Follicular Thyroid Neoplasm Research Articles

Binary subclassification scheme (AUS-Nuclear versus AUS-Other) adequately risk-stratifies thyroid fine needle aspiration specimens classified as Atypia of Undetermined Significance

The Bethesda System for Reporting Thyroid Cytopathology previously described 4subclassesof atypia within the Atypia of Undetermined Significance (AUS) category: nuclear (AUS-Nuc), architectural (AUS-A), oncocytic (AUS-Onc), and atypia not otherwise specified (AUS-NOS). Accumulating evidence supports a binary AUS subclassification scheme based primarily on the presence of nuclear atypia only. The purpose of this study is to compare the risk stratification of binary versus 4-tier AUS subclassification systems among AUS nodules with molecular and/or histologic follow-up. Thyroid aspirates classified as AUS and tested using Afirma (Veracyte, Inc.) between 6/2013 and 7/2021 were included. For resected nodules, histological classification was considered as the final outcome. For unresected nodules, benign Afirma results were considered low-risk outcomes, similar to histologically benign nodules. Suspicious or nondiagnostic Afirma results were considered indeterminate outcomes. The prevalence of outcomes warranting surgery (noninvasive follicular thyroid neoplasm with papillary-like nuclear features [NIFTP] or cancer) was calculated for each AUS subclass. A total of 559 AUS nodules with Afirma testing were identified. Excluding nodules with indeterminate molecular outcomes, NIFTP/cancer prevalence for AUS-Nuc was 21% (57/266), which was higher than that for AUS-A (6%, 11/188), AUS-Onc (8%, 4/53), and AUS-NOS (0%, 0/9). A binary AUS subclassification scheme based on nuclear atypia showed a significant difference in NIFTP/cancer prevalence (21% versus 6%, P < 0.0001). Binary reporting of AUS subclasses based on nuclear atypia distinguishes cases with a higher risk of NIFTP/cancer. There is a low but non-negligible prevalence of NIFTP/cancer in cases without nuclear atypia.

Genomic and transcriptomic analyses of thyroid cancers identify DICER1 somatic mutations in adult follicular-patterned RAS-like tumors.

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer (TC). Several genomic and transcriptomic studies explored the molecular landscape of follicular cell-derived TCs, and BRAFV600E, RAS mutations, and gene fusions are well-established drivers. DICER1 mutations were described in specific sets of TC patients but represent a rare event in adult TC patients. Here, we report the molecular characterization of 30 retrospective follicular cell-derived thyroid tumors, comprising PTCs (90%) and poorly differentiated TCs (10%), collected at our Institute. We performed DNA whole-exome sequencing using patient-matched control for somatic mutation calling, and targeted RNA-seq for gene fusion detection. Transcriptional profiles established in the same cohort by microarray were investigated using three signaling-related gene signatures derived from The Cancer Genome Atlas (TCGA). The occurrence of BRAFV600E (44%), RAS mutations (13%), and gene fusions (13%) was confirmed in our cohort. In addition, in two patients lacking known drivers, mutations of the DICER1 gene (p.D1709N and p.D1810V) were identified. DICER1 mutations occur in two adult patients with follicular-pattern lesions, and in one of them a second concurrent DICER1 mutation (p.R459*) is also observed. Additional putative drivers include ROS1 gene (p.P2130A mutation), identified in a patient with a rare solid-trabecular subtype of PTC. Transcriptomics indicates that DICER1 tumors are RAS-like, whereas the ROS1-mutated tumor displays a borderline RAS-/BRAF-like subtype. We also provide an overview of DICER1 and ROS1 mutations in thyroid lesions by investigating the COSMIC database. Even though small, our series recapitulates the genetic background of PTC. Furthermore, we identified DICER1 mutations, one of which is previously unreported in thyroid lesions. For these less common alterations and for patients with unknown drivers, we provide signaling information applying TCGA-derived classification.

