Follicular Variant Of Papillary Thyroid Carcinoma Research Articles

Abstract C012: Exploring thrombospondin-1 variant and splicing factors as potential diagnostic biomarkers and therapeutic targets in thyroid cancer

Abstract Thyroid cancer is the most common type of cancer affecting the thyroid gland, accounting for 11.8% of all cancer cases in Korea as of 2020. The majority of thyroid cancer cases belong to the papillary thyroid cancer (PTC) subtype. Diagnostic methods for thyroid cancer include blood tests, ultrasound examinations, fine needle aspiration cytology (FNAC), PET/CT scans, and others. However, distinguishing between different subtypes of thyroid cancer, such as follicular variant of papillary thyroid carcinoma (FVPTC), follicular adenoma (FA), and follicular thyroid carcinoma (FTC), remains challenging, often leading to unnecessary surgeries for patients. In this study, antibody arrays were used to analyze tumor and adjacent normal tissues from thyroid cancer patients. Thrombospondin 1 (TSP1), was found to be more highly expressed in tumor tissue compared to normal tissue. TSP1 is a glycoprotein with diverse biological functions that can either inhibit or promote tumorigenesis depending on the context. The researchers discovered a transcriptional variant of TSP1 (TSP1V) generated by intron retention (IR), which was more highly expressed in normal tissue compared to tumor tissue. Overexpression of TSP1V in thyroid cancer cells resulted in the secretion of the protein into the medium or its deposition in the extracellular matrix (ECM). TSP1V exhibited anti-cancer properties, inhibiting proliferation, migration, invasion, colony formation, and spheroid formation of thyroid cancer cells in vitro. It also suppressed tumor growth in a mouse experiment. The researchers explored the TGF-β pathway, a well-known signaling pathway associated with TSP1, and found that TSP1V inhibited the phosphorylation of Smad2 and FAK, unlike TSP1 wild-type (TSP1W). To investigate the mechanism behind TSP1V's generation through IR, we examined splicing factors. RBM5 overexpression inhibited IR induced by anti-cancer compounds, while RBM5 knockdown increased IR. Sulindac sulfide, one of the compounds tested, increased IR by inhibiting the phosphorylation of RBM5. Additionally, trans-chalcone was found to increase IR by demethylating DNA. Trans-chalcone also reduced the expression of TSP1W, DNMT3b, and MeCP2 in a time-dependent manner. The study concluded by analyzing tumor and adjacent normal tissues from patients with follicular neoplasm (FN), including benign thyroid nodule (BTN) and differentiated thyroid carcinoma (DTC). We also observed significant differences in the ratio of TSP1V to TSP1W. These findings provide evidence that secreted proteins like TSP1 have the potential to serve as diagnostic biomarkers and therapeutic targets for thyroid cancer. Moreover, the study enhances our understanding of the molecular mechanisms underlying the anti-cancer activities of these proteins. Citation Format: Yukyung Hong, Ilju Kim, Hyunjin Moon, Jaehak Lee, Pattawika Lertpatipanpong, Chang Hwan Ryu, Junsun Ryu, Seung Joon Baek. Exploring thrombospondin-1 variant and splicing factors as potential diagnostic biomarkers and therapeutic targets in thyroid cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C012.

Clinical Outcomes of Radioactive Iodine Redifferentiation Therapy in Previously Iodine Refractory Differentiated Thyroid Cancers.

