid US features, cytology findings, and surgical histology were collected and analyzed. Sensitivity, specificity, and FNR were calculated based on FNAC results and final post-operative histology. Factors associated with a false negative result were analyzed using univariate and multivariate analyses.

RESULTS

A total of 4982 nodules were studied, including 4419 < 4 cm and 563 ≥ 4 cm. Malignancy rates were similar in both groups. For nodules ≥ 4 cm, FNAC sensitivity was 40%, specificity 100%, and FNR 6.6% compared to 4.2% in nodules < 4 cm. Within malignant nodules, there was a significantly higher proportion of follicular and Hurthle cell carcinomas in nodules ≥ 4 cm. Amongst nodules ≥ 4 cm, multivariate analysis revealed male gender to be an independent predictor of FNR (OR 3.32; 95% CI 1.29-8.59).

CONCLUSION

Larger nodules ≥ 4 cm have a similar malignancy rate as nodules < 4 cm, and FNAC FNR is low at 6.6%. Management of large thyroid nodules should be individualized based on their clinical, sonographic and cytological features rather than routine surgery.

LEVEL OF EVIDENCE

3.

The dilemma of 18F-FDG PET/CT thyroid incidentaloma: what we should expect from FNA. A systematic review and meta-analysis

PURPOSE

¹⁸F-FDG thyroid incidentaloma (TI) occurs in ~2% of PET/CT examinations with a cancer prevalence of up to 35-40%. Guidelines recommend fine-needle aspiration cytology (FNA) if a focal ¹⁸F-FDG TI corresponds to a sonographic nodule >1 cm. The aim of this systematic review and meta-analysis was to provide evidence-based data on the diagnostic distribution of ¹⁸F-FDG TIs in the six Bethesda systems for reporting thyroid cytopathology (BETHESDA) subcategories.

METHODS

Original studies reporting ¹⁸F-FDG TIs and cytologically classified according to BETHESDA were included. Six separate meta-analyses were performed to obtain the pooled prevalence (95% confidence interval, 95% CI) of ¹⁸F-FDG TIs in the six BETHESDA subcategories.

RESULTS

Fifteen studies were finally included. Nine studies were from Asian/Eastern and six from Western countries. FNA data according to BETHESDA was available in 2304 cases. The pooled prevalence of ¹⁸F-FDG TIs according to BETHESDA was BETHESDA I 10% (6-14), BETHESDA II 45% (37-53), BETHESDA III 8% (3-13), BETHESDA IV 8% (5-12), BETHESDA V 6% (4-9), BETHESDA VI 19% (13-25). A significantly different prevalence was found in the BETHESDA IV between Asian/Eastern (2%) and Western (19%) studies.

CONCLUSION

Two-thirds of focal ¹⁸F-FDG TIs undergoing FNA have either malignant (BETHESDA VI) or benign (BETHESDA II) cytology while a minority will have indeterminate (BETHESDA III or IV) FNA results. Significant differences between Asian/Eastern and Western studies are also present in the prevalence of indeterminate FNA results.

Reporting Thyroid Cytology in a Globalized World

The Italian SIAPEC-AIT 2014 classification, the 2017 Bethesda System for Reporting Thyroid Cytology (TBSRTC), the 2016 UK Royal College of Pathologists (RCPath) thyroid reporting system, and the 2019 Japanese reporting system for thyroid aspiration cytology (JRSTAC2019) represent the most widely used reporting systems among clinicians and pathologists for the purpose of cytologically diagnosing, estimating the potential risk of malignancy (ROM), and defining the most appropriate treatment for a patient with a thyroid nodule. Although all the systems use overlapping diagnostic categories and morphologic criteria, they differ on the basis of the criteria for inclusion in the cytologic categories, which may, in turn, affect the ROM of a given category and the clinical management of the patient, particularly with regard to the “indeterminate” categories. The aim of this review is to analyze the main differences that emerge between the systems and to propose possible solutions for a comprehensive reporting system that integrates and harmonizes all the criteria of the Italian classification and the Bethesda system, also taking into account the impact that the new tumor entity NIFTP (non-invasive follicular tumor with papillary-like nuclear features) that has, in many instances, replaced the non-invasive form of the follicular variant of papillary carcinoma, has had on the modification of malignancy risks.

Rate of non-invasive follicular thyroid neoplasms with papillary-like nuclear features depends on pathologist's criteria: a multicentre retrospective Southern European study with prolonged follow-up

PURPOSE

To determine the rate of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) in a multi-institutional series from the Iberian Peninsula and describing this NIFTP cohort.