SAT556 An Unusual Case of Papillary Thyroid Carcinoma With Biallelic MEN1 Variants In a Patient With MEN1

Abstract Disclosure: E. Chuki: None. M. Raffeld: None. J. Klubo-Gwiezdzinska: None. S. Gubbi: None. S. Jha: None. Introduction: Multiple endocrine neoplasia (MEN1) syndrome is caused by germline variants in MEN1. Papillary Thyroid Cancer (PTC) is not regarded as a canonical MEN1-related endocrine tumor. Pathogenic variants in MEN1 are rare in PTC. Herein, we report an MEN1 patient with biallelic loss of MEN1 in PTC.Clinical case: A 59-year-old Hispanic female presented with asymptomatic hypercalcemia due to primary hyperparathyroidism [serum calcium: 13.9 mg/dl (8.4-10.2), PTH: 314 pg/ml (15-65) and 25 hydroxy vitamin D: 15 ng/ml (33 – 100)]. Physical examination was unrevealing for any neck mass or lymph nodes. Kidney function was normal with no history of or imaging evidence of kidney stones or calculi. Bone densitometry revealed osteoporosis [lowest T-score of -2.7 in spine]. Germline genetic testing was performed given large size of the parathyroid tumor and biochemical presentation suspicious for parathyroid cancer. A pathogenic MEN1 p.Ile54Serfs*65 was identified. A neck sonogram and 99-technetium sestamibi scan showed a 4.1 cm left parathyroid adenoma and incidental 3.5 cm, heterogeneous right thyroid lobe nodule having smooth margins without microcalcifications, and no cervical lymphadenopathy. Thyroid function studies were normal. Fine needle aspiration of right thyroid nodule revealed epithelial neoplasia containing many atypical cells with enlarged nuclei, nuclear grooves, fine chromatin, and moderate amounts of granular to oxyphilic cytoplasm. Patient underwent left inferior parathyroidectomy and right thyroid lobectomy. Histology was consistent with parathyroid adenoma and a hyperplastic adenomatous thyroid nodule with a 1.1 cm focus of classic PTC with minor follicular and oncocytic components, limited to the thyroid with clear margins and no lymphovascular invasion (pT1bNxMx). Genetic sequencing of the PTC (TSO500 gene panel) revealed two pathogenic frameshift variants in MEN1 p.I54fs*65 and p.D33fs*82 at variant allele frequency (VAF) of 53% and 42% respectively, TERT promoter (TERTp) variant [C228T (c.-124C&amp;gt;T)] at VAF of 44.8% and an NRAS p.Q61K variant at VAF of 39%. The two MEN1 variants were in trans to each other on opposite alleles, suggestive of a second-hit leading to a loss of biallelic function of MEN1.Conclusion: PTC in MEN1 has been rarely reported in the literature [1]. However, per our knowledge, this is the first report of a PTC with second-hit in the MEN1 gene. Somatic MEN1 pathogenic variants have been reported in occasional cases of thyroid oncocytic tumors and NRAS is more frequently associated with follicular or oncocytic thyroid tumors. Thus, whether this tumor should be regarded as a rare manifestation of the MEN1 syndrome is unclear. The histopathologic and molecular characteristics of thyroid tumors in MEN1 warrant further investigation. Reference: 1. Desai et al. Ann Surg Oncol 2001;8(4):342-6. Presentation Date: Saturday, June 17, 2023