Objective: Redifferentiation therapy (RDT) can restore radioactive iodine (RAI) uptake in differentiated thyroid cancer (DTC) cells to enable salvage 131I therapy for previously RAI refractory (RAIR) disease. This study evaluated the clinical outcomes of patients who underwent RDT and identified clinicopathologic characteristics predictive of RAI restoration following RDT. Methods: This is a retrospective case series of 33 patients with response evaluation criteria in solid tumors (RECIST)-progressive metastatic RAIR-DTC who underwent RDT between 2017 and 2022 at the Mayo Clinic (Rochester, MN). All patients underwent genomic profiling and received MEK, RET or ALK inhibitors alone, or combination BRAF-MEK inhibitors for 4 weeks. At week 3, those with increased RAI avidity in metastatic foci received high-dose 131I therapy. Baseline and clinicopathologic outcomes were comprehensively reviewed. Results: Of the 33 patients, 57.6% had restored RAI uptake following RDT (Redifferentiated subgroup). 42.1% (8/19) with papillary thyroid cancers (PTC), 100% (4/4) with invasive encapsulated follicular variant PTCs (IEFV-PTCs), and 100% (7/7) with follicular thyroid cancers (FTC) redifferentiated. All (11/11) RAS mutant tumors redifferentiated compared with 38.9% (7/18) with BRAF mutant disease (6 PTC and 1 IEFV-PTC). 76.5% (13/17) of redifferentiated and 66.7% (8/12) of non-redifferentiated patients achieved a best overall RECIST response of stable disease (SD) or non-complete response/non-progressive disease. Both subgroups had a median 12% tumor shrinkage at 3 weeks on drug(s) alone. The redifferentiated subgroup, following high-dose 131I therapy, achieved an additional median 20% tumor reduction at 6 months after RDT. There were no statistically significant differences between both groups in progression free survival (PFS), time to initiation of systemic therapy, and time to any additional therapy. Of the entire cohort, 6.1% (2/33) experienced histologic transformation to anaplastic thyroid cancer, 15.1% (5/33) died, and all had redifferentiated following RDT and received 131I therapy. Conclusion: RDT has the potential to restore RAI avidity and induce RECIST responses following 131I therapy in select patients with RAIR-DTC, particularly those with RAS-driven "follicular" phenotypes. In patients with PTC, none of the evaluated clinical outcomes differed statistically between the redifferentiated and non-redifferentiated subgroups. Further studies are needed to better characterize the long-term survival and/or safety outcomes of high-dose RAI following RDT, particularly whether it could be associated with histologic anaplastic transformation.

Comparison of Treatment and Prognosis Between Follicular Variant Papillary Thyroid Carcinoma and Classical Papillary Thyroid Carcinoma.

This cohort study evaluated the associations of different treatments with the prognosis of follicular variant papillary thyroid carcinoma (FVPTC) and classical papillary thyroid carcinoma (CPTC) patients. The data of 69034 PTC patients were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. The 5-year mortality of CPTC and FVPTC patients receiving surgery, radiation and combination therapy were compared. The univariable and multivariable cox proportional risk models explored the associations between different treatments and the 5-year mortality in CPTC and FVPTC patients. The 5-year mortality of CPTC patients was 2.81% and FVPTC patients was 2.47%. Compared with CPTC receiving lobectomy and/or isthmectomy, those not receiving surgery were associated with increased risk of 5-year mortality [Hazards ratio (HR)=3.27, 95% confidence interval (CI): 2.55-4.20] while total thyroidectomy was correlated with reduced risk of 5-year mortality (HR=0.67, 95%CI: 0.55-0.80). Radioactive iodine (RAI) was linked with decreased risk of 5-year mortality in CPTC patients (HR=0.57, 95%CI: 0.50-0.65). CPTC patients undergoing both surgery and radiation were related to decreased risk of 5-year mortality compared with those receiving surgery only (HR=0.55, 95%CI: 0.48-0.63). CPTC patients receiving neither surgery nor radiation (HR=4.53, 95%CI: 3.72-5.51) or those receiving radiation (HR=1.98, 95%CI: 1.13-3.48) were correlated with elevated risk of 5-year mortality. The elevated risk of 5-year mortality in FVPTC patients was reduced in those undergoing RAI (HR=0.63, 95%CI: 0.51-0.76). In conclusion, combination therapy was associated with decreased risk of 5-year mortality in CPTC and FVPTC patients, which might provide a reference for the management of these patients.

SAT520 Efficacy of Radioactive Iodine Redifferentiation Therapy in Previously Iodine Refractory Differentiated Thyroid Cancers

