Whole-exome sequencing of atypical parathyroid tumors detects novel and common genes linked to parathyroid tumorigenesis.

CONTEXT: Atypical parathyroid tumor (APT) represents a neoplasm characterized by histological features typical of parathyroid carcinoma (PC) but lacking local infiltration and/or distant metastasis, leading to uncertainty regarding its malignant potential. OBJECTIVE: To characterize the molecular landscape and deregulated pathways in APT. METHODS: Whole exome sequencing (WES) was conducted on 16 APTs. DNA from tumors and matched peripheral blood underwent WES using Illumina HiSeq3000. RESULTS: A total of 192 nonsynonymous variants were identified. The median number of protein-altering mutations was 9. The most frequently mutated genes included BCOR, CLMN, EZH1, JAM2, KRTAP13-3, MUC16, MUC19, and OR1S1. Seventeen mutated genes belong to the Cancer Gene Census list. The most consistent hub genes identified through STRING network analysis were ATM, COL4A5, EZH2, MED12, MEN1, MTOR, PI3, PIK3CA, PIK3CB, and UBR5. Deregulated pathways included the PI3 K/AKT/mTOR pathway, Wnt signaling, and extracellular matrix organization. Variants in genes such as MEN1, CDC73, EZH2, PIK3CA, and MTOR, previously reported as established or putative/candidate driver genes in benign adenoma (PA) and/or PC, were also identified in APT. CONCLUSIONS: APT does not appear to have a specific molecular signature but shares genomic alterations with both PA and PC. The incidence of CDC73 mutations is low, and it remains unclear whether these mutations are associated with a higher risk of recurrence. Our study confirms that PI3 K/AKT/mTOR and Wnt signaling represents the pivotal pathways in parathyroid tumorigenesis and also revealed mutations in key epigenetic modifier genes (BCOR, KDM2A, MBD4, and EZH2) involved in chromatin remodeling, DNA, and histone methylation.

Identification of a Novel Non-V600E BRAF Mutation in Papillary Thyroid Cancer.

Papillary thyroid cancer (PTC) is a common endocrine malignancy, and its incidence is reported to be constantly increasing. BRAF mutation is detected in approximately 44% of PTCs, and the most common BRAF mutation is thymine (T) to adenine (A) missense mutation in nucleotide 1796 (T1796A, V600E). Although BRAFV600E represents 95% of all BRAF mutations, uncommon BRAF mutations have been reported in thyroid carcinomas and represent an alternative mechanism of BRAF activation with unclear clinical significance. We report a novel non-V600E mutation (c.1799_1812delinsAT, p.V600_W604delinsD), identified preoperatively with next-generation sequencing (NGS) on the material obtained with fine-needle aspiration cytology (FNAC) performed on a thyroid nodule cytologically suspicious for malignancy in a 35-year-old male patient. The presence of this new variant of BRAF mutation was subsequently confirmed in the postoperative phase by direct Sanger sequencing. In conclusion, we report a new non-V600E variant previously undetected in papillary thyroid cancer. In addition, this case report shows that the NGS technique on cytological tissue allows to detect the presence of rare mutations, thus increasing the diagnostic specificity of molecular analysis.

Nodal metastasis in noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP).

The term noninvasive tumor with a follicular growth pattern and nuclear features of papillary thyroid cancer (NIFTP) is used to describe a tumor currently considered as a pre-malignant lesion for which a conservative therapeutic approach (i.e., lobectomy without radioiodine therapy) is strongly suggested. However, some patients with NIFTP and loco-regional or distant metastases have been already reported. We present an adult male patient with a final histological diagnosis of NIFTP and lymph node metastasis noted at post-therapy whole-body scintigraphy performed some days after radioiodine therapy.

BRAF K601E Mutation in Oncocytic Carcinoma of the Thyroid: A Case Report and Literature Review.