SAT476 A Case of Thyroid Hemiagenesis

Abstract Disclosure: P. Kachhadia: None. S. Khan: None. S. Aldasouqi: None. A. Abu Limon: None. Introduction: Thyroid hemiagenesis is congenitally rare, in which one side of the thyroid does not develop. Hemiagenesis is more common with an absent left thyroid lobe, at a 4:1 ratio. Though prevalence is sited at 0.05%, actual incidence of hemiagenesis amongst the population is unknown as most patients are euthyroid and asymptomatic. We present a case of a patient who was referred to our clinic for unilateral thyroid enlargement on physical exam. Thyroid Ultrasound (US) was done which showed an absent left thyroid lobe along with enlarged right thyroid lobe and hypervascularity. There was also an incidental thyroid nodule noted on US. Case Presentation: Patient is a 38 year old female who presented to the clinic 4 years prior for enlarged thyroid nodule noted on ultrasound. With symptoms of dysphagia and a visibly enlarged gland, an US with labs was prompted by her primary physician. US showed absent left thyroid lobe and right lobe enlargement with hypervascularity and incidental subcentimeter nodule. Clinically and biochemically, the patient was euthyroid. Singular right lobe was verified on clinic real time ultrasound and on NM uptake scan. The 24 hour uptake was at 30.5%, with the upper limit of normal being 30%. With increased uptake and hypervascularity, thyroid stimulating immunoglobulin and thyrotropin receptor antibodies were checked and were not detected. It was thought that the right thyroid gland enlargement and hypervascularity were compensatory due to the left hemiagenesis. The thyroid nodule was monitored, and within 3 years of original imaging, it enlarged to 0.98 x 0.59 x 0.39 cm, with TI-RADS 5 assessment per ACR criteria. Patient chose to undergo thyroid biopsy which showed Bethesda III, Follicular Lesion of Undetermined Significance (FLUS). Microscopy showed follicular cells arranged in microfollicles and crowded groups with round, enlarged, irregular nuclei and overlapping nucleoli. Intranuclear chromatin clearing and intranuclear grooves are present. Background is hemorrhagic with minimal colloid. Molecular Thyroseq testing was at 5-10% chance of malignancy or noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). Genetic markers were only positive for copy number alterations. Discussion: Thyroid Hemiagenesis, though rare, has been associated with other thyroid pathologies such as hypothyroidism, hyperthyroidism and thyroid malignancies. Genetic studies have not found a common background within cases reported. As these patients are more likely to incur additional thyroid pathologies, questions still remain as to the clinical management and outcome of such patients. Due to concerning cytological features for PTC, the patient was offered right thyroidectomy and will be looking to make a decision in the near future. Presentation Date: Saturday, June 17, 2023

Investigation of pre-operative demographic, biochemical, sonographic and cytopathological findings in low-risk thyroid neoplasms.

The present article analyses pre-operative demographic, biochemical, sonographic and histopathological characteristics of low-risk thyroid neoplasms (LRTNs), with a focus on four subgroups, "well-differentiated carcinoma-not otherwise specified" (WDC-NOS), "non-invasive follicular thyroid neoplasm with papillary like nuclear features" (NIFTP), "well-differentiated tumours of uncertain malignant potential" (WDT-UMP) and "follicular tumour of uncertain malignant potential" (FT-UMP). The study retrospectively analyzed the histopathology of 2453 malignant thyroids and the final analyses included 99 cases diagnosed with LRTNs. The demographic and clinical features, pre-operative thyroid function, ultrasonography results, cytopathology results, histopathology results and prognostic classifications were assessed. The groups were similar demographic characteristics and the majority of clinical data, including comorbidities, thyroid function tests, thyroid cancer/neck radiotherapy history. NIFTPs represented 69.7% of all LRTNs. All (100%) WDT-UMPs had solitary nodules. Index nodule volume differed among the groups (p = .036), it was the lowest in WDC-NOS [0.68 (0.63-0.72 cc)] and highest in FT-UMP [12.6 (0.5-64 cc)]. Echogenicity findings were similar. Index nodule TIRADS demonstrated a significant difference (p = .021) but index nodule halo sign and BETHESDA scores were similar in all groups. The diameter, localisation and multicentric structure of LRTNs were again similar for all groups. Finally, prognostic scores suggested similar outcomes in all groups. The majority of LRTNs were NIFTPs in our population and all WDT-UMPs were solitary lesions. Index nodule volume was the most essential discriminating sonographic finding but further research must be performed before discriminatory potential can be described.

Digital analyses of nuclear features can help discriminate among non-invasive follicular thyroid neoplasm with papillary-like nuclear features, papillary thyroid carcinoma follicular subtype, and follicular carcinoma in cytological specimens.

