Germline RET Research Articles

ODP450 A Case of Metastatic Medullary Thyroid Cancer Presenting with Pathologic Hip Fracture

Abstract Introduction Medullary thyroid cancer accounts for less than 5% of thyroid malignancies. Distant metastatic disease typically presents in lymph nodes, lung, liver and bone. We present a patient who initially presented with a pathologic hip fracture with bone biopsy revealing medullary thyroid carcinoma. Case Description A 44-year-old male with no past medical history presented to the emergency department for right hip pain following a mechanical fall. Imaging showed a right femoral neck pathologic fracture as well as lytic lesions within the right femoral neck and right ilium. Family history was significant for pancreatic cancer and breast cancer. The patient underwent bone biopsy of the right femur followed by total hip arthroplasty. Bone biopsy revealed metastatic medullary thyroid carcinoma. Thyroid ultrasound showed a 1.2 centimeter right solid hypoechoic nodule along with extensive cervical lymphadenopathy. Further imaging revealed metastatic disease throughout the thoracic spine, mediastinal lymphadenopathy, and a left 2.2 centimeter adrenal lesion with peripheral enhancement and possible necrosis. Carcinoembryonic antigen (CEA) level was 551 ng/mL (normal <4.7), calcitonin was 2,498 pg/mL (normal <10), and calcium levels were normal. Plasma free metanephrines were normal and plasma normetanephrines were less than two times the upper limit of normal. Genetic testing on the bone biopsy specimen revealed a RET p. C618S variant. Germline RET testing was collected. The patient was discharged with close follow-up with oncology to initiate systemic therapy and follow-up with endocrinology for the adrenal mass. Discussion Majority of cases of medullary thyroid carcinoma are sporadic. Patients typically present with a thyroid nodule with many having cervical lymph node involvement at diagnosis and 5-10% having distant metastatic disease. Our patient's initial presentation was unique in that he presented with a pathologic fracture. Bone metastases can be seen in about 30% of cases of metastatic medullary thyroid carcinoma. Calcitonin levels greater than 500 pg/mL require additional imaging to exclude metastatic disease. If RET mutational status is unknown, patients should be screened for primary hyperparathyroidism and pheochromocytoma. Screening for pheochromocytoma is critical in preoperative management of these patients. Treatment for patients with metastatic disease involves surgery, external beam radiotherapy, and kinase inhibitors. Presentation: No date and time listed

RF33 | PSUN04 Luteinizing Hormone-Chorionic Gonadotrophin Receptor in Pheochromocytomas

Abstract Background Pheochromocytomas and paragangliomas (PPGL) are catecholamine-producing neuroendocrine tumors that arise from the adrenal medulla or ganglia and display the highest heritability rate among all human tumours. Genomic analyses allowed identification of molecular subgroups of PPGL which are organized into 2 main clusters. Cluster 1 contains SDHx- and VHL-mutated tumors which do not produce epinephrine while cluster 2 includes the epinephrine-secreting PPGL related to RET, NF1, TMEM127 and MAX mutations. PPGL must be early diagnosed and treated to prevent adrenergic crises which can be life-threatening. Detection of PPGL is particularly important during pregnancy since PPGL are associated with a high risk of either maternal or fetal complications in this context. Reciprocally, pregnancy can favor adrenergic crises in patients with previously undiagnosed or silent pheochromocytoma (PCC). These dangerous events can be triggered by tumor compression resulting from fetus growth, or labor and delivery. However, it is known that surges in plasma catecholamines may also occur during early gestation suggesting that pregnancy may also activate the secretory activity of PPGL through the involvement of non-mechanical factors, such as gestational hormones. Methods In the present study, we report a case of silent PCC revealed in a pregnant woman by life-threatening adrenergic myocarditis occurring at 31 weeks of gestation. Analysis of PPGL susceptibility genes showed the presence of a heterozygous germline RET variant of uncertain significance. The fact that the first symptoms of catecholamine excess had appeared during the first trimester of pregnancy led us to conduct in vitro studies to investigate the effects of estradiol and the pregnancy hormone chorionic gonadotropin (hCG) on epinephrine secretion by cultured cells derived from the resected patient's tumor. Expression of luteinizing hormone/chorionic gonadotropin receptor (LHCGR) was searched for in the tumor and an additional series of 12 PCC by RT-qPCR and immunohistochemistry. LHCGR expression was also analyzed in silico in the PPGL cohorts of the COMETE and The Cancer Genome Atlas (TCGA) databases. Results hCG stimulated epinephrine secretion by primary cultured PCC cells. The tumor expressed the LHCG receptor, which was colocalized with catecholamine-producing enzymes. A similar expression pattern of the LHCG receptor was also observed in 5 out of a series of 12 PCCs. Moreover, in silico studies revealed that PPGL display the highest expression levels of LHCGR mRNA among the 32 solid tumor types of TCGA cohort. Interestingly, expression of LHCGR was higher in cluster 2 than in cluster 1 PPGL. Conclusion We show that PCC can express functional LHCG receptor. Consequently, pregnancy may activate catecholamine production by previously silent pheochromocytoma as early as the first trimester of gestation especially in women with gene mutations that predispose to cluster 2 epinephrine-secreting PCC. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m., Monday, June 13, 2022 1:18 p.m. - 1:23 p.m.

