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The RET receptor tyrosine kinase plays a pivotal role in cell survival, proliferation, and differentiation, and its abnormal activation leads to cancers through receptor fusions or point mutations. Mutations that disrupt the disulfide network in the extracellular domain (ECD) of RET drive multiple endocrine neoplasia type 2A (MEN2A), a hereditary syndrome associated with the development of thyroid cancers. However, structural details of how specific mutations affect RET are unclear. Here, we present the first structural insights into the ECD of the RET(C634R) mutant, the most common mutation in MEN2A. Using electron microscopy, we demonstrate that the C634R mutation causes ligand-independent dimerization of the RET ECD, revealing an unusual tail-to-tail conformation that is distinct from the ligand-induced signaling dimer of WT RET. Additionally, we show that the RETC634R ECD dimer can form complexes with at least two of the canonical RET ligands and that these complexes form very different structures than WT RET ECD upon ligand binding. In conclusion, this structural analysis of cysteine-mutant RET ECD suggests a potential key mechanism of cancer induction in MEN2A, both in the absence and presence of its native ligands, and may offer new targets for therapeutic intervention.

Multiple endocrine neoplasia (MEN) is a rare inherited disease caused by multiple complex mutations in the RET gene. It is characterized by the occurrence of tumors involving more than two endocrine glands in the same patient. MEN is classified into two types: MEN type 1 (Wermer syndrome) and MEN type 2, which is further subclassified into two phenotypes: MEN 2A (Sipple syndrome) and MEN 2B (Shimcke syndrome). Sipple syndrome is the most common type of MEN type 2. It is characterized by the presence of medullary thyroid carcinoma (MTC), unilateral or bilateral pheochromocytoma, and primary hyperparathyroidism due to parathyroid cell hyperplasia or adenoma. In this article, the authors report a case of a 34-year-old Libyan woman with Rh positive B blood group who presented with an enlarged neck mass. Based on clinical, radiological, biochemical, and cytological assessments, the mass was diagnosed as MTC. Two weeks apart, the patient underwent right adrenalectomy and total thyroidectomy, while the parathyroid glands were found to be normal and preserved. In cases where a neck mass is the only symptom manifestation, it is crucial to carefully investigate for other MEN 2A findings, especially if there is a family history of MTC, to ensure a good prognosis. Patients with MEN 2A should undergo regular screening and be managed by a multidisciplinary team.

Multiple endocrine neoplasia (MEN) is a rare inherited disease caused by multiple complex mutations in the RET gene. It is characterized by the occurrence of tumors involving more than two endocrine glands in the same patient. MEN is classified into two types: MEN type 1 (Wermer syndrome) and MEN type 2, which is further subclassified into two phenotypes: MEN 2A (Sipple syndrome) and MEN 2B (Shimcke syndrome). Sipple syndrome is the most common type of MEN type 2. It is characterized by the presence of medullary thyroid carcinoma (MTC), unilateral or bilateral pheochro-mocytoma, and primary hyperparathyroidism due to parathyroid cell hyperplasia or adenoma. In this article, the authors report a case of a 34-year-old Libyan woman with Rh positive B blood group who presented with an enlarged neck mass. Based on clinical, radiological, biochemical, and cytological assessments, the mass was diagnosed as MTC. Two weeks apart, the patient underwent right adrenalectomy and total thyroidectomy, while the parathyroid glands were found to be normal and preserved. In cases where a neck mass is the only symptom manifestation, it is crucial to carefully investigate for other MEN 2A findings, especially if there is a family history of MTC, to ensure a good prognosis. Patients with MEN 2A should undergo regular screening and be managed by a multidisciplinary team. [ABSTRACT FROM AUTHOR]

Multiple endocrine adenomatosis type 2A (MEN2A) is a subtype of multiple endocrine adenomatosis type 2, which is clinically characterized by medulloid thyroid carcinoma (MTC) , pheochromocytoma (PHEO) , and hyperparathyroidism, and has been reported to be caused by mutations in the RET proto-oncogene on chromosome 10. We reported a case of MEN2A caused by RET proto-oncogene C634Y mutation, and conducted a pedigree analysis of the patient. Genetic test results showed C634Y mutation in the patient's siblings and their offspring. The diagnosis and treatment of this case in combination with a review of the relevant literature suggest that endocrine gland tests and RET proto-oncogene test should be performed for a patient diagnosed with endocrine adenomatosis to reduce the possibility of misdiagnosis and missed diagnosis, and to achieve early treatment, improve the effect of treatment and the prognosis of patients. In addition, the first- and second-degree relatives of the patient should also be tested for the mutation of the RET proto-oncogene.