As it stands, the diagnosis of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is primarily based on histological analysis. We hypothesised that computerised analysis of nuclear images of cytological specimens could be used to differentiate NIFTP from papillary thyroid carcinoma follicular subtype (PTCFS) and follicular carcinoma (FC), influencing patient management. We employed a retrospective analytical observational study based on nuclear morphometric variables of cytological material from thyroid nodules classified as PTCFS, NIFTP, or FC. Five cases of each entity were analysed. Cytological slides were photographed, and 1170 cells for each entity were analysed digitally. The captured images were evaluated (blindly) using the ImageJ software package. The morphometric evaluation included area, perimeter, width, height, and circularity. Numerical variables were expressed as mean, median, minimum, and maximum (min; max) values. Kruskal-Wallis and Dunn's tests were used with a 5% significance level. Regarding nuclear analysis, all variables differed among the three groups (p < 0.001). Given the interdependence among the variables, these data indicated that nuclear size was greatest in the NIFTP group, followed by FC and PTCFS. Our analysis of the digital images, with a focus on nuclear parameters, found significantly difference among cytological specimens from cases of NIFTP, PTCFS and FC. Thus, this tool has the potential to provide additional information that may help in the diagnosis of NIFTP, even during the preoperative period. Additional studies are needed to create protocols, evaluate the applicability of nuclear morphological and morphometric parameters-focusing on digital pathology-and create algorithms and tools to assist cytopathologists with their diagnostic routines.

Detailed fine needle aspiration cytopathology findings of noninvasive follicular thyroid neoplasm with papillary-like nuclear features with nuclear grading correlated to that of biopsy and Bethesda category and systematic review.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) poses diagnostic challenge in fine needle aspiration cytopathology (FNAC). We aimed first to document our FNAC Bethesda categories (BCs) for all of our NIFTPs and compare our findings with those in the literature with series containing at least 14 cases each. Cases with final histopathological diagnoses of NIFTP and their preoperative FNAC were retrieved from 2006 to 2022 and our cytopathological BCs were documented. Then the slides were re-reviewed in a blinded manner for detailed classification and the results of both the BCs and blinded reclassification were compared with series in the literature for both BCs and detailed cytopathological review of the cases. Thyroid FNACs of 43 out of 86 patients with final NIFTP diagnoses were obtained. Females composed 72.1% (F/M: 31/12); mean age and mean tumor diameter was 47.6 (19-72 years) and 23.4 mm (7-60 mm), respectively. Totally 81.4% (35/43) were classified in the "indeterminate" diagnostic categories; namely 44.2% (19/43) were reported as atypia of undetermined significance (AUS; BC III), 20.9% (9/43) were follicular neoplasm (FN; BC IV), and 16.3% (7/43) were suspicious for malignancy (SM; BC V). No patient was diagnosed as positive for malignancy (BC VI), preoperatively. Detailed cytomorphologic reevaluation revealed heterogeneous cytopathologic findings and nuclear grade (especially nuclear enlargement, membrane irregularity and elongation) significantly increased with respect to BCs. Systematic review confirmed extremely heterogeneous cytomorphologic nature of NIFTP. NIFTPs were categorized most frequently as AUS, followed by FN and SM on FNAC. Our re-review were not able to specify features solely unique to NIFTP alone but may distinguish these cases from classic papillary thyroid carcinoma.

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.

Diagnostic clues for hyalinizing trabecular tumor on fine needle aspiration cytology.

The hyalinizing trabecular tumor (HTT) is a rare benign neoplasm of the thyroid gland. This neoplasm has overlapping cytological features with Papillary Thyroid Carcinoma, Medullary Carcinoma and Follicular Neoplasm with Nuclear Features of Papillary Carcinoma. This can lead to misdiagnosis of malignancy in fine needle aspiration (FNA) cytology specimens with unnecessary total thyroidectomy. The aim of this study is to determine if there are some cytological features that could help us to suspect HTT on FNA specimens and avoid radical surgery. With this purpose we have collected 6 cases diagnosed of HTT in Hospital Clínico San Carlos of Madrid (Spain) in the last 10 years and reviewed the cytological specimens. We conclude that the presence of hyaline material in FNA specimens of HTT is a constant feature being a diagnostic clue. We must be cautious not to confuse it with dense colloid or amyloid material, the latter seen in Medullary Carcinoma. Papillary architecture and fibrovascular cores are not present in a HTT. Special stains as ki-67, calcitonin and Congo Red staining could help us in achieving the correct diagnosis. We feel the cytopathologists must be aware of the distinguishing features of this lesion, mainly the typical hyaline material to achieve a proper diagnosis and be able to reduce unnecessary aggressive management of these patients.