METHODS

Retrospective study of papillary thyroid carcinoma (PTC) or well-differentiated tumours of uncertain malignant potential (WDT-UMP) diagnosed between 2005 and 2015 and measuring ≥5 mm in adult patients from 17 hospitals. Pathological reports were reviewed to determine the cases that fulfil the original criteria of NIFTP and histology was reassessed. Rates were correlated with the number of PTC and its follicular variant (FVPTC) of each institution. Demographic data, histology, management, and follow-up of the reclassified NIFTP cohort were recorded.

RESULTS

A total of 182 cases with NIFTP criteria were identified: 174/3372 PTC (rate: 5.2%; range: 0-12.1%) and 8/19 WDT-UMP (42.1%). NIFTP rate showed linear correlation with total PTC (p: 0.03) and FVPTC (p: 0.007) identified at each centre. Ultrasound findings were non-suspicious in 60.1%. Fine-needle cytology or core biopsy diagnoses were undetermined in 49.7%. Most patients were treated with total thyroidectomy. No case had nodal disease. Among patients with total thyroidectomy, 89.7% had an excellent response evaluated 1 year after surgery. There were no structural persistence or relapses. Five patients showed residual thyroglobulin after 90 months of mean follow-up.

CONCLUSIONS

NIFTP rate is low but highly variable in neighbouring institutions of the Iberian Peninsula. This study suggests pathologist's interpretation of nuclear alterations as the main cause of these differences. Patients disclosed an excellent outcome, even without using the strictest criteria.

Retrospective analysis of cancer-specific gene expression panel for thyroid fine needle aspiration specimens

BACKGROUND

While molecular testing is a promising strategy for preoperative assessment of cytologically indeterminate thyroid nodules, thyroid fine needle aspiration biopsy (FNA) presents unique challenges for molecular assays, including contaminating peripheral blood mononuclear cells (PBMC) and variable numbers of evaluable epithelial thyroid cells. Moreover, the newly recognized entity, noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), has added an additional challenge to the currently available molecular diagnostic platforms. New diagnostic tools are still needed to correctly distinguish benign and malignant thyroid nodules preoperatively.

METHODS

Twenty-two transcript splice variants from 12 genes we previously identified as discriminating benign from malignant thyroid nodules were characterized in 80 frozen thyroid tumors from 8 histological subtypes. Isoforms detectable in PBMC were excluded, and the 5 most discriminating isoforms were further validated by real-time quantitative PCR (qPCR) on intraoperative FNA samples from 59 malignant tumors, 55 benign nodules, and 23 NIFTP samples. The qPCR threshold cycle values for each transcript were normalized to the thyrocyte-specific thyroid peroxidase isoform 1 (TPO1) and z-transformed. Receiver operating characteristic (ROC) analyses of the composite transcript scores were used to evaluate classification of thyroid FNAs by the 5-gene isoform expression panel.

RESULTS

A molecular signature was developed by combining expression levels of specific isoforms of CDH3, FNDC4, HMGA2, KLK7, and PLAG1. FNAs containing at least 12-36 thyrocytes were sufficient for this assay. The 5-gene composite score achieved an area under the ROC curve (AUC) of 0.86 for distinguishing malignant from benign nodules, with a specificity of 91%, sensitivity of 75%, negative predictive value of 91%, and positive predictive value of 74%.

CONCLUSION

Our newly developed 5-gene isoform expression panel distinguishes benign from malignant thyroid tumors and, may help distinguish benign from malignant thyroid nodules in the context of the new NIFTP subtype.

Impact of Molecular Testing on the Management of Indeterminate Thyroid Nodules Among Western and Asian Countries: a Systematic Review and Meta-analysis

Molecular testing has a potential to improve the management of patients with indeterminate thyroid nodules considered for surgery. This study examined the influence of molecular tests on the treatment of indeterminate nodules, particularly the differences between Western and Asian countries. Electronic databases including PubMed and Web of Science were searched for relevant articles from 2010 to March 2019. We computed meta-analysis of proportion and their 95% confidence intervals (CIs) utilizing the random-effect model. We used independent samples t test to compare the resection rate (RR), rate of malignancy (ROM), rate of preoperative molecular testing (RMT), and rate of positive test (RP) between subgroups. We included a total of 34 studies with 7976 indeterminate nodules. The multigene panel testing methods were exclusively used in the USA. Compared with the non-molecular era, molecular testing was associated with a significantly increased ROM (47.9% versus 32.1%; p = 0.001). The ROM of indeterminate nodules in Asian institutes was significantly higher than that in Western countries (75.3% versus 36.6%; p < 0.001, respectively). Institutes employing single-gene tests achieved a higher ROM (59.8% versus 37.9%; p = 0.013). Molecular testing is a promising method to tailor the clinical management for indeterminate thyroid FNA. Certain differences in routine thyroid cytopathology practice among the West and the East are still present. The combination of molecular testing and active surveillance enhances the accuracy of case selection for surgery in Asian countries.