This article discusses a case study of a 46-year-old woman who presented with corneal nerve thickening (CNT), a characteristic feature of multiple endocrine neoplasia (MEN) type 2B. However, genetic testing revealed that she had a new lineage of MEN2A, which is typically associated with medullary thyroid carcinoma (MTC), phaeochromocytoma, and primary hyperparathyroidism. The article highlights that while CNT is commonly associated with MEN2B, it can also be present in MEN2A, emphasizing the importance of considering both syndromes when CNT is detected. The study also discusses the intrafamilial variation in the presence and degree of CNT in families with MEN2A. [Extracted from the article]

Context: Early genetic association studies yielded too high risk estimates for multiple endocrine neoplasia (MEN2A), suggesting a need for extended surgery. Objective: The objective was to delineate temporal changes in MEN2A presentation by birth cohort analyses. Methods: Birth cohort analyses (10-year increments; ≤1950 to 2011-2020) of carriers of rearranged during transfection (RET) mutations who underwent surgery for MEN2A. Results: Included in this study were 604 carriers (155 index, 445 nonindex, 4 additional patients), with 237 carriers harboring high-risk mutations, 165 carriers moderate--high risk mutations, and 202 carriers low--moderate risk mutations. With increasing recency of birth cohorts, there was a continual decline in index patients from 41-74% to 0% (P < .001) and of medullary thyroid cancer (MTC) from 96-100% to 0-33% (P < .001). Node metastases diminished from 62-70% to 0% (P ≤ .001; high and low--moderate risk mutations), whereas biochemical cure after thyroidectomy surged from 17-33% to 100% (P ≤ .019; high and low--moderate mutations). Surgical interventions for MEN2A-related tumors were performed increasingly earlier, causing median carrier age to fall: from 51-63 to 3-5 years at thyroidectomy (P < .001); from 46-51 to 24-25 years at first adrenalectomy (P ≤ .013; high and moderate--high risk mutations); and from 43.5-66 to 16.5-32 years at parathyroidectomy. MTC diameters were more effectively decreased from 14-32 to 1-4 mm (P ≤ 002) than pheochromocytoma diameters (nonsignificant). Conclusion: These insights into MEN2A presentation, adjusted by birth year, illustrate the shift from reactive to preventative medicine, enabling less extensive risk-reducing surgery. [ABSTRACT FROM AUTHOR]

Simple Summary: Multiple endocrine neoplasia 2A (MEN 2A) is a rare hereditary cancer syndrome, in which primary hyperparathyroidism (PHPT) is reported in up to 35% of affected individuals. Recent studies suggest a lower frequency and a milder course of PHPT in MEN 2A, but these studies often lack a strict definition of PHPT and are frequently carried out at smaller research centers. This could result in diverging and incomplete data. Consequently, we aimed to investigate PHPT in a complete nationwide cohort of MEN 2A to suggest a representative frequency and clinical course of PHPT. This may alter the information given to MEN 2A patients by their caretakers on the likelihood of developing PHPT and on the clinical course of PHPT. Studies of primary hyperparathyroidism (PHPT) in multiple endocrine neoplasia type 2A (MEN 2A) shows divergence in frequency, disease definition, reporting of clinical characteristics and traces of selection bias. This is a nationwide population-based retrospective study of PHPT in MEN 2A, suggesting a representative frequency, with complete reporting and a strict PHPT definition. The Danish MEN 2A cohort 1930–2021 was used. Of 204 MEN 2A cases, 16 had PHPT, resulting in a frequency of 8% (CI, 5–12). Age-related penetrance at 50 years was 8% (CI, 4–15). PHPT was seen in the American Thyroid Association moderate (ATA-MOD) and high (ATA-H) risk groups in 62% and 38% of carriers, respectively. Median age at PHPT diagnosis was 45 years (range, 21–79). A total of 75% were asymptomatic and 25% were symptomatic. Thirteen underwent parathyroid surgery, resulting in a cure of 69%, persistence in 8% and recurrence in 23%. In this first study with a clear PHPT definition and no selection bias, we found a lower frequency of PHPT and age-related penetrance, but a higher age at PHPT diagnosis than often cited. This might be affected by the Danish RET p.Cys611Tyr founder effect. Our study corroborates that PHPT in MEN 2A is often mild, asymptomatic and is associated with both ATA-MOD and ATA-H variants. Likelihood of cure is high, but recurrence is not infrequent and can occur decades after surgery. [ABSTRACT FROM AUTHOR]

This paper illustrates a rare syndrome of multiple endocrine neoplasia type 2A (MEN2A) in a family of three generations. In our case, the father, son and one daughter developed phaeochromocytoma (PHEO) and medullary thyroid carcinoma (MTC) over a period of 35 years. Because of the metachronous onset of the disease and lack of digital medical records in the past, the syndrome was not found until a recent fine needle aspiration of an MTC-metastasized lymph node from the son. All resected tumors from the family members were then reviewed and supplemented with immunohistochemical studies, previously wrong diagnoses were then corrected. Further molecular study of targeted sequencing also revealed a RET germline mutation (C634G) in the family tree including the three members with onset of the disease and one granddaughter who had no disease at the time of testing. Despite the syndrome being well-known, it may still be misdiagnosed because of its rarity and long disease onset. A few lessons can be learned from this unique case. Successful diagnosis requires high suspicion and surveillance and a tri-level methodology including a careful review of family history, pathology and genetic counselling. [ABSTRACT FROM AUTHOR]