Abstract Disclosure: D. Toro-Tobon: None. J.C. Morris: None. C. Hilger: None. C.S. Peskey: None. D.M. Jolanta: None. M.M. Ryder: None. Objective: Patients with metastatic differentiated thyroid cancer (DTC) that are radioactive iodine (RAI) refractory (RAIR) have a poor prognosis. Redifferentiation therapy (RDT) has emerged as a potential approach to restore RAI avidity in this disease. The aim of this study was to examine the efficacy and predictors of RAI restoration in RAIR disease, as well as examine the outcomes of patients re-treated with high dose RAI following RDT. Methods: A retrospective review was conducted of 33 patients with RECIST-progressive metastatic RAIR-DTC who underwent RDT between 2017 and 2022 at the Mayo Clinic. All patients underwent genomic profiling, and either MEK inhibitor alone or combination BRAF-MEK inhibitors were prescribed for 4 weeks. At week 3, Thyrogen-stimulated I-123 whole body scans were performed. Those with increased RAI avidity in metastatic foci received high dose I-131 therapy using a previously published modified dosimetry protocol. Baseline and clinicopathologic outcomes were comprehensively reviewed. Results: Of the 33 patients, 12 of 23 (52%) with papillary thyroid cancers (PTC), 4 of 4 (100%) with follicular variant PTCs (FV-PTC), and 7 of 7 (100%) with follicular thyroid cancers (FTC) had restored RAI avidity following RDT using dabrafenib/trametinib (7 for BRAF mutant disease) or trametinib monotherapy (12 for RAS mutant disease). All 11 (100%) RAS mutant tumors (2 PTC, 3 FV-PTC, and 6 FTC) had RAI avidity restoration compared to 7 (36%) with BRAF mutant disease (6 PTC, and 1 FV-PTC). Of the 19 patients (57%) with restored RAI avidity (responders), 18 (94%) received I-131 with a median dose of 294 mCi. The median thyroglobulin (Tg) in responders was 294 mIU/L as compared to 29 mIU/L in non-responders. Following RDT-facilitated I-131 treatment, 94.7% achieved RECIST defined objective response (complete or partial response, stable disease, non-complete response/non-progressive disease) with a median progression free survival of 18 months and an overall survival of 30 months. Overall, patients with FTC (p=0.01), RAS mutation (p<0.001), Tg of 294 mIU/L or more (p=0.03), largest tumor diameter of 1.7 cm or less (p=0.05), bone metastasis (p=0.007), and without locoregional nodal disease (p=0.04), were more likely to demonstrate restored RAI avidity following RDT. Of the entire cohort, 2 (6%) patients experienced histologic transformation to anaplastic thyroid cancer and 5 (15%) patients died, all had had RAI restoration and received high-dose RAI following RDT. Conclusion: RDT has the potential to restore RAI avidity and induce RECIST responses following I-131 therapy in select patients with RAIR-DTC, particularly those with RAS mutations and ‘follicular’ phenotypes. Further studies are needed to better characterize the long-term survival and/or safety outcomes of high-dose RAI following RDT, particularly whether it could be associated with histologic transformation. Presentation Date: Saturday, June 17, 2023

THU224 Is Chronic Lymphocytic Thyroiditis Associated With Aggressive Differentiated Thyroid Cancer In A Predominantly Hispanic Pediatric Population?

Abstract Disclosure: N. Solano: None. D. Baboun: None. A. Martinez-Sanchez: None. A. Diaz: None. A. Carrillo-Iregui: None. F. Alkhoury: None. Background: The risk of developing papillary thyroid carcinoma (PTC) appears to be increased among patients with chronic lymphocytic thyroiditis (CLT). Studies in adults have shown that the presence of CLT is associated with less aggressive PTC; however, this correlation is unclear in pediatric patients. Objective: The purpose of this study is to determine a possible correlation between CLT and markers of aggression severity using histopathological findings, tumor size, and lymph node involvement among patients with differentiated thyroid carcinoma (DTC) in a free-standing children’s hospital with a predominantly Hispanic population. Methods: Upon Institutional Review Board approval, we performed a retrospective chart review from 2012-2022 of 55 patients with a final diagnosis of DTC. We analyzed the correlation between CLT and histopathological findings. Statistical analysis was performed by using t-tests and chi-squared tests. Results: The patients reviewed were between 8-20 years of age. Forty-nine (89.1%) patients identified as Hispanic, and 41 (74.6%) were females. Twenty-five (45.5%) patients had a diagnosis of CLT; 19 (76.0%) of these patients had classic PTC, 3 (12.0%) had the follicular variant of PTC, and 3 (12.00%) had another variant of PTC. Of the 30 (54.5%) patients who did not have CLT, 13 (43.3%) had the classic variant of PTC, 10 (33.3%) had the follicular variant of PTC, and 7 (23.3%) had another variant of PTC. The distribution of the histopathological findings was significant (p=.048). Patients with CLT had significantly smaller tumor sizes (1.8 vs. 2.5 cm, respectively [p=.048]). Of the 36 patients with lymph node involvement, 20 (55.6%) had CLT. Of the 19 patients without lymph node involvement, 5 (26.3%) had CLT. The association between the presence of CLT and lymph node involvement was significant (p=.038). Conclusions: In our population, patients with CLT had a significantly higher presence of the classic variant of PTC. Studies in adults have shown a tendency of these lesions to have a higher risk of disease than those with the follicular variant. Patients with CLT had a smaller tumor size, likely as a result of earlier detection of thyroid nodules due to frequent clinical evaluations and thyroid ultrasounds. However, patients with CLT tended to have a higher frequency of lymph node involvement. More studies with pediatric populations are needed to clarify the possible association between CLT and DTC. Presentation: Thursday, June 15, 2023

SAT535 ANKRD26-RET Fusion Positive Metastatic Papillary Thyroid Carcinoma - Advanced Presentation of a Rare Mutation