Thyroid FNA terminology: The case for a single unified international system for thyroid FNA reporting

The use of reporting terminologies for thyroid FNA cytology enables standardisation and international alignment of the reporting of thyroid cytology results, which is essential. There are currently three major internationally recognised systems: Bethesda (TBS), UK RCPath (Thy), and Italian (TIR). A fourth terminology system used in Japan has identical categories to TBS but with different nomenclature. The aim of this review is to discuss the strengths and weaknesses of the TBS, UK RCPath, and TIR systems, and to make the case for international terminology harmonisation and standardisation.

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.

Three ultrasound phenotypes of non-invasive follicular thyroid neoplasm with papillary-like nuclear features proposed for imaging-pathology analysis: single center experience

Background

The terminology "non-invasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) was introduced to reduce overtreatment of thyroid carcinomas with indolent behavior. However, limited literature discussed the sonographic features of the entity in depth. The objective of this study is to summarize sonographic subtypes of NIFTP for precise diagnosis.

Methods

From January 2017 to June 2020, 13,531 consecutive patients underwent surgery for thyroid nodules were reviewed; 30 patients (0.22%) with 30 NIFTP were eligible for this retrospective observational study. We evaluated ultrasound features of all the lesions and distributed them into 3 major types of ultrasound appearance using pattern recognition. Systemic literature review concerning ultrasonography of NIFTP was also performed.

Results

At sonography, all the NIFTP lesions were classified into three types: 19 (63.3%) were categorized into type A-oval and solid nodule without other high-suspicion features, 7 (23.3%) into type B-partially cystic mass without high-suspicion features, 4 (13.3%) into type C-hypoechoic solid nodule with high-suspicion features including irregular margins, microcalcifications, taller-than-wide shape.

Conclusions

Three ultrasound patterns were proposed by us for ultrasound-cytopathology correlation analysis.

Thyroid fine-needle aspiration trends before, during, and after the lockdown: what we have learned so far from the COVID-19 pandemic

PURPOSE

Nowadays, the clinical management of thyroid nodules needs to be multi-disciplinary. In particular, the crosstalk between endocrinologists and cytopathologists is key. When FNAs are properly requested by endocrinologists for nodules characterised by relevant clinical and ultrasound features, cytopathologists play a pivotal role in the diagnostic work-up. Conversely, improper FNA requests can lead to questionable diagnostic efficiency. Recently, recommendations to delay all non-urgent diagnostic procedures, such as thyroid FNAs, to contain the spread of COVID-19 infection, have made the interplay between endocrinologists and cytopathologists even more essential. The objective of this study was to assess the impact of COVID-19 pandemic on our practice by evaluating the total number of FNAs performed and the distribution of the Bethesda Categories before, during, and after the lockdown.

METHODS

We analysed the FNA trends before (1st January 2019 to March 13th 2020), during (March 14th to May 15th), and after (May 16th to July 7th) the lockdown.

RESULTS

Although the total number of weekly FNAs dropped from 62.1 to 23.1, our referring endocrinologists managed to prioritise patients with high-risk nodules. In fact, in the post-lockdown, the weekly proportion of benign diagnoses dropped on average by 12% and that of high-risk diagnoses increased by 6%.

CONCLUSIONS

The lesson we have learned so far from this pandemic is that by applying safety protocols to avoid contagion and by increasing the threshold for FNA requests for thyroid nodules, we can continue to guarantee our services to high-risk patients even in times of a health crisis.

Case Report: Multifocal non-invasive follicular thyroid neoplasm with papillary-like nuclear features presenting in a female child

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was introduced as a separate entity by the World Health Organization in 2017 with strict inclusion and exclusion criteria.  Most NIFTP cases have been reported in adults and few cases have been diagnosed in children. Here, we present a classic case of NIFTP affecting a 10-year old female child. We also review previous reports of NIFTP in children regarding size, focality, nodal metastasis, recurrence, type of operation and follow-up data. The present report adds a new case of NIFTP in the paediatric age group characterized by multifocality, absence of nodal invasion and indolent course until last follow-up, recommending less aggressive management.