Purpose: Vandetanib is well-tolerated in patients with advanced medullary thyroid carcinoma (MTC). Long-term outcomes and mechanisms of MTC progression have not been reported previously.Experimental Design: We monitored toxicities and disease status in patients taking vandetanib for hereditary, advanced MTC. Tumor samples were analyzed for molecular mechanisms of disease progression.Results: Seventeen patients [8 male, age 13 (9-17)* years] enrolled; 16 had a RET p.Met918Thr germline mutation. The duration of vandetanib therapy was 6.1 (0.1-9.7+)* years with treatment ongoing in 9 patients. Best response was partial response in 10, stable disease in 6, and progressive disease in one patient. Duration of response was 7.4 (0.6-8.7+)* and 4.9 (0.6-7.8+)* years in patients with PR and SD, respectively. Six patients died 2.0 (0.4-5.7)* years after progression. Median progression-free survival (PFS) was 6.7 years [95% confidence interval (CI): 2.3 years-undefined] and 5-year overall survival (OS) was 88.2% (95% CI: 60.6%-96.9%). Of 16 patients with a RET p.Met918Thr mutation, progression-free survival was 6.7 years (95% CI: 3.1-undefined) and 5-year overall survival was 93.8% (95% CI: 63.2%-99.1%). No patients terminated treatment because of toxicity. DNA sequencing of tissue samples (n = 11) identified an increase in copy number alterations across the genome as a potential mechanism of drug resistance [*median (range)].Conclusions: This study demonstrates that vandetanib is safe and results in sustained responses in children and adolescents with hereditary MTC. Our preliminary molecular data suggest that an increase in copy number abnormalities may be associated with tumor progression in hereditary MTC patients treated with vandetanib. Clin Cancer Res; 24(4); 753-65. ©2017 AACR.

There are no data on the impact of parent-of-origin effects on the expression of multiple endocrine neoplasia type 2A (MEN2A). The present study aimed to explore effects of parent-of-origin and offspring gender in MEN2A. In total, 224 carriers harbored heterozygous RET (REarranged during Transfection) p.Cys634 missense variants, for 169 of whom information on parent-of-origin gender was available. Altogether, offspring from affected fathers harbored more often node metastases from medullary thyroid cancer (45 vs. 19%; P = 0.006) and bilateral pheochromocytoma (24 vs. 10%; P = 0.021) than offspring from affected mothers. The former also also tended to be older at most recent follow-up (medians of 21 vs. 14 years; P = 0.056) and tended to have more often pheochromocytoma (33 vs. 19 yrs.; P = 0.051) and primary hyperparathyroidism (13 vs. 4%; P = 0.090) than the latter. Daughters from affected fathers harbored more often node metastases (39 vs. 15%; P = 0.043) than daughters from affected mothers. This difference decreased in male offspring when sons from affected fathers were compared with sons from affected mothers (52 vs. 40%; P = 0.111). There was also a slight deficit of male offspring: 1.1 sons each per affected mother and father vs. 1.2 daughters per affected mother and 1.4 daughters per affected father. These data suggest a parent-of-origin effect in MEN2A, warranting international collaborative research. [ABSTRACT FROM AUTHOR]

BackgroundMultiple endocrine neoplasia type 2 is an autosomal dominant inherited syndrome caused by activating mutations in the RET proto-oncogene. The RETK666N DNA variant was previously reported in two isolated medullary thyroid carcinoma (MTC) cases, but no family studies are available, and its oncogenic significance remains unknown.MethodsThe clinical features, genetic data, and family information of eight index MTC patients with a germline RETK666N variant were assessed.ResultsFour probands presented with MTC and extensive nodal metastasis, one with biopsy-confirmed distant metastasis. Two additional probands presented with localized disease. However, nodal status was not available. Of the final two probands, one had an incidental 1.5 mm MTC and C-cell hyperplasia uncovered after surgery for papillary thyroid carcinoma, and one had two foci of MTC (largest dimension 2.3 cm) detected after surgery for dysphagia. Genetic screening identified 16 additional family members carrying the K666N variant (aged 5-90 years), 11 of whom have documented evaluation for MTC. Of these, only two were found to have elevated basal serum calcitonin upon screening, and the remaining patients had calcitonin levels within the reference range. One patient who elected to have a thyroidectomy at 70 years of age was confirmed to have MTC. The other subject, 57 years old, elected surveillance. Four prophylactic thyroidectomies were performed, with one case of C-cell hyperplasia at 20 years and three cases that revealed normal pathology at ages 21, 30, and 30 years. None of the K666N DNA variant carriers had evidence of primary hyperparathyroidism or pheochromocytoma.ConclusionsFrom this case series, the largest such experience to date, it is concluded that the RETK666N variant is likely pathogenic and associated with low penetrance of MTC. However, the findings are insufficient to define its pathogenicity clearly and make firm recommendations for screening and treatment. Given the potential benefit associated with early detection of aberrant C-cell growth, and the noninvasive nature of genetic testing, "at risk" individuals should be screened, and if the K666N variant is identified, they should be managed using a personalized screening approach for detection of MTC.