BACKGROUND: Thyroid carcinoma (TC) is the most common endocrine cancer, with papillary thyroid carcinoma (PTC) being the most common subtype. BRAF and RAS oncogene were characterized as the most frequently altered genes in PTC, with a strong association between genotype and histotype. The most common mutation in BRAF gene is V600E and is prevalent in classic and aggressive variants of PTC, while BRAF K601E mutation is the most common among the other rare BRAF mutations. BRAF K601E mutated thyroid carcinomas are usually characterized by low aggressiveness, except for anecdotal cases of poorly differentiated TC. CASE PRESENTATION: We described a case of oncocytic carcinoma of the thyroid (OCA) with an aggressive clinical course, including widespread metastasis and resistance to radioiodine treatment. Molecular analysis revealed the exclusive presence of the BRAF K601E mutation in both primary tumor and metastatic lesions. Accordingly, a revision of the literature about aggressive TC cases carrying BRAF K601E mutation was performed. CONCLUSION: Although rare, this case emphasizes the relevance of considering BRAF K601E mutation in advanced non-PTC thyroid carcinomas, since it can be considered an actionable mutation for target therapies.

Usefulness of second 131I treatment in biochemical persistent differentiated thyroid cancer patients.

Background: Second 131I treatment is commonly performed in clinical practice in patients with differentiated thyroid cancer and biochemical incomplete or indeterminate response (BiR/InR) after initial treatment. Objective: The objective of the is study is to evaluate the clinical impact of the second 131I treatment in BiR/InR patients and analyze the predictive factors for structural incomplete response (SiR). Patients and methods: One hundred fifty-three BiR/InR patients after initial treatment who received a second 131I treatment were included in the study. The clinical response in a short- and medium- long-term follow-up was evaluated. Results: After the second 131I treatment (median 8 months), 11.8% patients showed excellent response (ER), 17% SiR, while BiR/InR persisted in 71.2%. Less than half (38.5%) of SiR patients had radioiodine-avid metastases. Patients who, following the second 131I treatment, experienced SiR had larger tumor size and more frequently aggressive histology and vascular invasion than those experienced BiR/InR and ER. Also, the median values of thyroglobulin on levothyroxine therapy (LT4-Tg), Tg peak after recombinant human TSH stimulation (rhTSH-Tg) and thyroglobulin antibodies (TgAb) were significantly higher in patients who developed SiR. At last evaluation (median: 9.9 years), BiR/InR persisted in 57.5%, while 26.2% and 16.3% of the patients showed ER and SiR, respectively. About half of BiR/InR patients (71/153 (46.4%)) received further treatments after the second 131I treatment. Conclusions: Radioiodine-avid metastatic disease detected by the second 131I is an infrequent finding in patients with BiR/InR after initial treatment. However, specific pathologic and biochemical features allow to better identify those cases with higher probability of developing SiR, thus improving the clinical effectiveness of performing a second 131I treatment.

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.

Approach to the Patient With Parathyroid Carcinoma.

Parathyroid carcinoma (PC) is usually associated with severe symptomatic primary hyperparathyroidism (PHPT) and accounts for less than 1% of all cases of PHPT and approximately 0.005% of all cancers. PC most commonly occurs as a sporadic disease and somatic CDC73 mutations can be detected in up to 80% of cases. Approximately 30% of patients harbor a germline mutation of the CDC73 gene. Preoperative diagnosis of PC is difficult because no disease-specific markers are available, and PC should be suspected in patients with severe hypercalcemia and end-organ complications. The diagnosis is based on the evidence of invasive tumor growth at histology and/or metastases. En bloc resection of the tumor, together with the ipsilateral thyroid lobe and adjacent structures, should be performed by an experienced surgeon when PC is suspected. This surgical approach reduces the risk of recurrence and metastasis and offers the highest chance of cure. Nonetheless, PC has a recurrence rate of 40% to 60% and, if feasible, multiple surgical procedures should be performed. When surgery is no longer an option, medical treatment is aimed to reduce hypercalcemia and target organ complications. Targeted agents have been effectively used in a few cases. We describe herein a patient with severe PHPT due to PC and provide a systematic diagnostic and treatment approach. A thorough review of the medical history, a typical clinical and biochemical phenotype and, in some cases, the revision of the histological examination provide the clues for the diagnosis of PC.