Measures to reduce diagnostic error and improve clinical decision making in thyroid FNA aspiration cytology: A proposed framework

Thyroid fine-needle aspiration cytology (FNA) and histopathology can be subjective areas of medical diagnosis and subject to different interpretations. On the basis of the authors' personal experience, 12 recommendations with potential to improve clinical decision making, ensure quality, and reduce diagnostic error in thyroid FNAC and histopathology are presented. 1) use a standardized reporting terminology for thyroid FNAC; 2) understand and explain to service users the limitations of cytology and the standardized thyroid FNAC reporting terminology used; 3) the cytopathologist should review all relevant clinical and ultrasound findings, if feasible; 4) include the risk of malignancy in all FNAC reports if feasible; 5) collect data to calculate the local institutional risk of malignancy for FNAC if feasible; 6) accept that nondiagnostic FNAC will include small numbers of carcinomas; 7) use rapid on-site evaluation and/or educational sessions for aspirators if the nondiagnostic aspiration rate is high; 8) know the diagnostic pitfalls of both cytology and histopathology; 9) use special immunohistochemical and molecular techniques that are evidence-based; 10) make use of second opinions, either in-house or interinstitutional; 11) multidisciplinary discussion of cases before surgery or therapy is invaluable; and, finally, 12) manage patient and clinician expectations of thyroid cytology and histopathology. These 12 recommendations may assist in quality-improvement initiatives and may reduce diagnostic errors in thyroid cytology and histopathology. Thyroid multidisciplinary case discussion remains the principal, overarching method for error reduction and for providing high-quality clinical decision making.

Did Introducing a New Category of Thyroid Tumors (Non-invasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features) Decrease the Risk of Malignancy for the Diagnostic Categories in the Bethesda System for Reporting Thyroid Cytopathology?

In 2016, Nikiforov et al. (JAMA Oncol 2:1023-1029, 2016) proposed replacing the term "non-invasive encapsulated follicular variant of papillary thyroid carcinoma" (FVPTC) with the term "non-invasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP). In 2018, to avoid the misdiagnosis of papillary thyroid cancer as NIFTP, the authors proposed changes to the criteria for NIFTP classification. Some previous studies evaluated the impact of NIFTP on the risk of malignancy (ROM) in the fine-needle aspiration cytology (FNAC) diagnostic categories according to the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). However, little is known about the influence of an NIFTP diagnosis on ROM on the basis of the revised criteria. The aim of this study was to assess the influence of NIFTP on ROM using the revised diagnostic criteria. The present study included 998 thyroid nodules that were diagnosed and resected at the same medical center. All specimens with a diagnosis of cancer were reviewed to identify NIFTP according to the revised 2018 criteria. Additionally, molecular diagnostics were performed to detect the BRAF p.V600E mutation and TERT promoter mutations in all the NIFTP cases. The number of cases that met the revised criteria was determined, and the ROM was calculated in each of the FNAC diagnostic categories. Only five cases (2.3% of all papillary thyroid carcinoma diagnoses) were considered NIFTP, according to the 2018 criteria. With respect to the FNAC category, one case was a follicular neoplasm or suspicious for a follicular neoplasm (FN/SFN), three cases were suspicious for malignancy (SM), and one case was malignant (M). The ROM decreased in each of the Bethesda categories (0.7% in FN/SFN, 4.3% in SM, and 0.5% in M) when a diagnosis of NIFTP was taken into account. These reductions were not statistically significant. These data indicate that the NIFTP entity has very little impact on ROM for the diagnostic categories of the Bethesda system.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features and the risk of malignancy in The Bethesda System for the Reporting of Thyroid Cytopathology

INTRODUCTION

The Bethesda System for the Reporting of Thyroid Cytopathology (TBSRTC) is used to categorize and diagnose thyroid nodules by fine needle aspiration biopsy (FNAB). Each category in TBSRTC is associated with an estimated risk of malignancy (ROM). A subset of noninvasive encapsulated follicular variant of papillary thyroid carcinoma (niEFVPTC) was reclassified as a nonmalignant tumor: noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). We studied the impact of this reclassification on the reported ROM in TBSRTC.

MATERIAL AND METHODS

We searched our institutional files for thyroid FNAB with surgical follow-up. ROM for each TBSRTC category was calculated. Subsequently, cases of niEFVPTC were reviewed and reclassified as NIFTP, if appropriate. ROM for each category was then recalculated after the reclassification.

RESULTS

Twenty-six NIFTP were identified; the corresponding FNABs were distributed among all six TBSRTC categories. The majority of NIFTP FNAB were in the AUS/FLUS and suspicious for malignancy (SUSP) categories, 12 (46.2%) and 8 (30.8%), respectively. While the ROM changed for all diagnostic categories, the greatest change in ROM after reclassification was seen in these two categories. Absolute ROM for AUS/FLUS decreased from 25.0% to 21.0% and SUSP, from 71.7% to 58.3%, changes that were statistically significant.