Context: RET p.V804M is classified as a moderate risk mutation for familial medullary thyroid cancer (FMTC). There is a significant controversy on the management of patients carrying this mutation. We describe a family incidentally discovered to have this mutation and review the literature on RET p.V804M mutation. Results: The proband was born to first-degree relative parents. He was noticed to have hypertrophy of some parts of the body and vascular skin changes. Whole-exome sequencing of DNA extracted from a skin biopsy showed a mutation in the PIK3CA (c.3132T>G, p.ASN1044LYS). This variant was not found in DNA extracted from blood. This confirmed the diagnosis of CLOVES syndrome (Congenital Lipomatous Overgrowth, Vascular malformations, Epidermal nevi and Scoliosis, skeletal or spinal anomalies). Another incidentally found mutation in the skin biopsy and blood sample was RET p.V804M. Although there was no family history of MTC or MEN 2 syndromes, family screening revealed RET p.V804M mutation and FMTC in the proband's father, paternal grandmother, one sister, and one aunt. There was significant interfamilial heterogeneity in the age of presentation and pathology. A review of literature showed that RET p.V804M mutation is a moderate risk mutation associated with late-onset FMTC, usually at middle to old age. Conclusion: Despite the controversy and the heterogeneous presentation of patients with RET p.V804M mutation, our study and review of the literature suggest that this seemingly "low" risk mutation is associated with late-onset but potentially aggressive MTC. This indicates the need for follow-up and timely intervention based on calcitonin level elevation. [ABSTRACT FROM AUTHOR]

Objective: Multiple endocrine neoplasia type 2A (MEN 2A) is a rare syndrome caused by RET germline mutations and has been associated with primary hyperparathyroidism (PHPT) in up to 30% of cases. Recommendations on RET screening in patients with apparently sporadic PHPT are unclear. We aimed to estimate the prevalence of cases presenting with PHPT as first manifestation among MEN 2A i ndex cases and to characterize the former cases. Design and methods: An international retrospective multicenter study of 1085 MEN 2A index cases. Experts from MEN 2 centers all over the world were invited to participate. A total of 19 centers in 17 different countries provided registr y data of index cases followed from 1974 to 2017. Results: Ten cases presented with PHPT as their first manifestation of M EN 2A, yielding a prevalence of 0.9% (95% CI: 0.4–1.6). 9/10 cases were diagnosed with medullary thyroid carcinoma (MTC) in relation to parathyroid surgery and 1/10 was diagnosed 15 years after parathyroid surgery. 7/9 cases with full TNM data were node-positive at MTC diagnosis. Conclusions: Our data suggest that the prevalence of MEN 2A index cases that present with PHPT as their first manifestation is very low. The majority of i ndex cases presenting with PHPT as first manifestation have synchronous MTC and are often n ode-positive. Thus, our observations suggest that not performing RET mutation analysis in patients with apparently sporadic PHPT would result in an extremely low false-negative rate, if no other MEN 2A component, specifically MTC, are found during work-up or resecti on of PHPT.

BackgroundThe tyrosine kinase inhibitors (TKI) vandetanib and cabozantinib are approved as targeted therapies in advanced medullary thyroid carcinoma (MTC) with symptoms or high tumour burden. Only recently, toxicity in long-time TKI usage was analysed. However, little is known about the impact of TKI discontinuation on MTC disease course after longer-term therapy. Here, we report our experience in a series of 7 MTC patients with vandetanib treatment of up to 87 months followed by discontinuation for concerns of toxicity or due to side-effects. The discontinuation of TKI therapy is a relevant clinical scenario. To our knowledge we present the largest single center series on an important aspect of TKI management.MethodsRetrospective analysis of MTC patients with continued discontinuation of vandetanib treatment in a tertiary referral endocrine tumour centre. Analysis included a review of patients’ records for TKI indication, and treatment response as well indications for continued TKI discontinuation and follow-up by clinical assessment, calcitonin and CEA doubling times as well as imaging (ultrasound, CT).ResultsSeven MTC patients [6 sporadic MTC, 1 Multiple Endocrine Neplasie Type 2a (MEN2a)] with previous vandetanib treatment (median: 41 months; range 7-87 months) and continued TKI discontinuation were identified out of 161 analysed MTC files. TKI treatment was initiated due to high tumour burden and symptoms or RECIST (Response Evaluation Criteria In Solid Tumors) progression in all patients. Two patients (29%) remained stable after discontinuation of vandetanib until now (follow-up of 47 and 61 months). Both patients had been on TKI therapy for 73 and 58 months. Five patients (71%) developed progressive disease after TKI discontinuation. In 2 patients, vandetanib was restarted after 45 and 52 months resulting again in disease control. One patient was enrolled in a new RET kinase inhibitor trial after 45 months of vandetanib discontinuation. Two patients declined restart of treatment due to mental health issues leading to discontinuation of vandetanib in the first place (after 7 and 38 months of treatment) and both patients died of rapidly progressive disease. At time points of tumour progression, calcitonin-doubling time (CDT) was < 2 years in all patients.ConclusionThis case series suggests that discontinuation of long-term vandetanib treatment with documented stable disease does not automatically result in rapid disease progression but may be followed by prolonged “TKI free” stable disease in individual patients. Analysis of calcitonin and CDT during discontinuation is indicated as it will unmask tumour progression earlier than imaging. Restart with the same TKI is possible in case of progression.