Ultrasound characteristics of follicular and parafollicular thyroid neoplasms: diagnostic performance of artificial neural network

BackgroundUltrasound is the first-line imaging modality for detection and classification of thyroid nodules. Certain features observable by ultrasound have recently been equated with potential malignancy. This retrospective cohort study was conducted to test the hypothesis that radiomics of the four categorical divisions (medullary [MTC], papillary [PTC], or follicular [FTC] carcinoma and follicular thyroid adenoma [FTA]) demonstrate distinctive sonographic characteristics. Using an artificial neural network model for proof of concept, these sonographic features served as input.MethodsA total of 148 patients were enrolled for study, all with confirmed thyroid pathology in one of the four named categories. Preoperative ultrasound profiles were obtained via standardized protocols. The neural network consisted of seven input neurons; three hidden layers with 50, 250, and 100 neurons, respectively; and one output layer.ResultsRadiomics of contour, structure, and calcifications differed significantly according to nodule type (p = 0.025, p = 0.032, and p = 0.0002, respectively). Levels of accuracy shown by artificial neural network analysis in discriminating among categories ranged from 0.59 to 0.98 (95% confidence interval [CI]: 0.57–0.99), with positive and negative predictive ranges of 0.41–0.99 and 0.78–0.97, respectively.ConclusionsOur data indicate that some MTCs, PTCs, FTCs, and FTAs have distinctive sonographic characteristics. However, a significant overlap of these characteristics may impede an explicit classification. Further prospective investigations involving larger patient and nodule numbers and multicenter access should be pursued to determine if neural networks of this sort are beneficial, helping to classify neoplasms of the thyroid gland.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features: What we have to know

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features: What we have to know

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 2.3cm, 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.

Clinical significance of serum thyroglobulin and tumor volume in delayed surgery for thyroid follicular neoplasms

Clinical significance of serum thyroglobulin and tumor volume in delayed surgery for thyroid follicular neoplasms

Endometrioma Detected on Recombinant TSH-Stimulated 18F-FDG-PET/CT

A 43-year-old female patient diagnosed with high-grade follicular thyroid neoplasm in October 2022, treated with total thyroidectomy + left laterocervical lymphadenectomy in February 2023 with stage T4N0M0. A study with 18F-FDG PET/CT stimulated with Recombinant Thyroid-Stimulating Hormone (rTSH) was requested prior to performing ablative treatment with radioactive iodine (131I) on the same day. Two days prior to the PET/CT study, a subcutaneous injection of rTSH (Thyrogen®) was administered, presenting, immediately after, pain in the right iliac fossa that did not subside with anti-inflammatories. The PET/CT image shows tumor remains in the anterior cervical region and a pelvic mass dependent on the right adnexa, not previously known, of a cystic nature, septated with FDG uptake, with an SUVmax of 15,3, which partially compresses the ipsilateral ureter. Treatment with 131I was postponed due to acute abdominal pain and it was decided to take him to the operating room where an oopherectomy + right adnexectomy was performed with an anatomopathological result of endometrioid cystadenoma. Due to structural similarities and cross-reactivity between hormones, and the presence of TSH receptors in endometrioid tissue, we propose that the growth of the tumor lesion in this case was precipitated by rTSH administration.