Chromosomal alterations in sporadic medullary thyroid carcinoma and correlation with outcome.

Somatic copy number alterations (SCNA) involving either a whole chromosome or just one of the arms, or even smaller parts, have been described in about 88% of human tumors. This study investigated the SCNA profile in 40 well-characterized sporadic medullary thyroid carcinomas by comparative genomic hybridization array. We found that 26/40 (65%) cases had at least one SCNA. The prevalence of SCNA, and in particular of chromosome 3 and 10, was significantly higher in cases with a RET somatic mutation. Similarly, SCNA of chromosomes 3, 9, 10 and 16 were more frequent in cases with a worse outcome and an advanced disease. By the pathway enrichment analysis, we found a mutually exclusive distribution of biological pathways in metastatic, biochemically persistent and cured patients. In particular, we found gain of regions involved in the intracellular signaling and loss of regions involved in DNA repair and TP53 pathways in the group of metastatic patients. Gain of regions involved in the cell cycle and senescence were observed in patients with biochemical disease. Finally, gain of regions associated with the immune system and loss of regions involved in the apoptosis pathway were observed in cured patients suggesting a role of specific SCNA and corresponding altered pathways in the outcome of sporadic MTC.

Cytological and Ultrasound Features of Thyroid Nodules Correlate With Histotypes and Variants of Thyroid Carcinoma.

CONTEXT: Prognosis is excellent for papillary thyroid carcinoma (PTC), noninvasive follicular thyroid neoplasia with papillary-like nuclear features (NIFT-P), and follicular thyroid carcinoma (FTC) but is poor for poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma (ATC). Among PTCs, the prognosis is more favorable for follicular (FV-PTC) and classic (CV-PTC) than for tall cell (TCV-PTC), and solid (SV-PTC) variants. OBJECTIVE: To associate histotypes and variants of thyroid carcinoma with ultrasound and cytological features. METHODS: Histology of 1018 benign tumors and 514 PTC (249 CV, 167 FV, 49 TC, 34 SV, and 15 other variants), 52 NIFT-P, 50 FTC, 11 PDTC, and 3 ATC was correlated with fine-needle aspiration biopsy categories (Italian classification: TIR1, TIR2, TIR3A, TIR3B, TIR4, and TIR5) and ultrasound features at the Endocrinology Unit, University Hospital of Pisa. In total, 1117 patients with thyroid nodule(s) who underwent thyroidectomy were included. RESULTS: Of PTC, 36.3% had indeterminate cytology (TIR3A or TIR3B), 56.6% were suspicious for malignancy or malignant (TIR4 or TIR5); 84.0% FTC and 69.3% NIFT-P were TIR3A or TIR3B; 72.5% FV-PTC and 73.6% SV-PTC were TIR3A or TIR3B; 79.9% CV-PTC and 95.9% TCV-PTC were TIR4 or TIR5. The association of a hypoechoic pattern, irregular margins, and no microcalcifications was more frequent in TCV-PTC than in CV-PTC (P = .02, positive predictive value = 38.9%; negative predictive value = 85.5%). CONCLUSION: At cytology, most FTC, NIFT-P, FV-PTC, and SV-PTC were indeterminate, most CV-PTC and TCV-PTC were suspicious for malignancy or malignant. Ultrasound can be helpful in ruling out TCV-PTC.

NF1 Gene Inactivation Acts as Tumor Driver in RET/RAS Negative Medullary Thyroid Carcinomas.