Background: The tyrosine kinase inhibitors (TKI) vandetanib and cabozantinib are approved as targeted therapies in advanced medullary thyroid carcinoma (MTC) with symptoms or high tumour burden. Only recently, toxicity in long-time TKI usage was analysed. However, little is known about the impact of TKI discontinuation on MTC disease course after longer-term therapy. Here, we report our experience in a series of 7 MTC patients with vandetanib treatment of up to 87 months followed by discontinuation for concerns of toxicity or due to side-effects. The discontinuation of TKI therapy is a relevant clinical scenario. To our knowledge we present the largest single center series on an important aspect of TKI management. Methods: Retrospective analysis of MTC patients with continued discontinuation of vandetanib treatment in a tertiary referral endocrine tumour centre. Analysis included a review of patients' records for TKI indication, and treatment response as well indications for continued TKI discontinuation and follow-up by clinical assessment, calcitonin and CEA doubling times as well as imaging (ultrasound, CT). Results: Seven MTC patients [6 sporadic MTC, 1 Multiple Endocrine Neplasie Type 2a (MEN2a)] with previous vandetanib treatment (median: 41 months; range 7-87 months) and continued TKI discontinuation were identified out of 161 analysed MTC files. TKI treatment was initiated due to high tumour burden and symptoms or RECIST (Response Evaluation Criteria In Solid Tumors) progression in all patients. Two patients (29%) remained stable after discontinuation of vandetanib until now (follow-up of 47 and 61 months). Both patients had been on TKI therapy for 73 and 58 months. Five patients (71%) developed progressive disease after TKI discontinuation. In 2 patients, vandetanib was restarted after 45 and 52 months resulting again in disease control. One patient was enrolled in a new RET kinase inhibitor trial after 45 months of vandetanib discontinuation. Two patients declined restart of treatment due to mental health issues leading to discontinuation of vandetanib in the first place (after 7 and 38 months of treatment) and both patients died of rapidly progressive disease. At time points of tumour progression, calcitonin-doubling time (CDT) was < 2 years in all patients. Conclusion: This case series suggests that discontinuation of long-term vandetanib treatment with documented stable disease does not automatically result in rapid disease progression but may be followed by prolonged "TKI free" stable disease in individual patients. Analysis of calcitonin and CDT during discontinuation is indicated as it will unmask tumour progression earlier than imaging. Restart with the same TKI is possible in case of progression. [ABSTRACT FROM AUTHOR]

Multiple endocrine neoplasia type 2A (MEN2A) is a rare syndrome caused almost by germline RET mutation, and characterized by medullary thyroid carcinoma (MTC), in combination or not with pheochromocytoma (PHEO), hyperparathyroidism (HPTH), cutaneous lichen amyloidosis (CLA), and Hirschsprung's disease (HD). The basal serum calcitonin (Ctn)/carcinoembryonic antigen (CEA) levels are significantly correlated with the MTC stage. Metachronous surgery of MEN2A-specific tumors is a routine procedure. We aimed to explore the clinical significance of pro-gastrin-releasing peptide (proGRP) in MTC with elevated Ctn and simultaneous surgery of MEN2A-specific tumors. We retrospectively investigated 8 RET mutation carriers of 2 Chinese pedigrees with MEN2A. Clinical profiles, imaging examinations, preoperative and postoperative biochemical data, surgical procedures, and follow-up records were evaluated. Three patients showed levels of elevated Ctn but normal proGRP. Among them, one patient (FAIII-6) in Family A (one for RET C634R mutation), diagnosed with bilateral MTC, left PHEO, bilateral HPTH, and CLA, classified as MEN2A-related CLA subtype, underwent successfully simultaneous adrenal-sparing surgery (ASS), total thyroidectomy (TT), and parathyroidectomy, while TT of the other two patients (FBII-3 and FBIII-7) diagnosed with bilateral MTC in Family B (all for RET C618R mutation) were performed. Unexpectedly, the absence of neck lymph node MTC metastasis was indicated by histopathological examination. Postoperatively, all had consistently "undetectable" or normal levels of Ctn/CEA during follow-up. Patients with normal proGRP, despite high levels of Ctn, might have no regional lymph node MTC metastasis, and neck dissection should be avoided. Moreover, simultaneous surgery for coexistent PHEO and either MTC or HPTH is an approach of choice to use as an alternative treatment pattern. Recognition of MEN2A-related CLA and subsequently early screening of RET mutation may be favorable for timely management of MEN2A-specific tumors. [ABSTRACT FROM AUTHOR]

Objective: Diagnostic germline RET analysis is offered to all patients with a diagnosis of medullary thyroid carcinoma (MTC), or other conditions associated with multiple endocrine neoplasia type 2 (MEN2) in the United Kingdom. Here, we report the experience of a single centre's germline RET analysis over a 21‐year period. Design: Retrospective case‐note review. Patients: All index patients referred to the Exeter Genomics Laboratory for diagnostic germline RET analysis between 1997 and 2018, and unaffected family members, undergoing predictive testing. Measurements: The rate and nature of pathogenic variant detection were recorded, as well as the indication for testing. Results: 1,058 index patients and 551 unaffected family members were tested. The overall rate of pathogenic variant detection was 10.2% amongst index patients and 29% amongst unaffected family members. The commonest indication was isolated MTC, and amongst the 690 patients with isolated MTC, 68 (9.9%) were found to harbour a RET pathogenic variant. Of those with presumed sporadic MTC, 8.5% were found to harbour germline RET pathogenic variants, compared with 36.4% of those with a family history of MEN2‐associated conditions. Pathogenic variants were identified in 3.6% and 0% of patients with isolated phaeochromocytoma and primary hyperparathyroidism, respectively. Conclusions: Although the detection rate of RET germline pathogenic variants in patients with presumed sporadic MTC was significant, the overall detection rate in those with MTC was lower than expected in this series. Advances in RET analysis in response to reports of new variants over the last two decades are likely to have improved the pick‐up rate in recent years. [ABSTRACT FROM AUTHOR]