CONCLUSIONS

The reclassification of niEFVPTC to NIFTP has significantly impacted the ROM in the TBSRTC at our institution. While there was a decrease in ROM for all categories, the greatest reduction to ROM was in the categories of AUS/FLUS and FN. These changes to the ROM should help guide surgical approach moving forward.

Risk of Malignancy (ROM) of Thyroid FNA Diagnosed as Suspicious for Malignancy or Malignant: an Institutional Experience with Systematic Review and Meta-Analysis of Literature

A universal recommendation does not exist for thyroid FNA suspicious for malignancy (SFM). In this context, the guidelines have estimated a risk of malignancy (ROM) from 50 to 80% and both total thyroidectomy and lobectomy may be indicated. This study aimed to (1) retrospectively evaluate the SFM (i.e., TIR4) in a single institution to estimate their cancer prevalence at histology, and (2) systematic review the literature to obtain more robust information. The study period was 2015-2018. As a major inclusion criterion, both cytology and histology had to be performed in our institution. Histological diagnosis was the gold standard. For the systematic review, the online databases of Google Scholar, PubMed/MEDLINE, and Scopus were searched for papers using the same classification for thyroid FNA. A proportion meta-analysis was performed to obtain the pooled histological cancer rate among TIR4 and TIR5 (random-effects model). In the institutional database, there were 271 nodules with both histology and FNA and the cancer rate of TIR4 was 88.9%. By systematic review, five studies were selected for the meta-analysis. The pooled cancer rate was 85% in TIR4 and 99% in TIR5 (I² = 0%; no publication bias). In conclusion, these new findings should prompt the guidelines board to fully revise the estimated ROM of SFM category. Clinical thyroidologists and thyroid surgeons should be aware of these data and the patients with SFM should be informed of their ROM.

Testing for BRAF (V600E) Mutation in Thyroid Nodules with Fine-Needle Aspiration (FNA) Read as Suspicious for Malignancy (Bethesda V, Thy4, TIR4): a Systematic Review and Meta-analysis

In patients with thyroid fine-needle aspiration (FNA) report of suspicious for malignancy (SFM), both lobectomy and thyroidectomy might be considered. BRAF mutation analysis could guide towards accurate surgical therapy. The primary outcome was the reliability of BRAF (V600E) in detecting malignancy in nodules with FNA reading of SFM. The secondary outcome was to analyze its positive predictive value (PPV) and negative predictive value (NPV) considering the surgical histology as gold standard. A literature search of online databases was performed in June 2019. BRAF prevalence among thyroid nodules with FNA read as SFM according to the most popular classification systems (i.e., Bethesda V, Thy4, TIR4 category) was searched. The random-effects model was used. Three hundred sixty original articles were identified and 34 were finally included in the study. There were 1428 thyroid nodules with FNA read as SFM and 1287 (90.1%) lesions underwent surgery with a cancer rate 89.6%. The pooled prevalence of BRAF (V600E) mutation among all nodules with SFM cytology was 47% (95% CI = 40 to 54, I2 = 85.5%). Pooled PPV and NPV of BRAF testing were 99% (95% CI, 97-99) and 24% (95% CI, 16-32), respectively. BRAF (V600E) mutation was found in about one in two nodules with thyroid FNA read as SFM, its PPV to detect cancers was excellent, and its NPV was very poor. The routine BRAF testing in FNA read as SFM cannot be recommended. BRAF (V600E) test may be useful to extend surgical approach in selected cases with further suspicious clinical/ultrasound features.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features: a problematic entity

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a borderline thyroid tumour formerly known as noninvasive encapsulated follicular variant of papillary thyroid carcinoma. The prevalence of NIFTP is estimated at 4.4-9.1% of all papillary thyroid carcinomas worldwide; however, the rate of occurrence of NIFTP is eight times lower in Asian countries than in Western Europe and America. At the molecular level, NIFTP is characterised by the lack of BRAF V600E and BRAF V600E-like mutations or other high-risk mutations (TERT, TP53), and a high rate of RAS mutations, which is similar to other follicular-pattern thyroid tumours. The diagnosis of NIFTP can only be made after histological examination of the entire tumour removed during surgery, and is based on strictly defined inclusion and exclusion criteria. Although the diagnosis is postoperative, the combination of certain findings of preoperative tests including ultrasonography, cytology, and molecular testing may raise suspicion of NIFTP. These tumours can be effectively treated by lobectomy, although total thyroidectomy remains an option for some patients. Radioactive iodine and thyroid stimulating hormone suppression therapy are not required. NIFTP has an extremely good prognosis, even when treated conservatively with lobectomy alone. Nevertheless, it cannot be considered as a benign lesion. The risk of adverse outcomes, including lymph node and distant metastases, is low but not negligible.