Prospects of using the microRNA expression level and parameters of nucleolar organizer regions in the choice of surgical tactics for follicular thyroid tumor of uncertain malignant potential

BACKGROUND: According to modern concepts [1], microRNAs modulate the expression of eukaryotic genes with different oncogenetic directions of action. according to the data from the scientifi literature [2–4], microRNA-146b, -199b can be used for typing thyroid neoplasms, -221, -223, -31, -375, -451a, -551b, etc. Nucleolar organizers (NOR) are sections of chromosomes that form a nucleolus inside the cell nucleus [5–7]. The condition of the regions of nucleolar ribosome organizers (AgNORs) is a marker of the rate of cell proliferation, since they are involved in the regulation of the mitotic cycle [8], and in thyroid pathology [9].AIM: To evaluate the diagnostic significance of the level of expression of some microRNAs and the number of regions of nucleolar organizers in thyroid tissue in the case of follicular thyroid tumor of uncertain malignant potential (FT-UMP) to objectify approaches to the validity of the chosen surgical tactics.MATERIALS AND METHODS: In our study of 3960 patients with surgery due to various thyroidopathies in 2018–2021 on the basis of the thyroid center of Chelyabinsk. 2063 patients were operated on for tumor pathology. In this group, in 98 cases (the study group), FT-UMP was diagnosed based on morphological criteria of neoplasm [10]. This accounted for 4.75% of all surgical tumor pathology during this time. The study group studied the profile, the level of microRNA expression by real-time PCR and the regions of nucleolar organizers in 98 cases of FT-UMP, which amounted to 4.75% of all those operated for thyroid tumors over four years.RESULTS: In 29 (29.6%) cases, a microRNA spectrum characteristic of malignant neoplasms was registered in the tumor tissue. In the remaining 69 (70.4%) cases out of 98 observations, the spectrum and level of microRNA expression corresponded to follicular adenoma. Statistically significant differences in the average number of AgNORs and the ratio between the cell area and the number of AgNORs granules were revealed within the formed subgroups. The study found that an increase in the average number of AgNORs and the ratio of the core area to the number of silver nitrate granules in the 2nd subgroup relative to the 1st, as well as the presence of type II cells indicates the appearance of proliferating tumor cells in the neoplasm and can be considered as prognostic criteria for tumor malignancy. These results are consistent with the obtained indicators of molecular genetic research CONCLUSION: The data can serve as additional criteria for assessing the proliferative activity of the follicular epithelium in thyroid neoplasia. Including clarifying the potential of malignancy. The conditionally malignant variant diagnosed before the operation will justify the need and scope of surgical intervention, and when identifying a set of criteria for conditionally benign HPV, it can be recommended to adhere to wait-and-see tactics.

The histologic outcomes of indeterminate thyroid nodules with rat sarcoma mutations: A case series.

Molecular testing is an adjunct test for thyroid fine needle aspirations with indeterminate diagnoses, with certain mutations showing a greater risk of malignancy (ROM). Rat sarcoma (RAS) point mutations are the most common alterations in indeterminate thyroid nodules. While they can have a high ROM, they are also found in benign disease. This study describes the histologic outcomes of indeterminate nodules with RAS mutations. Bethesda III and IV thyroid nodules with ThyroSeq results showing RAS mutations (NRAS, KRAS, and HRAS) were identified between November 1, 2018 and February 28, 2023. Baseline patient characteristics, ThyroSeq results, and surgical diagnoses were collected. We identified 18 nodules with RAS mutations from 17 patients. Fourteen were NRAS (isolated NRAS in 6; NRAS with other abnormalities [NRAS+] in 8); one was isolated KRAS; and three were HRAS with other abnormalities (HRAS+). NRAS Q16R was the most common amino acid change. Twelve cases had follow-up. Two were malignant, a minimally invasive follicular carcinoma (NRAS+) and a papillary thyroid carcinoma, follicular variant (HRAS+). Three were noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP), 2 HRAS+ and 1 NRAS+. Four were follicular adenomas, one being atypical (3 NRAS+ and one isolated NRAS). One was an oncocytic adenoma (isolated NRAS). Two were nodular hyperplasias (isolated NRAS and NRAS+, respectively). Twenty-eight percent of our RAS-mutated nodules were malignant or NIFTP. All three HRAS-mutated nodules were malignant or NIFTP. The three isolated RAS mutations with follow up were benign (adenomas or nodular hyperplasia). These findings were in line with the literature.