IntroductionProphylactic thyroidectomy can be curative for patients with hereditary medullary thyroid cancer (MTC) caused by RET proto-oncogene mutations. Calcitonin is a sensitive tumor marker used to follow patients. We suggest that thyroglobulin (Tg) levels should also be monitored postoperatively in these patients.MethodsWe reviewed patients with RET mutations who underwent prophylactic thyroidectomy between 1981 and 2011 at an academic endocrine surgery center. Patients were excluded if they had no postoperative Tg levels recorded.ResultsOf the 22 patients who underwent prophylactic thyroidectomy, 14 were included in the final analysis. The average age at thyroidectomy was 9.8 years (range, 4-29). Tg levels were detectable 1.5 months to 31 years postoperatively in 11 patients (79%), all of whom were

Abstract Patients with MEN2A with RET D631Y mutation most commonly present with pheochromocytomas. MTC is a less common part of the syndrome. Therefore, MEN2A caused by the RET D631Y mutation would be a benign nature.

Patients with MEN2A with RET D631Y mutation most commonly present with pheochromocytomas. MTC is a less common part of the syndrome. Therefore, MEN2A caused by the RET D631Y mutation would be a benign nature. [ABSTRACT FROM AUTHOR]

Adrenocortical carcinoma (ACC) is a rare aggressive malignancy that originates in the outer layer of the adrenal gland. Most ACCs are sporadic, but a small percentage of cases are due to hereditary cancer syndromes such as Li‐Fraumeni syndrome (LFS), Lynch syndrome (LS), and familial adenomatous polyposis (FAP). Multiple endocrine neoplasia type 2A (MEN2A) is an inherited disorder that predisposes to medullary thyroid cancer, pheochromocytoma, and parathyroid hyperplasia. We present here a case of ACC with both LS and MEN2A; the family and medical history were consistent with Lynch. This is, to our knowledge, the first report of a patient with ACC associated with germline mutations in RET and MSH2, and no phenotypical characteristics of MEN2A. [ABSTRACT FROM AUTHOR]

Background: Multiple endocrine neoplasia type 2 (MEN2) is a rare, autosomal dominant endocrine disease. Currently, the RET proto-oncogene is the only gene implicated in MEN2A pathogenesis. Once an RET carrier is detected, family members should be screened to enable early detection of medullary thyroid carcinoma, pheochromocytoma, and hyperparatitity. Among these, medullary thyroid carcinoma is the main factor responsible for patient mortality. Accordingly, delineating strategies to inform clinical follow-up and treatment plans based on genes is paramount for clinical practitioners., Case Summary: Herein, we present RET proto-oncogene mutations, clinical characteristics, and treatment strategies in a family with MEN2A. A family study was conducted on patients diagnosed with MEN2A. DNA was extracted from the peripheral blood of family members, and first-generation exon sequencing of the RET proto-oncogene was conducted. The C634Y mutation was identified in three family members spanning three generations. Two patients were sequentially diagnosed with pheochromocytomas and bilateral medullary thyroid carcinomas. A 9-year-old child harboring the gene mutation was diagnosed with medullary thyroid carcinoma. Surgical resection of the tumors was performed. All family members were advised to undergo complete genetic testing related to the C634Y mutation, and the corresponding treatments administered based on test results and associated clinical guidelines., Conclusion: Advancements in MEN2A research are important for familial management, assessment of medullary thyroid cancer invasive risk, and deciding surgical timing., Competing Interests: Conflict-of-interest statement: The authors declare that they have no conflict of interest to disclose., (©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.)

Background: Cutaneous lichen amyloidosis (CLA) has been reported in some multiple endocrine neoplasia type 2A (MEN 2A) families affected by specific germline RET mutations C634F/G/R/W/Y or V804M, as a characteristic of the clinical manifestation in ‘MEN 2A with CLA’, one of four variants of MEN 2A, which was strictly located in the scapular region of the upper back. Patient Findings: This study reports a large south-eastern Chinese pedigree with 17 individuals carrying the MEN 2A-harboring germline C611Y (c.1832G>A) RET mutation by Sanger sequencing. One individual presented MEN 2A-related clinical features, including typical CLA in the interscapular region; another individual exhibited neurological pruritus and scratching in the upper back but lacked CLA skin lesions. Both subjects presented with CLA or pruritic symptoms several years before the onset of medullary thyroid carcinoma (MTC) and/or pheochromocytoma. The remaining 15 RET mutation carriers did not exhibit CLA; of these, one presented with MTC and pheochromocytoma, nine with MTC only, two with elevated serum calcitonin and three younger subjects with normal serum calcitonin levels. This family’s clinical data revealed a later diagnosis of MTC (mean age, 45.9 (range: 23–73) years), a lower penetrance of pheochromocytoma (2/17, 11.8%) and CLA (1/17, 5.9%). However, no hyperparathyroidism and Hirschsprung disease were reported in this family. Summary and Conclusions: This is the first description of a family with MEN 2A-related CLA due to a germline RET C611Y mutation, which might exhibit a novel and diversified genotype–phenotype spectrum in MEN 2A.