OBJECTIVE: 20% of sporadic MTC has no RET/RAS somatic alterations or other known gene alterations. Aim of this study was to investigate RET/RAS negative MTC for the presence of NF1 alterations. METHODS: we studied 18 sporadic RET/RAS negative MTC cases: Next generation sequencing of tumoral and blood DNA was performed using a custom panel including the entire coding region of the NF1 gene. The effect of NF1 alterations on the transcripts were characterized by RT-PCR and the loss of heterozygosity of the other NF1 allele was investigated with Multiplex Ligation-dependent Probe Amplification. RESULTS: Two cases showed bi-allelic inactivation of NF1 with a prevalence of about 11% of RET/RAS negative cases. In a patient affected by neurofibromatosis there was a somatic intronic point mutation determining the transcript alteration in one allele and a germline loss of heterozygosity (LOH) in the other. In the other case described both the point mutation and the LOH were somatic events; this latter finding shows, for the first time, a driver role of NF1 inactivation in MTC independent of RET/RAS alterations and the presence of neurofibromatosis. CONCLUSIONS: About 11% of our series of sporadic RET/RAS negative MTC harbor biallelic inactivation of NF1 suppressor gene also regardless neurofibromatosis status. According to our results, NF1 alterations should be searched in all RET/RAS negative MTC as possible driver. Moreover, this finding reduces the number of negative sporadic MTCs and may have important clinical implications in the management of these tumors.

An adrenal cortical adenoma with neuroendocrine-type granules mimicking pheochromocytoma.

Clinical and biochemical presentation of adrenal tumors may rarely conflict with their histologic features. In the present report, we describe a rare case of adrenal neoplasm clinically and biochemically labeled as pheochromocytoma which at histologic examination resulted adrenal cortical tumor. The neoplasm was examined with the electron microscope which revealed the presence of electron-dense neuroendocrine-type granules next to intracytoplasmic lipid droplets. The patient underwent laparoscopic left adrenalectomy which leads to normalization of 24 h urinary metanephrine and normetanephrine. This exceptional entity should be taken into consideration when the clinical and laboratory features conflict with the histological examination. The pathologist can clarify the mixed nature of the tumor by means of the identification of neuroendocrine granules at the electron microscope examination.

Outcomes of the Tall-Cell Variant of Papillary Thyroid Carcinoma in Patients with Different Ages: A 17-Year Mono-Institutional Experience.

The tall-cell variant of papillary thyroid carcinoma (TCPTC) is the most common aggressive variant of papillary thyroid carcinoma (PTC) and typically occurs in older patients. In this study, we analyzed retrospectively the largest mono-institutional series of PTCs with tall-cell features (989 patients) over a 17-year period, re-evaluating tumors based on age at presentation and outcomes in different age groups. We divided patients into three age groups following different criteria (the criterion from the American Joint Committee on Cancer Tumor Node Metastasis (AJCC TNM) guidelines, criterion for the statistical division into tertiles and adolescent/post-adolescent criterion) to analyze the clinicopathological characteristics in different age groups, especially in terms of recurrence-free survival (RFS) and distant recurrence-free survival (DRFS). We obtained three main results: 1. the population is distributed among the different age groups, and therefore, this type of cancer is not exclusively found among those of an older age; 2. in the RFS analysis, we can see a higher probability of local recurrence in the younger and older groups and, unexpectedly, a lower probability of local recurrence in the "median age" group; and 3. in the DRFS analysis, we can observe a higher probability of distant recurrence in older patients. From a molecular perspective, no significant differences in the mutational status of BRAF were detected according to different age groups, while mutations in the TERT promoter were exclusively present in older patients of all age groups, highlighting the potential prognostic implications of TERT promoter mutations in PTCs. In conclusion, the results of this series confirm that TC morphology alone in PTCs does not have the same negative prognostic significance in the younger population as in the older population. The reason for these different outcomes remains unclear and needs further studies.

The 5th edition of WHO classification of tumors of endocrine organs: changes in the diagnosis of follicular-derived thyroid carcinoma.