Abstract Disclosure: H. Hashmi: None. A. Ankireddypalli: None. L. Burmeister: None. A. Nelson: None. K. Amin: None. Background: While rearranged during transfection (RET) protooncogene mutations have been commonly associated with thyroid malignancy, ankyrin repeat domain containing protein 26 (ANKRD26) has been primarily linked to hematologic malignancy. Exon 29 of ANKRD26 (Chromosome [Chr] 10p12.1) has been shown to fuse with exon 12 of RET (Chr 10q11.21), resulting in a genetic fusion mutation ANKRD26:RET. This is a rare genetic mutation in papillary thyroid cancer with only one previously reported case. We report the first case in the US of this novel genetic mutation with a unique clinical presentation. Clinical Presentation: A 48-year-old, male patient presented with lower back pain radiating to the lower extremities of one year duration. MRI lumbar spine revealed an irregular mass lesion in the L1 vertebral body with extraosseous soft tissue extension, L1 compression fracture and extension into the T12 body. CT CAP revealed a 4.8 x 3.6 cm, heterogenous right thyroid lobe with tracheal compression and sub centimeter pulmonary nodules in the left lower and right middle lobes. Biopsy of the L1 paravertebral mass was diagnostic for metastatic thyroid carcinoma of a follicular pattern. Molecular testing with a next generation sequencing fusion profile assay was positive for ANKRD26:RET gene rearrangement. Thyroid ultrasound was notable for a solid, hypoechoic, 3.2 x 3.1 x 2.9 cm right lobe nodule with echogenic foci and level 4 lymph nodes with loss of reniform shape and fatty hilum. FNA of the nodule and right level 4 lymph node was suspicious for follicular neoplasm. The patient was admitted for acute cord compression necessitating extensive laminectomy, vertebral reconstruction and resection of the L1 paraspinal tumor. Pathology was positive for metastatic, follicular variant, papillary thyroid carcinoma. Total thyroidectomy, central and right modified radical neck dissection was performed. Pathology demonstrated a 4.2 cm papillary carcinoma, follicular type with tall cell variant; confined to the thyroid. Extensive angioinvasion (≥ 4 vessels) and lymphatic invasion was present. 10/32 positive lymph nodes. TNM grading was T3aN1bM1. Summary: The only other case of ANKRD26-RET fusion positive papillary thyroid cancer in the literature was reported by Staubitz et al in Germany in 2019. They reported a case of a 78-year-old male with follicular variant papillary thyroid carcinoma (pT3,pN0,M0). To our knowledge, our case is the second worldwide and the first to be reported in the United States of this rare fusion protein positive thyroid cancer. Such an aggressive presentation with distant osseous metastases has to our knowledge not been previously described. Conclusion: The clinical and therapeutic implications of this rare genetic mutation are not currently well elucidated. We present this case with the intent to expand the existing literature and increase recognition of this rare genetic mutation. Presentation Date: Saturday, June 17, 2023

SAT553 A Case of Metastatic Functional Papillary Thyroid Cancer in the Setting of Graves’ Disease

Abstract Disclosure: N. Manuel: None. S.J. Sternlieb: None. J. Dendy: None. Q.Z. Iqbal: None. A Case of Metastatic Functional Papillary Thyroid Cancer In the Setting of Graves’ DiseaseManuel, N., Sternlieb, S., Grissett, B., Iqbal, Q., Dendy, J. Background: Grave’s disease (GD) and papillary thyroid cancer (PTC) can be concomitant diseases. We report a rare case of metastatic PTC with concomitant GD leading to symptomatic hyperthyroidism despite total thyroidectomy. Clinical Case: A 58-year-old woman with longstanding history of thyroid nodules and left dominant nodule with benign biopsy on multiple occasions presented to her PCP with dyspnea, weight loss and globus sensation. CT of the chest was obtained revealing tracheal deviation from neck mass, mediastinal lymphadenopathy and multiple pulmonary nodules. Biopsy of lung nodule showed follicular features consistent with tumor cells of thyroid origin. She had a total thyroidectomy with central neck dissection with a final diagnosis of left sided 5 cm infiltrative follicular variant papillary thyroid carcinoma. Thyroid hormone replacement was initiated and on follow up 4 weeks later she was noted to be tachycardic at weight-based dose. At that time TSH was <0.010 uIU/mL (0.400 - 4.00), free T4 was 1.96 ng/dL (0.71 – 1.51) and Thyroglobulin was found to be 31516 ng/dL (Athyrotic <0.1). Prior to planned RAI she developed symptoms of dyspnea on exertion and edema and was sent to the ER for abnormal D. Dimer. Workup for PE was negative including CTA of the chest. A follow up visit showed further symptoms of hyperthyroidism with worsening fatigue, dyspnea, palpitations and new onset tremor. Levothyroxine dose was decreased further but 2 weeks later she returned to the ER with worsened thyroid function tests, and she was admitted for symptomatic hyperthyroidism. Levothyroxine was held and she was placed on PTU and propranolol. Given the overt symptomatic hyperthyroidism there were concerns for either Jod-Basedow phenomenon from iodine load with recent imaging or for hyperfunctioning PTC metastasis as the cause. Thyrotropin receptor antibody level was checked to further clarify and was elevated at 22 IU/L (0.00 – 1.75) consistent with GD. An I-131 diagnostic whole-body scan demonstrated small foci of right thyroid bed remnant and iodine-avid metastases involving mediastinal nodal disease as well as pulmonary and osseous metastases. She then underwent RAI therapy with 104.5 mCi I-131 without Thyrogen stimulation. Follow up whole body scan showed persistence of iodine-avid metastasis without any new foci of uptake compared to pretreatment scans. Conclusion: Although the coexistence of them is rare, GD should be put into the differential of rapidly progressive metastatic PTC especially if patient markedly hyperthyroid on lower doses of thyroid hormone. While functional thyroid carcinoma is rare, with less than 100 cases in literature, thorough investigation should be completed in order to not miss this concomitant disease process. Presentation Date: Saturday, June 17, 2023