Background: Malignant pheochromocytoma is a rare neuroendocrine tumor that may metastasize to the bones, liver, lungs, kidneys, and lymph nodes. Cerebral and skull metastases are even rarer, with only 17 cases reported in the literature. To the best of the authors' knowledge, this is the first reported case of a purely calvarial metastasis from malignant pheochromocytoma associated with multiple endocrine neoplasia type 2A (MEN2A). Case Description: A 31-year-old Filipino man diagnosed with MEN2A was found to have elevated urine metanephrine on routine surveillance, and workup revealed right adrenal and hepatic masses and a focus of intense tracer accumulation on the right frontal bone on metaiodobenzylguanidine I-123 scan. All the newly discovered lesions were resected to achieve tumor control. Histopathology revealed a diagnosis of pheochromocytoma for the calvarial lesion. Conclusion: Malignant pheochromocytoma may give rise to indolent metastatic foci that can easily be missed without a thorough examination. Misdiagnosis and delays in management of this disease can be detrimental, resulting in irreversible complications and death. [ABSTRACT FROM AUTHOR]

Background: Multiple endocrine neoplasia type 2A (MEN2A) is a rare, hereditary syndrome resulting from a germline mutation in the RET proto-oncogene and characterized primarily by medullary thyroid cancer (MTC), pheochromocytoma (PHEO), and hyperparathyroidism. Types of RET mutation have been associated with age at onset, clinical outcomes of MTC, and the penetrance of other components. Patients classified as ‘high-risk’ by the American Thyroid Association (ATA), based on the aggressiveness of MTC and the penetrance of other components, are recommended to undergo early prophylactic thyroidectomy at age ≤ 5 years and to be screened for PHEO at age ≥ 11 years. Patients with RET codon C634R mutations have been classified as high-risk. Case presentation: The present study describes a 71-year-old woman newly diagnosed with hereditary MTC related to a RET C634R germline mutation. Her basal serum calcitonin level was high, but there was no evidence of distant metastases. Surgery revealed bilateral MTC with two metastatic lymph nodes. Because microscopic resection was incomplete and extranodal extension was observed, the patient underwent adjuvant external beam radiotherapy. Response to therapy was excellent. Follow-up after 1.5 years showed no evidence of disease or other manifestations of MEN2A. Conclusion: Despite RET C634R carriers being classified as high-risk by the ATA, this patient did not present with either distant MTC or PHEO until her seventies. To our knowledge, only one other patient has shown a similar late identification of a RET C634R mutation, but MTC could not be diagnosed because the patient was lost to follow-up. Further research is required to develop optimal protocols that could allow patients requiring prophylactic thyroidectomy to be differentiated from those who can be monitored closely without early surgery.

Background: Routine preoperative assessment of the tumor marker calcitonin for medullary thyroid cancer (MTC) and the generally improved diagnostics with high-resolution ultrasound, elastography and Doppler function as well as functional imaging, enable the earlier detection of organ-limited, non-metastasized MTC. Thereby, a new treatment option arises for surgical de-escalation in sporadic MTC, moving from routine thyroidectomy with bilateral central lymph node dissection towards unilateral thyroidectomy with ipsilateral central lymph node dissection., Material and Methods: A search was carried out in PubMed for surgical approaches and selection of publications with results from limited resection in sporadic MTC., Results: In selected patient cohorts limited resection surgery can achieve adequate oncological results but requires long-term follow-up., Discussion: When sporadic unifocal primary tumors are identified and intraoperative frozen section pathological investigation is consistently employed for assessing the grade of desmoplasia and breach of the tumor capsule, the extent of resection can be intraoperatively adapted. Pivotal prerequisites for this personalized concept include consideration of preoperative clinical criteria and intraoperative surgical assessment in conjunction with the intraoperative frozen section examination in order to achieve an adequate oncological tumor resection and a biochemical cure., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