The 5th edition of the World Health Organization (WHO) classification of endocrine tumors was released in 2022. Several novelties have been introduced concerning the nomenclature and histopathological diagnosis of follicular-derived thyroid neoplasms. Tumor types have been sharply classified according to prognostic risk categories into benign tumors, low-risk neoplasms and malignant neoplasms. A grading system for differentiated thyroid carcinomas has been implemented with the aim of improving the stratification of tumors. Particular attention has been paid to the molecular profile of well-differentiated histotypes. In this review, the main changes introduced by the latest edition of the WHO system are presented. The practical effects on the diagnostic pathology of thyroid tumors, along with the clinical implications expected with the new classification scheme, are critically discussed.

Clinical Evolution of Sporadic Medullary Thyroid Carcinoma With Biochemical Incomplete Response After Initial Treatment.

CONTEXT: The clinical response after surgery is a determinant in the management of patients with medullary thyroid carcinoma (MTC). In case of excellent or structural incomplete response, the follow-up strategies are well designed. Conversely, in case of biochemical incomplete response (BiR) the management is not clearly defined. OBJECTIVE: This work aimed to evaluate the overall and per-site prevalence of structural disease detection in sporadic MTC patients with BiR and to assess the predictive value of various clinical, biochemical, and genetic features. METHODS: We evaluated data of 599 consecutive patients surgically treated for sporadic MTC (2000-2018) and followed-up at the endocrine unit of the University Hospital of Pisa. RESULTS: After a median of 5 months from surgery, 145 of 599 (24.2%) patients were classified as BiR. Structural disease was detected in 64 of 145 (44.1%), after a median time of 3.3 years. In 73.6%, structural disease was detected at a single site, prevalently cervical lymph nodes. Among several others, at the time of first evaluation after surgery, only basal calcitonin (bCTN) and stage IVa/b were independent predictive factors. Also, structural disease was more frequent in patients with shorter CTN doubling time and somatic RET mutation. CONCLUSION: In sporadic MTC patients with BiR, the risk of detection of structural disease was about 50% at 10 years. Higher bCTN levels and staging predicted the risk of detecting structural disease. According to these findings, stricter follow-up should be reserved for MTC with BiR and elevated values of bCTN and to those with an advanced stage. Long follow-up should be considered for all BiR patients since 50% of them develop structural disease within 10 years.

High Incidence of Thyroid Cancer in Southern Tuscany (Grosseto Province, Italy): Potential Role of Environmental Heavy Metal Pollution.

The incidence of thyroid cancer (TC) in Italy is one of the highest in Europe, and the reason for this is unclear. The intra-country heterogeneity of TC incidence suggests the possibility of an overdiagnosis phenomenon, although environmental factors cannot be excluded. The aim of our study is to evaluate the TC incidence trend in southern Tuscany, Italy, an area with particular geological characteristics, where the pollution and subsequent deterioration of various environmental matrices with potentially toxic elements (heavy metals) introduced from either geological or anthropogenic (human activities) sources are documented. The Tuscany cancer registry (ISPRO) provided us with the number of cases and EU standardized incidence rates (IR) of TC patients for all three provinces of southeast Tuscany (Siena, Grosseto, Arezzo) during the period of 2013-2016. In addition, we examined the histological records of 226 TC patients. We observed that the TC incidence rates for both sexes observed in Grosseto Province were significantly higher than those observed in the other two provinces. The increase was mostly due to the papillary (PTC) histotype (92% of cases), which presented aggressive variants in 37% of PTCs and tumor diameters more than 1 cm in 71.3% of cases. We demonstrated a high incidence of TC in Grosseto province, especially among male patients, that could be influenced by the presence of environmental heavy metal pollution.

Autopsy Study of Testicles in COVID-19: Upregulation of Immune-Related Genes and Downregulation of Testis-Specific Genes.