SAT508 Siblings With Heterozygous DICER1 c.322C>T, pGln108* Variant: A Novel Genetic Variant for DICER1 Syndrome

Abstract Disclosure: N.L. Yamashita: None. J. Austin: Consulting Fee; Self; Ascendis, Vertice. Research Investigator; Self; IBSA Pharmaceuticals. Background: Several genetic variants are implicated in DICER1 syndrome - a neoplasm predisposition syndrome with a spectrum of presentations with both benign and malignant tumors. DICER1 c.322C>T, pGln108* variant is a new mutation that was found in this case of two siblings presenting with thyroid cancers. Clinical case: Sibling A is a 10-year-old female who presented to the emergency department (ED) with a rapidly progressing right neck mass. She underwent fine needle aspiration (FNA) that returned as Follicular Lesion of Undetermined Significance (FLUS), Bethesda III. Subsequently, she had a right lobectomy, and pathology results revealed multiple follicular adenomatous nodules with focal papillary hyperplasia. Approximately one year later, she re-presented with a new left sided neck swelling with ultrasound revealing three new nodules. She underwent left lobectomy and pathology showed follicular variant papillary thyroid carcinoma (FVPTC). She was started on levothyroxine replacement daily. Her surveillance regimen included I-123 thyroid uptake scans which showed uptake in the neck. Her TSH-stimulated thyroglobulin was as high as 4.3 ng/mL with negative thyroglobulin antibody titer. She did not receive radioactive iodine ablation (RAI). Since then, routine thyroglobulin levels have remained low and neck ultrasounds have been reassuring. She is currently 19 years old. Approximately three years after Sibling A’s second lobectomy, her sister, Sibling B, presented as an 11-year-old female to the ED with neck swelling. Thyroid ultrasound showed multiple solid and cystic nodules on both right and left thyroid lobes. FNA returned with Bethesda Category IV (suspicious for follicular neoplasm) on the left lower nodule and Bethesda II (benign follicular nodule) on other nodules. She underwent total thyroidectomy and was found to have follicular thyroid carcinoma (FTC). TSH-stimulated thyroglobulin was as high as 8.9 ng/mL. Her surveillance thyroid scan showed uptake in the right thyroidectomy bed and 1.6 cm nodule was found on ultrasound. FNA of this lesion was benign with stable repeat thyroid scans with downtrending TSH-stimulated thyroglobulin. This patient is currently 15 years old. Soon after the Sibling B was diagnosed with FTC, the decision was made to pursue genetic analysis. Both siblings underwent mutation analysis which were both positive for heterozygous DICER1 c.322C>T, pGln108* variant.Conclusion: This case introduces a novel variant to DICER1 syndrome: DICER1 c.322C>T, pGln108* variant. Without a family history of multinodular goiter (MNG), thyroid cancers, or other associated tumors to this syndrome, these siblings had unusual presentations of a germline DICER1 syndrome variant. This case highlights the expressive variability in DICER1 syndrome and this variant may be of consideration when children present without other predisposing tumors. Presentation Date: Saturday, June 17, 2023