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Background: Inherited medullary thyroid carcinoma (MTC) is primarily caused by RET mutations that are commonly localized in exons 5, 8, 10, 11, and 13–16. In this study, we report pedigrees for individuals with MTC that harbor a germline S409Y variant within exon 6 of the RET proto-oncogene. Methods: Targeted sequencing was used to diagnose four apparently sporadic MTC index cases carrying the germline RET S409Y (c.1226 C>A) variant. Subsequently, 27 relatives of these individuals underwent clinical and genetic assessments and/or thyroid surgery. Furthermore, in silico analyses and in vitro assays were performed to predict or verify the potential oncogenic activity of the S409Y variant. Results: Overall, 15 of 31 participants were found to carry the RET S409Y variant. Of these, 6 presented with isolated MTC (mean age 50.2 years; range 41–75 years), of which 3 presented with neck lymph node metastases and 2 presented with distant liver or lung metastases. Among the remaining 9 carriers, 3 (mean age 56 years; range 41–76 years) had elevated serum calcium-stimulated calcitonin (sCtn) or concurrent marginally elevated serum calcitonin (Ctn) levels, whereas the other 6 (mean age 37.5 years; range 14–52 years) exhibited typical Ctn/sCtn levels (p < 0.05). None of the 15 carriers in these 4 families presented clinical evidence of pheochromocytoma, hyperparathyroidism, or Hirschsprung's disease. In silico analyses revealed that S409Y was a "possibly damaging" mutation that could affect the RET protein inter-domain interface. An in vitro assay revealed that the phosphorylation level of RET tyrosine 905 was relatively higher in the RET S409Y mutant than in wild-type (WT) RET. Moreover, transfection of HEK 293 cells with S409Y enhanced the phosphorylation activity of AKT, ERK pathways, and it increased cell proliferation compared with WT RET, but to a lesser degree than that for the RET C618Y and C634Y mutations. Conclusions: This study demonstrates that the novel germline RET S409Y variant is likely pathogenic and is associated with lower penetrance of MTC than that for the C618Y and C634Y mutations. Individuals with S409Y should be managed using a personalized approach, and additionally, "at-risk" family members should be evaluated. Additional studies are needed to elucidate the correlation between the S409Y mutation and multiple endocrine neoplasia type 2-specific tumors. [ABSTRACT FROM AUTHOR]

Introduction: Multiple endocrine neoplasia 2A (MEN 2A) is an inherited dominant syndrome due to specific RET proto-oncogene mutations characterised by medullary thyroid carcinoma (MTC), adrenal pheochromocytoma and hyperparathyroidism. Molecular genetic diagnostics are currently allowing familial types of MTC to be detected at an asymptomatic stage and surgery thus to be performed at a time when the prognosis is good. The current report aims to highlight the importance of appropriate monitoring of patients with hereditary MEN 2A syndrome as well as the importance of reasonable timing for prophylactic thyroidectomy in a paediatric patient with MTC. Case Report: We present the case of a 5-year-old male patient with a family history of MEN2A syndrome and metabolic syndrome who was admitted to our department for excessive weight gain and hypertension. Physical examination revealed an overweight patient (96.4th BMI percentile), cervical and axillary acanthosis nigricans and arterial hypertension (BP>95th percentile). Biochemical investigations revealed elevated basal and post-calcium stimulation test calcitonin levels, normal serum, and 24h-urine metanephrines levels and normal PTH levels. Thyroid ultrasound described a marked hypoechogenic area with an ill-defined margin and slightly visible intranodular vascularisation but no calcifications. 18F-FDOPA PET/CT did not describe local or distant metastases. Findings were overall consistent with MTC and the patient underwent total thyroidectomy. Histopathological examination confirmed the diagnosis of in situ MTC. Postoperatively the patient received long-term thyroid replacement therapy and the follow-up included thyroid ultrasound evaluation of residual disease, calcitonin and thyroglobulin levels, fractionated metanephrines and PTH every 6 months. DNA analysis of our patient and his brother, who had no endocrinopathies, confirmed the diagnosis of MEN2A by a mutation at codon 634 of the RET proto-oncogene. Discussions : Nearly all patients with MEN2A have either C-cell hyperplasia (CCH) or MTC, but the incidence of these manifestations depends on the underlying RET mutation. Even though our patient was not tested for RET gene mutations preoperatively, the MEN2A family history, high calcitonin levels and imaging findings were considered sufficient for the surgical indication. Even though thyroidectomy is associated with a higher morbidity rate in pediatric patients, in this case, it was necessary to prevent macro-invasive MTC, lymph node involvement and distance metastases. Conclusions: MTC is the most common cause of death in MEN2A patients, its early diagnosis through regular screenings and the optimal timing for prophylactic thyroidectomy are crucial. Genotype-phenotype correlation in MEN2A familial syndromes has a strong variability even in patients with the same mutation. [ABSTRACT FROM AUTHOR]

Resumen El feocromocitoma constituye una neoplasia productora de catecolaminas que se presenta de forma esporádica o asociada a enfermedades de transmisión hereditaria, como la neoplasia endocrina múltiple. Los síntomas clásicos como la cefalea, sudoración y palpitaciones son atribuidos a la actividad del sistema nervioso simpático y suelen presentarse en forma de paroxismos. La tuberculosis pulmonar es una enfermedad infecciosa que constituye un problema de salud pública en muchos países, cuya incidencia depende de algunos factores incluyendo la inmunosupresión que generan las enfermedades endocrino-tumorales como la antes descrita. Presentamos el caso de un paciente masculino de 38 años que acude a emergencia por presentar un paroxismo de hipertensión arterial y dolor abdominal, como manifestaciones iniciales de un feocromocitoma en el contexto de una neoplasia endocrina múltiple de tipo IIA. El paciente desarrolló de forma concomitante tuberculosis pulmonar; no obstante, se logró tratar ambas entidades consiguiendo una evolución clínica favorable.