CONTEXT: Infection by SARS-CoV-2 may be associated with testicular dysfunction that could affect male fertility. OBJECTIVE: Testicles of fatal COVID-19 cases were investigated to detect virus in tissue and to evaluate histopathological and transcriptomic changes. METHODS: Three groups were compared: (a) uninfected controls (subjects dying of trauma or sudden cardiac death; n = 10); (b) subjects dying of COVID-19 (virus-negative in testes; n = 15); (c) subjects dying of COVID-19 (virus-positive in testes; n = 9). SARS-CoV-2 genome and nucleocapsid antigen were probed using RT-PCR, in situ hybridization, and immunohistochemistry (IHC). Infiltrating leukocytes were typed by IHC. mRNA transcripts of immune-related and testis-specific genes were quantified using the nCounter method. RESULTS: SARS-CoV-2 was detected in testis tissue of 9/24 (37%) COVID-19 cases accompanied by scattered T-cell and macrophage infiltrates. Size of testicles and counts of spermatogenic cells were not significantly different among groups. Analysis of mRNA transcripts showed that in virus-positive testes immune processes were activated (interferon-alpha and -gamma pathways). By contrast, transcription of 12 testis-specific genes was downregulated, independently of virus positivity in tissue. By IHC, expression of the luteinizing hormone/choriogonadotropin receptor was enhanced in virus-positive compared to virus-negative testicles, while expression of receptors for androgens and the follicle-stimulating hormone were not significantly different among groups. CONCLUSION: In lethal COVID-19 cases, infection of testicular cells is not uncommon. Viral infection associates with activation of interferon pathways and downregulation of testis-specific genes involved in spermatogenesis. Due to the exceedingly high numbers of infected people in the pandemic, the impact of virus on fertility should be further investigated.

The Italian Consensus for the Classification and Reporting of Thyroid Cytology: Cytohistologic and molecular correlations on 37,371 nodules from a single institution.

BACKGROUND: The Italian Consensus for the Classification and Reporting of Thyroid Cytology (ICCRTC) includes six diagnostic categories (TIR 1/1C, TIR 2, TIR 3A, TIR 3B, TIR 4, and TIR 5), each indicating a different risk of malignancy. The objective of this monocentric retrospective study was to evaluate the distribution of the ICCRTC classes at the authors' institution and assess their cytohistologic correlations. METHODS: The authors retrospectively collected 37,371 consecutive cytologic reports of thyroid nodules and described the clinical-pathologic features of the different cytologic categories. The cytologic diagnoses also were compared with histologic outcomes in a subset of patients. RESULTS: The cytologic classes were distributed as follows: nondiagnostic, 15.6%; benign, 66.5%; low-risk indeterminate, 10% (TIR 3A); high-risk indeterminate, 3.5% (TIR 3B); suspicious, 1.7%; and malignant, 2.6%. According to histology, the risk of malignancy was very high in the nondiagnostic category (29.8%), with young male patients more exposed to malignancy, and it was relatively high among benign (7.8%) and indeterminate nodules (32.5% in TIR 3A; 52.1% in TIR 3B), mainly because of the high prevalence of follicular architecture in malignant tumors. On histology, the malignancy rates were 92.4% and 99.3% for the suspicious and malignant categories, respectively; aggressive variants of papillary thyroid carcinoma were mostly diagnosed in these categories. CONCLUSIONS: In this series, nondiagnostic nodules showed high prevalence and, surprisingly, high malignancy rates. Malignant tumors with follicular architecture represented a diagnostic pitfall in benign and indeterminate nodules. The suspicious and malignant categories had high specificity for malignancy. Importantly, the ICCRTC had high reliability for identifying preoperatively aggressive histotypes of thyroid carcinoma.

Predictive Biomarkers in Thyroid Cancer.

In molecular pathology, predictive biomarkers identify which patients are likely to respond to targeted drugs. These therapeutic agents block specific molecules directly involved in cancer growth, dedifferentiation and progression. Until few years ago, the only targeted drugs available for advanced thyroid cancer included multi-tyrosine kinase inhibitors, mainly targeting the MAPK pathway and the angiogenic signaling. The administration of these drugs does not necessarily require a molecular characterization of tumors to assess the presence of predictive alterations. However, the availability of new selective targeted drugs for thyroid cancer patients is changing the diagnostic strategies for the molecular characterization of these tumors. The search for targetable alterations can be performed directly on tumor tissue by using a variety of methodologies, depending also on the number and type of alterations to test (i.e. single nucleotide variation or gene rearrangement). Herein, a comprehensive review of the currently available targeted treatments for thyroid cancer, related predictive markers and testing methodologies is provided.