Long-term progression of non-invasive follicular thyroid neoplasm with papillary-like nuclear features: A single-center retrospective study of the French Marne-Ardennes thyroid cancer registry

CONTEXT

Non-invasive forms of encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) were reclassified as non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) in order to reduce overtreatment. A few studies showed neck lymphadenopathy at diagnosis, or even distant metastasis in patients with NIFTP.

OBJECTIVE

Our aim was to report the frequency, clinical features and long-term progression of histologically confirmed NIFTP, using data from the French Marne-Ardennes thyroid cancer registry, and to compare findings against FVPTC.

METHODS

This was a retrospective study on data for follicular variant of PTC (FVPTC) diagnosed between 1975 and 2015 obtained from the specialized Marne-Ardennes thyroid cancer registry. Pathology reports were used to select appropriate cases from a large series, and FVPTC specimens were reviewed by endocrine pathologists. Strict diagnostic criteria were used for reclassification as NIFTP.

RESULTS

In total, 115 cases were reviewed histologically out of 383 cases of FVPTC. Sixty-five met all criteria for NIFTP and were consequently reclassified. Incidence of NIFTP was 16.9% of cases of FVPTC. Fifty patients were women (76.9%); median age was 47 years. Mean NIFTP size was 2.6 cm. There were no significant differences in age, gender or tumor size between NIFTP and FVPTC. Fifty patients underwent total thyroidectomy and 15 lobectomy. There were no lymph node metastases at diagnosis, and none of the patients (N=17) who underwent central and/or lateral neck dissection had positive findings on microscopic examination. 46 patients (70.8%) received radioiodine (RAI). Patients were followed up for 1.9-27.3 years (median 14.6 years) after initial treatment. All patients remained in complete remission during follow-up.

CONCLUSION

Consistently with previous studies, our results showed the indolent course of NIFTP and that risk of recurrence after complete resection is very low (zero in our cohort), even when size is ≥4cm and in absence of adjuvant RAI treatment. Prospective studies are needed to confirm those results.

Ultrasound and cytological characteristics of non-invasive follicular thyroid neoplasm with papillary-like nuclear features compared to papillary carcinomas

INTRODUCTION

NIFTP (non-invasive follicular thyroid neoplasm with papillary-like nuclear features, formerly non-invasive encapsulated follicular variant of papillary thyroid carcinoma) has been removed from the carcinoma category because of its indolent character and good prognosis. This change impacts clinical and surgical management, since these tumors no longer require total thyroidectomy, or complementary radioactive iodine therapy for <4cm tumor. The aim of the present study was to identify preoperative ultrasound and cytological differences between NIFTP and papillary thyroid carcinoma (PTC).

MATERIALS AND METHODS

A retrospective study included 81 patients who underwent total thyroidectomy or thyroid lobectomy with histologic diagnosis of PTC, NIFTP or invasive follicular variant of PTC (IFVPTC) between January 1st, 2016 and May 31st, 2018. Ultrasound and cytological data were analyzed and compared between NIFTP and non-NIFTP (PTC and invasive follicular variant of PTC).

RESULTS

Fourteen NIFTPs, 67 PTCs, including 20 IFVPTCs, were included. In comparison with non-NIFTP PTC, nodules in NIFTP were more often isoechoic (69.2% vs. 17.4%; P=0.0007), with smooth borders (92.3% vs. 31.1%; P=0.0001) and TI-RADS score 2, 3 or 4a. Cytologically, NIFTPs were mainly in categories AUS/FLUS, FN and SusM of the Bethesda System for Reporting Thyroid Cytopathology. Only nuclear pseudo-inclusions were significantly associated with non-NIFTP (P=0.0031).

CONCLUSION

NIFTP appears non-suspect on preoperative ultrasound and indeterminate on cytology. These differences with respect to PTC can guide diagnosis and surgical treatment.

Rapid On-site Molecular Evaluation in thyroid cytopathology: A same-day cytological and molecular diagnosis

BACKGROUND

Thyroid fine-needle aspirates (FNAs) with undetermined morphology can be outsourced to centralized laboratories for comprehensive molecular profiling. When a local, rapid screening rules out easily detectable BRAF and NRAS mutations outsourcing is minimized, leading to cost savings. The fully automated Idylla technology, that does not require trained staff, is an emerging option. However, Idylla platform has only been validated to process formalin fixed paraffin embedded (FFPE) sections. Here we investigate whether also the FNA needle rinse could be genotyped by the same cytopathologist who performs the FNA, a procedure that can be termed rapid on site molecular evaluation (ROME).