THU673 Unusual Metastasis Of Differentiated Thyroid Carcinoma

Abstract Disclosure: M. Aiad: None. O.A. Aluko: None. B. Bhatt: None. Background: Papillary thyroid cancer (PTC) is the most common form of differentiated thyroid malignancy. Distant metastasis of PTC are rare and usually occur in the bones, lungs, and lymph nodes of the neck. Retinal and skin metastases are extremely rare. We present a case of PTC with metastasis to the distal extremity with sites including retina, skin and breasts. Clinical Case: A 40-year-old Caucasian female with a past medical history of papillary thyroid cancer at age 16 status post total thyroidectomy followed by two radioactive iodine treatments, who is incidentally found to have recurrent metastatic disease to lungs, retina, subcutaneous soft tissue and bones. After having an accident, trauma CT revealed pulmonary nodules and around the time patient started to notice subcutaneous lumps on the chest and gradually worsening blurry vision indicating further imaging as well as ophthalmological evaluation. The biopsy of the right lower lung nodules showed metastatic differentiated follicular variant papillary thyroid cancer, positive for RET mutation. TSH was appropriately suppressed at 0.128uIU/mL on levothyroxine 100 mcg daily, with elevated thyroglobulin level 47ng/mL and antibody 1.7IU/mL. The molecular testing was positive for RET gene mutation; thus she started targeted therapy with selpercatinib 120 mg twice daily. Shortly after starting therapy, she presented to the ER with complaints of headaches and refractory nausea. Imaging done showed evidence of intracranial metastases, bilateral intraocular lesions in the posterior globe as well as intraventricular hemorrhage. She received IV steroids, selpercatinib was held due to the possibility of exacerbating intraventricular hemorrhage. Following multidisciplinary discussion between neuro-oncology and radiation oncology, she started stereotactic radiotherapy (SRT) to choroidal plexus lesions with a plan to restart systemic therapy once SRT is completed. Conclusion: The epidemiological aspects of thyroid metastases in rare sites are likely unknown and could significantly impact patient management. Most cases of uncommon metastasis have been reported after several years of diagnosis such as in our patient who developed multiple metastasis to rare sites including skin, retina, breast and choroid plexus. Presentation: Thursday, June 15, 2023

Subcentimetric papillary thyroid carcinoma with extensive lymph node and brain metastasis: case report and review of literature.

We report a 61-year-old male patient without personal history of thyroid carcinoma or radiation exposure. In 2011, he presented with a cervical mass whose biopsy diagnosed a papillary thyroid carcinoma (PTC) in a lymph node metastasis (LNM). Total thyroidectomy with lymphadenectomy of central and ipsilateral compartment was performed. Histopathology identified a 2 mm follicular variant of PTC and LNM in 25/25 lymph nodes. The patient was treated with 150 mCi of radioactive iodine (RAI), followed by levothyroxine suppressive therapy. In 2016, a retrotracheal mass was diagnosed, suggesting local recurrence; patient was submitted to surgical excision and RAI therapy (120 mCi). Due to seizures, in 2019, a brain CT was performed that diagnosed brain metastases. The patient underwent debulking of the main lesion. Histopathology analysis confirmed a metastatic lesion with variated morphology: classical PTC and follicular pattern and hobnail and tall cell features. Molecular analysis revealed BRAFV600E in LNM at presentation and BRAFV600E and TERT promoter (TERTp) mutations in the recurrent LNM and brain metastasis. Based upon this experience we review the reported cases of subcentimetric PTC with brain metastases and discuss the molecular progression of the present case. Papillary microcarcinoma (PMCs) usually have very good prognosis with low impact on patient survival. PMCs presenting in elderly patients with LNM at diagnosis may carry a guarded outcome. Brain metastasis although rare indicate aggressive phenotypic features. Patient risk stratification of PMCs based on histopathological analysis and genetic testing may have a significant impact on prognosis providing therapeutic markers, that may predict disease progression and overall outcome.

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.

A Comparative Analysis of NOX4 Protein Expression in Malignant and Non-Malignant Thyroid Tumors.

The comparative analysis of the expression of the reactive oxygen species-generating NADPH oxidase NOX4 from TCGA data shows that the NOX4 transcript is upregulated in papillary thyroid carcinomas (PTC)-BRAFV600E tumors compared to PTC-BRAFwt tumors. However, a comparative analysis of NOX4 at the protein level in malignant and non-malignant tumors is missing. We explored NOX4 protein expression by immunohistochemistry staining in malignant tumors (28 classical forms of PTC (C-PTC), 17 follicular variants of PTC (F-PTC), and three anaplastic thyroid carcinomas (ATCs)) and in non-malignant tumors (six lymphocytic thyroiditis, four Graves' disease, ten goiters, and 20 hyperplasias). We detected the BRAFV600E mutation by Sanger sequencing and digital droplet PCR. The results show that NOX4 was found to be higher (score ≥ 2) in C-PTC (92.9%) compared to F-PTC (52.9%) and ATC (33.3%) concerning malignant tumors. Interestingly, all C-PTC-BRAFV600E expressed a high score for NOX4 at the protein level, strengthening the positive correlation between the BRAFV600E mutation and NOX4 expression. In addition, independent of the mutational status of BRAF, we observed that 90% of C-PTC infiltrating tumors showed high NOX4 expression, suggesting that NOX4 may be considered a complementary biomarker in PTC aggressiveness. Interestingly, NOX4 was highly expressed in non-malignant thyroid diseases with different subcellular localizations.