DICER1 Mutations Do Not Always Indicate Dismal Prognosis in Pediatric Poorly Differentiated Thyroid Carcinomas.

Progress in the field of pediatric thyroid pathology has linked DICER1 mutations to benign follicular cell-derived thyroid tumors (e.g., follicular adenoma with papillary architecture, follicular nodular disease), low-risk follicular cell-derived differentiated thyroid carcinomas and PDTCs enriched in fatal or recurrent/progressive disease. The dismal outcome of DICER1-harboring pediatric PDTCs stems from a limited number of reported patients' data given the rarity of pediatric PDTCs. In light of the former observations, the current study assessed clinicopathological variables of a series of 5 pediatric (≤ 18 years old) PDTCs using the Turin criteria (WHO 2022) and also examined the status of DICER1 and TERT promoter mutations. Five PDTCs (3 males, 2 females) were included in the study. The mean age at the time of diagnosis was 15.4 years. No patients had a history of DICER1 syndrome-related tumors or other clinicopathological diagnostic features of DICER1 syndrome. The mean tumor size was 3.9 cm. All tumors were completely submitted for microscopic examination. There was increased mitotic activity ranging from 3 to 10 mitoses per 2 mm2. Tumor necrosis was present in two cases. No PDTC harbored TERT promoter mutation. DICER1 hot spot mutation was identified in one (20%) tumor. The DICER1-mutant tumor had neither associated differentiated thyroid carcinoma component nor other pathological findings in the adjacent thyroid parenchyma. The DICER1-mutant PDTC showed widely invasive growth confined to the thyroid parenchyma. Despite the widely invasive growth, the tumor lacked vascular invasion. Two DICER1 wild-type PDTCs had lymphocytic thyroiditis and another one had underlying follicular nodular disease and/or follicular adenomas. Three DICER1 wild-type PDTCs also had an associated differentiated thyroid carcinoma component with no high-grade features. No abnormal p53 expression (overexpression or global loss) was recorded in all tested tumors. Four patients had follow-up data with a mean follow-up time of 60.25 months (range: 18-86 months). One patient with no evidence of disease recurrence died of anunrelated cause after 18 months of the initial surgery, all remaining patients were alive with no distant metastasis at their last visit. Of the 4 patients with lymph node (LN) dissection, one DICER1 wild-type PDTC had recurrent nodal disease. During the follow-up period (72 months), no local recurrence or distant metastases was detected in the DICER1-mutant PDTC. Taken together all reported findings from earlier series, DICER1 mutations alone may not necessarily indicate dismal outcome in a subset of pediatric PDTCs. The occurrence of additional genomic alterations as discussed in some earlier reports may be contributing to tumor progression or aggressivity of pediatric PDTCs. The lack of vascular invasion in the current DICER1-mutant pediatric PDTC may also explain an indolent biologic outcome. The risk escalation of DICER1 mutations should integrate the status of additional genetic events and well-established pathologic variables in order to ensure predictive dynamic risk stratification in DICER1-mutant pediatric PDTCs. Additional studiesare needed to corroborate the findings of this study and advance our knowledge in pediatric thyroid neoplasia.

Classification of Thyroid Tumors Based on DNA Methylation Patterns.