METHODS

To validate this approach, the Idylla BRAF and NRAS Test was performed on the rinses from 25 simulated (bench-top) FNAs, in a first part of the study. Genotyping data were compared with those obtained on matched histological FFPE blocks. The second part of the study was carried out on 25 prospectively collected routine FNAs to assess the performance of the Idylla BRAF and NRAS assay against a gold standard real time polymerase chain reaction method.

RESULTS

Idylla NRAS-BRAF Mutation Test was performed on needle rinse as well as histological FFPE blocks. A sensitivity of 88.9%, a specificity of 100.0% were obtained comparing the Idylla NRAS-BRAF Mutation Test on needle rinse to the reference method.

CONCLUSIONS

The FNA needle rinse can be directly genotyped. This obviates the need of cell block preparation, making possible a rapid combined morphological and molecular evaluation. Since DNA extraction is no longer necessary, the cytopathologist can perform ROME him/herself.

Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features: From Echography to Genetic Profile

In thyroid pathology, the great variety of types and the wide range of aggressiveness of thyroid cancers complicate both diagnosis and management. In 2016, a subset of noninvasive encapsulated follicular variant of papillary thyroid carcinoma was reclassified as noninvasive follicular thyroid tumor with papillary-like nuclear features (NIFTP) to reduce overtreatment of this low-risk tumor that follows a benign course after surgery. Starting from a paradigmatic clinical case, in this short review, we will summarize the ultrasonography, cytological, histological and molecular features of this new entity. In the preoperative settings, the recognition of some peculiar elements may only suggest the possibility of a NIFTP, thus favoring a less aggressive surgical approach. However, the diagnosis of NIFTP can only be made after complete resection of the lesion by detecting well-defined inclusion and exclusion histopathological criteria. Since NIFTP is not 'malignant,' surgery may be considered curative with no further treatment or surveillance needed. NIFTP-related issues, including nodule size, multifocality, oncocytic changes, heterogeneous incidence across different geographical areas and its occurrence in the pediatric age, will be discussed.

Prognosis of patients with differentiated thyroid carcinomas having a preoperative cytological report of indeterminate at low or high risk. A multicenter study

BACKGROUND

Italian cytology system for thyroid fine-needle aspiration (FNA) includes indeterminate lesions at low- (Tir 3A) and high-risk (Tir 3B). The present retrospective multicenter study was undertaken to compare the histological type of cancers and disease-free survival in these two groups.

METHODS

Eight institutions participated. Thyroid cancer patients diagnosed and followed-up after Tir 3A or Tir 3B were reviewed. Histological diagnosis was adopted as the gold standard. Patients were defined with cancer recurrence or no evidence of disease. Disease-free survival (DFS) was calculated. A non-parametric statistical analysis was used. DFS was estimated by Kaplan-Meier method and Hazard Ratio (HR) defined the slope of curves.

RESULTS

Two hundred and nine patients (median DFS 24 months) were enrolled and a 6.3% of these recurred. Tir 3B group had higher age (p = 0.014), larger cancer size (p = 0.0002), shorter DFS (p = 0.003), higher number of aggressive cancers (p = 0.006), and relapse frequency double than Tir 3A. At survival curves analysis, Tir 3B group had HR of 2.37 with respect to Tir 3A. At Cox's proportional hazard regression analysis histology was the only significant predictor of relapse.

CONCLUSIONS

While patients with thyroid FNA of Tir 3B should be addressed to surgery due to high likelihood of more aggressive cancer, a diagnostic surgery could be avoided in patients with Tir 3A if concurrent unsuspicious clinical features are found.

The Role of Molecular Testing for the Indeterminate Thyroid FNA

Thyroid nodules are common in the adult population where a majority are benign and only 4.0% to 6.5% are malignant. Fine needle aspiration (FNA) is a key method used in the early stages to evaluate and triage patients with thyroid nodules. While a definitive cytological diagnosis is provided in more than 70–75% of all thyroid FNA cases, the group of indeterminate lesions offers a challenge in terms of interpretation and clinical management. Molecular testing platforms have been developed, are recognized as an option by the 2015 American Thyroid Association Guidelines, and are frequently used in conjunction with FNA as an integral part of the cytologic evaluation. In this review, the utility of molecular testing options for nodules assigned to the group of indeterminate thyroid FNAs is described.