Probability of malignancy and molecular alterations as determined by ThyroSeq v3 genomic classifier in Bethesda Category IV.

ThyroSeq molecular testing assesses the probability of malignancy (POM) in thyroid fine-needle aspiration cytology (FNAC) with indeterminate cytology. The aim was to investigatewhether Bethesda category IV (BIV) subcategories are associated with specific molecular alterations, molecular-derived risk of malignancy (MDROM), and risk of malignancy (ROM). FNAC slides, associated ThyroSeq, version 3, Genomic Classifier results, and surgical follow-up were retrieved for BIV nodules. Nodules were subcategorized as follicular neoplasm (FN) with or without cytologic atypia or oncocytic follicular neoplasm (OFN). The MDROM, ROM, and frequency of molecular alterations in FN and OFN were analyzed. p < .05 was considered significant. A total of 92 FNAC were identified and subcategorized into 46 FN (15 with and 31 without cytologic atypia) and 46 OFN. The benign call rate and the positive call rate were 49% and 51%, respectively. The MDROM in BIV was 34.3%, trending lower in OFN than in FN. RAS mutations were significantly more frequent in FN when compared to OFN (p = .02). Chromosomal copy number alterationswere more often present in OFN than in FN (p < .01). On histologic follow-up, ROM in OFN was trending lower than in FN (p = .1). The most common diagnosis in OFN was oncocytic adenoma, whereas follicular variant papillary thyroid carcinoma was most common in FN. The MDROM and ROM were trending lower in OFN compared with FN, and the molecular alterations differed between OFN and FN subcategories.

Molecular and clinical features of papillary thyroid cancer in adult patients with a non-classical phenotype.

Genotyping is fundamental in papillary thyroid cancer (PTC) and helps to enhance diagnosis and prognosis and determine appropriate treatments. The phenotype-genotype association in PTC was previously studied, with BRAF V600E characterizing classic PTC and tall-cell PTC and RAS mutations characterizing follicular-variant PTC. In clinic, some non-classical histological subtypes of PTC were also identified, however, their genotype remains unclear. In this study, we collected samples of these non-classical PTC after the exclusion of classic phenotypes and examined their phenotypes, genotype and the relationship between phenotype and genotype. We screened out non-classical PTC by excluding classical PTC from 1,059 different thyroid samples, and a total of 24 cases was obtained and described from the morphological features, which is rare in differentiated PTC. DNA/RNA sequencing was performed using 18 available samples to describe the genetic features. PTC with the non-classical phenotype were characterized cuboidal to low columnar tumor cells with subtle nuclear features of PTC and without discernible nuclear elongation, concurrently with dense microfollicles, delicate papillae or solid nodules with delicate fibrovascular cores. They were associated with lymphatic vessel invasion (P<0.001) but not with a worse prognosis (P=0.791). Gene fusions were identified in 14 of 18 (77.8%) cases, including eight fusions of NTRK and six fusions of RET. The high percentage of fusions in this papillary thyroid cancer subgroup suggested a correlation of gene fusions with the phenotype that does not belong to the BRAF V600E-mutant or RAS-mutant group. Our study retrospectively screened a large cohort of different thyroid tissue samples, and presented the histopathological and genetic features of a non-classical phenotype of PTC from 24 patients. It may contribute to diagnose in PTC, and patients of these non-classical phenotype may benefit from targeted therapy, compared to a natural patient cohort without selection.

DICER1 RNase IIIb domain mutations trigger widespread miRNA dysregulation and MAPK activation in pediatric thyroid cancer.