Background: Alterations in DNA methylation are stable epigenetic events that can serve as clinical biomarkers. The aim of this study was to analyze methylation patterns among various follicular cell-derived thyroid neoplasms to identify disease subtypes and help understand and classify thyroid tumors. Methods: We employed an unsupervised machine learning method for class discovery to search for distinct methylation patterns among various thyroid neoplasms. Our algorithm was not provided with any clinical or pathological information, relying exclusively on DNA methylation data to classify samples. We analyzed 810 thyroid samples (n = 256 for discovery and n = 554 for validation), including benign and malignant tumors, as well as normal thyroid tissue. Results: Our unsupervised algorithm identified that samples could be classified into three subtypes based solely on their methylation profile. These methylation subtypes were strongly associated with histological diagnosis (p < 0.001) and were therefore named normal-like, follicular-like, and papillary thyroid carcinoma (PTC)-like. Follicular adenomas, follicular carcinomas, oncocytic adenomas, and oncocytic carcinomas clustered together forming the follicular-like methylation subtype. Conversely, classic papillary thyroid carcinomas (cPTC) and tall cell PTC clustered together forming the PTC-like subtype. These methylation subtypes were also strongly associated with genomic drivers: 98.7% BRAFV600E-driven cancers were PTC like, whereas 96.0% RAS-driven cancers had a follicular-like methylation pattern. Interestingly, unlike other diagnoses, follicular variant PTC (FVPTC) samples were split into two methylation clusters (follicular like and PTC like), indicating a heterogeneous group likely to be formed by two distinct diseases. FVPTC samples with a follicular-like methylation pattern were enriched for RAS mutations (36.4% vs. 8.0%; p < 0.001), whereas FVPTC- with PTC-like methylation patterns were enriched for BRAFV600E mutations (52.0% vs. 0%, Fisher exact p = 0.004) and RET fusions (16.0% vs. 0%, Fisher exact p = 0.003). Conclusions: Our data provide novel insights into the epigenetic alterations of thyroid tumors. Since our classification method relies on a fully unsupervised machine learning approach for subtype discovery, our results offer a robust background to support the classification of thyroid neoplasms based on methylation patterns.

Three-dimensional nuclear architecture distinguishes thyroid cancer histotypes.

Molecular markers can serve as diagnostic tools to support pathological analysis in thyroid neoplasms. However, because the same markers can be observed in some benign thyroid lesions, additional approaches are necessary to differentiate thyroid tumor subtypes, prevent overtreatment and tailor specific clinical management. This applies particularly to the recently described variant of thyroid cancer referred to as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). This variant has an estimated prevalence of 4.4% to 9.1% of all papillary thyroid carcinomas worldwide. We studied 60 thyroid lesions: 20 classical papillary thyroid carcinoma (CPTC), 20 follicular variant of PTC (FVPTC) and 20 NIFTP. We examined morphological and molecular features to identify parameters that can differentiate NIFTP from the other PTC subtypes. When blindly investigating the nuclear architecture of thyroid neoplasms, we observed that NIFTP has significantly longer telomeres than CPTC and FVPTC. Super-resolved 3D-structured illumination microscopy demonstrated that NIFTP is heterogeneous and that its nuclei contain more densely packed DNA and smaller interchromatin spaces than CPTC and FVPTC, a pattern that resembles normal thyroid tissue. These data are consistent with the observed indolent biological behavior and favorable prognosis associated with NIFTP, which lacks BRAFV600E mutations. Of note, next-generation thyroid oncopanel sequencing was unable to distinguish the thyroid cancer histotypes in our study cohort. In summary, our data suggest that 3D nuclear architecture can be a powerful analytical tool to diagnose and guide clinical management of NIFTP.

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

NIFT-P (non-invasive follicular thyroid neoplasm with papillary-like nuclear features) is an encapsulated follicular variant of papillary thyroid carcinoma (PTC) with non-aggressive 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, few information is available about its ability in identifying NIFT-P. 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. We retrospectively evaluated 403 consecutive patients submitted to thyroid surgery, with positive histology for at least one nodule being NIFT-P, follicular variant of PTC (FV-PTC), follicular thyroid carcinoma (FTC) or follicular adenoma (FA). The US features of NIFT-P (n=116), FV-PTC (n=170), FTC (n=76) and FA (n=90) were reported. FV-PTC and FTC more frequently showed irregular margins, presence of calcifications, "taller than wide" shape, and the absence of halo compared to NIFT-P. Furthermore, FTC but 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 to FV-PTC and FTC. US features of NIFT-P are frequently superimposable to those of nodules with low-suspicious of malignancy. NIFT-P is almost never classified in the high-suspicious category according to the main US RSS. Therefore, although the pre-operative 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.