Clinical-pathological issues in thyroid pathology: study on the routine application of NIFTP diagnostic criteria

In 2017, the WHO classification of tumours of the endocrine organs established the criteria for a NIFTP diagnosis. The present paper considers some aspects that are still debated or unresolved: the real incidence and clinical meaning of multifocal/multinodular lesions, the biological behaviour of micro-NIFTP, the sprinkling phenomenon and the corresponding modifications to the FNA reporting systems based on changes to the ROM. Moreover, the paper suggests possible scenarios for the clinical-pathological management of this entity. From the initial 1470 cases, a group of 68 NIFTPs was recruited in a 9 year-long period. The average age at diagnosis was 55 years. The average diameter of the lesion was 1.7 cm (0.1 cm–10 cm). In 41 cases (60.1%), the lesion was inserted in the context of a multinodular background. In 12 cases, the diagnosis was incidental and the pre- operative FNA was performed on a different target. In 10 out of 68 cases, there was a multifocal NIFTP; in 14.7% of patients, PTC-like nuclear features showed sprinkling phenomenon. The cytological revision allocated 21 cases (49%) to the SIAPEC TIR3 indeterminate class and a nuclear score 2 or 3 were identified in 25 smears. Multifocality is part of the spectrum of NIFTPs, that can arise in a multinodular background with variable sizes from microscopic lesions to very large ones. Cytopathological criteria such as an evaluation of the nuclear score may help the pathologists in promoting a NIFTP diagnosis in the preoperative setting.

Approach to cytological indeterminate thyroid nodules

The indeterminate thyroid nodules diagnosed by fine-needle aspiration cytology (FNAC)represents a problem for both cytopathologists and clinicians. The former sometimes use this diagnostic category as a sort of basket, putting in cases that they do not know exactly how to classify. The latter are faced with a highly variable risk of malignancy and consequently the management remains a challenge. On the histopathological side, the new WHO classification of tumors of the thyroid introduced the concept of tumors with uncertain and low malignant potential, and the concept of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), whose prognosis and management are still to be completely elucidated. While the risk of malignancy of the indeterminate diagnostic category has decreased due to the re-classification of certain types of papillary thyroid carcinomas of the follicular variant into a low malignant potential form (the NIFTP), cases diagnosed cytologically as indeterminate will probably increase in the future to avoid false positive diagnosis. Thus, the indeterminate thyroid diagnostic category still remains a challenge, both at the diagnostic level and for its management. The new version of the Bethesda system for reporting thyroid cytopathology suggests managing these patients with a repeat FNA, diagnostic lobectomy and/or molecular testing.

Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP): Update and Diagnostic Considerations-a Review

Advances in our understanding of thyroid lesions, especially those entities with an indolent behavior, has led clinicians to question the most appropriate surgical management of such thyroid nodules. Several studies have shown that the non-invasive encapsulated follicular variant of papillary thyroid carcinomas (NI-EFVPC) exhibits poor histopathologic diagnostic reproducibility and have been over-treated as conventional thyroid cancer. In 2015, an international thyroid working group re-evaluated NI-EFVPC and its diagnostic criteria. The new terminology of "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) was accordingly introduced to replace NI-EFVPC. The literature has emphasized that NIFTPs are biologically similar to follicular adenomas lacking lymph node metastases and/or recurrence. While the definition of NIFTP is based on specific morphological parameters, recent studies have questioned whether the criterion allowing less than 1% of true papillae should be revised to a total absence of papillae. The motivation for this revision is the rare finding, in some studies, of lymph nodes with metastatic NIFTP. This review evaluates the existing published series of NIFTP cases, clinical consequences of NIFTP, and emerging changes in the diagnostic criteria for NIFTP. The introduction of NIFTP has resulted in significant impact on the clinical management of thyroid nodules. Recent revisions in the morphological criteria for NIFTP emphasize the need to adhere to very stringent histomorphologic criteria when making a diagnosis of NIFTP. The adoption of NIFTP terminology instead of NI-EFVPC is associated with conservative lobectomy without radioactive iodine treatment in the majority of cases.

[Tumors of the thyroid gland. Proposal for the management and study of samples from patients with thyroid neoplasms]

The recent changes in the classification and staging of thyroid tumors have arisen from the need to provide an adequate response to the exponential increase of thyroid cancer, which, however, has not been accompanied by an increase in mortality. These changes pretend to reduce overdiagnoses of malignancy, unnecessary treatment, side effects as well as cost for the health system. To this end, this article reviews recommendations for the management of thyroid surgical pathology samples with emphasis on the new terminology of the WHO classification. The basic criteria for the diagnosis of malignancy in well-differentiated thyroid carcinomas are reviewed and the criteria for NIFTP (non-invasive follicular tumor with papillary-like nuclear features) diagnosis are updated. Recommendations for the elaboration of the pathological report are also included.