DICER1 is a highly conserved RNase III endoribonuclease essential for the biogenesis of single-stranded mature microRNAs (miRNAs) from stem-loop precursor miRNAs. Somatic mutations in the RNase IIIb domain of DICER1 impair its ability to generate mature 5p miRNAs and are believed to drive tumorigenesis in DICER1 syndrome-associated and sporadic thyroid tumors. However, the DICER1-driven specific changes in miRNAs and resulting changes in gene expression are poorly understood in thyroid tissue. In this study, we profiled the miRNA (n=2,083) and mRNA (n=2,559) transcriptomes of 20 non-neoplastic, 8 adenomatous and 60 pediatric thyroid cancers (13 follicular thyroid cancers [FTC] and 47 papillary thyroid cancers [PTC]) of which 8 had DICER1 RNase IIIb mutations. All DICER1-mutant differentiated thyroid cancers (DTC) were follicular patterned (six follicular variant PTC and two FTC), none had lymph node metastasis. We demonstrate that DICER1 pathogenic somatic mutations were associated with a global reduction of 5p-derived miRNAs, including those particularly abundant in the non-neoplastic thyroid tissue such as let-7 and mir-30 families, known for their tumor suppressor function. There was also an unexpected increase of 3p miRNAs, possibly associated with DICER1 mRNA expression increase in tumors harboring RNase IIIb mutations. These abnormally expressed 3p miRNAs, which are otherwise low or absent in DICER1-wt DTC and non-neoplastic thyroid tissues, make up exceptional markers for malignant thyroid tumors harboring DICER1 RNase IIIb mutations. The extensive disarray in the miRNA transcriptome results in gene expression changes, which were indicative of positive regulation of cell-cycle. Moreover, differentially expressed genes point to increased MAPK signaling output and loss of thyroid differentiation comparable to the RAS-like subgroup of PTC (as coined by The Cancer Genome Atlas), which is reflective of the more indolent clinical behavior of these tumors.

Cytomorphological and Clinical Features of Follicular Variant Papillary Thyroid Carcinoma (With Focal Insular Pattern) Metastasis to Kidney.

Cytomorphological and Clinical Features of Follicular Variant Papillary Thyroid Carcinoma (With Focal Insular Pattern) Metastasis to Kidney.

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.

Combined Cyclin D2 and Protein Convertase 2 Genes in Differentiating Various Follicularpatterned Lesions and Neoplasms of the Thyroid: A Cross-sectional Study

Introduction: A pretherapeutic distinction between benign and malignant thyroid nodules is critical for the clinical management of patients presenting with thyroid nodules. However, certain follicular-patterned lesions, such as adenomatous nodules, follicular neoplasms comprising Follicular Adenoma (FA) and Follicular Carcinoma (FC), as well as the Follicular Variant of Papillary Thyroid Carcinoma (FVPTC), can pose a significant dilemma during pre-therapeutic Fine Needle Aspiration Cytology (FNAC) evaluation. The present (pilot) study explores the possible utility of messenger Ribonucleic Acid (mRNA) and the protein expression of the two relatively less-explored genes, Cyclin D2 (CCND2) and Protein Convertase 2 (PCSK2), in distinguishing various follicular-patterned thyroid lesions and neoplasms by testing these molecular markers initially on histopathological sections. Aim: To assess the RNA and protein expressions of CCND2 and PCSK2 genes in differentiating follicular-patterned thyroid neoplasms. Materials and Methods: This was a cross-sectional analytical study conducted over 6 years, from August 2014 to August 2020, at the Department of Pathology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India. Real-Time quantitative Polymerase Chain Reaction (RT-qPCR) along with Immunohistochemistry (IHC) was performed on a total of 75 tissue samples from follicularpatterned thyroid lesions and neoplasms, including 19 Follicular Hyperplasias (FHs), 10 Nodular Goitres (NGs), 17 FAs, 8 FCs, and 12 FVPTCs, along with nine Conventional Papillary Thyroid Carcinomas (CPTCs). After confirming the RNA and protein expression levels in each of these lesions, Immunoreactive Scoring (IRS) was performed to assess their IHC expression. The Kruskal-Wallis and Analysis of Variance (ANOVA) tests were used to analyse the mRNA expression data, and Pearson analysis was conducted to correlate the IHC data between the study groups. A p-value of &lt;0.05 was considered statistically significant. Results: Among the 75 thyroid lesions studied, both NG and FA showed a relatively higher cyclinD2 mRNA expression, with fold changes of 1.21 and 1.46, respectively. This was also reflected in IHC, with moderate nuclear expression observed in these cases. The PCSK2 mRNA expression was similar to that of CCND2, with the only difference noted between FH and FA. On IHC, eight out of 75 cases had positive PCSK2 expression, including five FHs, two FVPTCs, and one FA, while the remaining 67 cases were negative. Conclusion: The CCND2 and PCSK2 genes assessed in the present study, regarding their mRNA and protein expressions, were not found to be of any practical value in distinguishing benign and malignant follicular lesions or neoplasms of the thyroid.