Somatic RET Indels in Sporadic Medullary Thyroid Cancer: Prevalence and Response to Selpercatinib.

CONTEXT: Although the majority of RET alterations are single nucleotide variants (SNV), small deletions and/or insertions have been reported at variable prevalence. No information about the efficacy of RET-specific inhibitors in patients harboring RET indels has been provided. OBJECTIVE: We present an update on the prevalence of RET indels in medullary thyroid cancer (MTC) and describe the efficacy of selpercatinib in patients with advanced MTC with RET indels. METHODS: The MTC tissues of 287 patients were analyzed using an Ion S5 targeted sequencing. The functional role of the reported indels have been evaluated by MutationTaster. Clinical and pathological data of MTC patients harboring a RET indel were collected and analyzed. Two patients with a RET indel were treated with selpercatinib. RESULTS: Among 178 RET-positive cases, 147 (82.6%) harbored a SNV and 31 (17.4%) a RET in-frame indel. Nine indels were not previously reported and were found to be disease causing by MutationTaster. Patients harboring an indel were found to have an aggressive disease and 2 of them were treated with selpercatinib, experiencing a good response to the treatment. CONCLUSION: These data show that RET indels are not infrequent and correlate with an aggressive disease. Two RET indel-positive patients showed a partial response to the treatment with a highly selective RET inhibitor; thus, these RET indels can be considered actionable mutations. In order to not miss these alterations, the analysis of the full gene is recommended.

Sclerosing Paragangliomas: Correlations of Histological Features with Patients' Genotype and Vesicular Monoamine Transporter Expression.

Paragangliomas and pheochromocytomas are rare neuroendocrine tumors, carrying a germ-line mutation in 40% patients. Sclerosis is a rare histological feature in these tumors. We investigated the possible correlations between histological findings, first sclerosis, immunoreactivity for vesicular catecholamine transporters (VMAT1/VMAT2) and patients' genotype in a consecutive series of 57 tumors (30 paragangliomas and 27 pheochromocytomas) from 55 patients. The M-GAPP grading system, sclerosis (0-3 scale) and VMAT1/VMAT2 (0-6 scale) immunoreactivity scores were assessed. Germ-line mutations of Succinate Dehydrogenase genes, RET proto-oncogene and Von Hippel Lindau tumor suppressor gene were searched. A germ-line mutation was found in 25/55 (45.5%) patients, mainly with paraganglioma (N = 14/30, 46,66%). Significant (score ≥ 2) tumor sclerosis was found in 9 (16.1%) tumors, i.e., 7 paragangliomas and 2 pheochromocytomas, most of them (8/9) from patients with a germ-line mutation. M-GAPP score was higher in the mutation status (in 76% of patients involving the SDHx genes, in 12% the RET gene and in the remaining 12% the VHL gene) and in tumors with sclerosis (p < 0.05). Spearman's rank correlation showed a strong correlation of germ-line mutations with M-GAPP (p < 0.0001) and sclerosis (p = 0.0027) scores; a significant correlation was also found between sclerosis and M-GAPP scores (p = 0.029). VMAT1 expression was higher in paragangliomas than in pheochromocytomas (p = 0.0006), the highest scores being more frequent in mutation-bearing patients' tumors (p < 0.01). VMAT2 was highly expressed in all but two negative tumors. Sclerosis and VMAT1 expression were higher in paragangliomas than in pheochromocytomas; tumor sclerosis, M-GAPP and VMAT1 scores were associated to germ-line mutations. Sclerosis might represent a histological marker of tumor susceptibility, prompting to genetic investigations in paragangliomas.