Clinical and genetic analysis of seven Chinese pedigrees affected with multiple endocrine neoplasia type 2A with cutaneous lichen amyloidosis

To explore the pathological characteristics and significance of RET proto-oncogene screening in multiple endocrine neoplasia type 2A (MEN2A) with cutaneous lichen amyloidosis (CLA). Clinical data of 51 members from 7 unrelated pedigrees of MEN2A-CLA were collected. Systemic clinical investigations including biochemical testing, imaging examination, germline RET variant screening and histopathological examination were carried out. RET gene variants were detected in 28 patients with MEN2A (C634G/F/R/S/W and C611Y) including 12 males and 16 females, with the mean age of diagnosis being (41.1 ± 18.3) years old, which were consistent with their clinical manifestations. The incidence of medullary thyroid carcinoma (MTC), pheochromocytoma (PHEO), hyperparathyroidism (HPTH) and CLA among 28 MEN2A patients were 89.3%, 28.6%, 7.1% and 28.6%, respectively. Comparison of the incidence of MTC/PHEO/HPTH and CLA between C611Y and C634G/F/R/S/W, only PHEO and CLA in C611Y were lower than those in C634G/F/R/S/W (P < 0.05; P < 0.05). Among 8 patients with CLA, the male to female ratio was 2 : 6. The clinical features included pruritus in the interscapular region and presence of dry, thickened, scaly, brown pigment, clustered or desquamate-like plaques. The mean onset age of CLA [(18.4 ± 4.6) years] versus the mean age at diagnosis of CLA or MEN2A were significantly different (P < 0.001; P < 0.001). MEN2A-CLA may be the early clinical manifestation of MEN2A and most frequently occurred along with RET-C634 variant. To facilitate the recognition of MEN2A-CLA, to combine family investigation and screening of RET variant are helpful for early diagnosis and standardized treatment, which can improve the long-term outcome of MEN2A-specific tumors.

Extensive patient-to-patient single nucleus transcriptome heterogeneity in pheochromocytomas and paragangliomas.

Pheochromocytoma, neuroendocrine tumor, single cell RNA-sequencing, transcriptome, heterogeneity, SDHB, RET, paraganglinoma; Pheochromocytomas (PC) and paragangliomas (PG) are rare neuroendocrine tumors with varied genetic makeup and are associated with high cardiovascular morbidity and a variable risk of malignancy. The source of the transcriptional heterogeneity of the disease and the underlying biological processes that determine the outcome of PCPG remain largely unclear. We focused on PCPG tumors with germline SDHB and RET mutations, which represent distinct prognostic groups with worse or better prognoses, respectively. We applied single-nuclei RNA sequencing (snRNA-seq) to tissue samples from 11 patients and found high patient-to-patient transcriptome heterogeneity in neuroendocrine tumor cells. The tumor microenvironment also showed heterogeneous profiles, mainly contributed by macrophages of the immune cell clusters and Schwann cells of the stroma. By performing non-negative matrix factorization, we identified common transcriptional programs active in RET and SDHB, as well as distinct modules, including neuronal development, hormone synthesis and secretion, and DNA replication. Similarities between the transcriptomes of the tumor cells and those of the chromaffin- and precursor cell types suggests different developmental stages at which PC and PG tumors appear to be arrested.

Metastatic medullary thyroid carcinoma: a new way forward.

Medullary thyroid carcinoma (MTC) is a rare malignancy comprising 1–2% of all thyroid cancers in the United States. Approximately 20% of cases are familial, secondary to a germline RET mutation, while the remaining 80% are sporadic and also harbour a somatic RET mutation in more than half of all cases. Up to 15–20% of patients will present with distant metastatic disease, and retrospective series report a 10-year survival of 10–40% from time of first metastasis. Historically, systemic therapies for metastatic MTC have been limited, and cytotoxic chemotherapy has demonstrated poor objective response rates. However, in the last decade, targeted therapies, particularly multitargeted tyrosine kinase inhibitors (TKIs), have demonstrated prolonged progression-free survival in advanced and progressive MTC. Both cabozantinib and vandetanib have been approved as first-line treatment options in many countries; nevertheless, their use is limited by high toxicity rates and dose reductions are often necessary. New generation TKIs, such as selpercatinib or pralsetinib, that exhibit selective activity against RET, have recently been approved as a second-line treatment option, and they exhibit a more favourable side-effect profile. Peptide receptor radionuclide therapy or immune checkpoint inhibitors may also constitute potential therapeutic options in specific clinical settings. In this review, we aim to present all current therapeutic options available for patients with progressive MTC, as well as new or as yet experimental treatments.

Surgical aspects and controversies in the management of medullary thyroid cancer.

Medullary thyroid cancer (MTC) accounts for only 4% of thyroid carcinomas but 15% of thyroid cancer deaths. MTC is a tumour of the calcitonin secreting parafollicular C cells in the thyroid which can occur sporadically or be hereditary in multiple endocrine neoplasias type 2 syndromes due to germline RET mutations. Sporadic forms of MTC can also be caused by mutations in the RET protooncogene. MTC commonly presents in a late stage, with 70% of patients presenting with local nodal metastasis. Currently, the only curative treatment for MTC is surgical removal. The aim of this paper is to describe the current guidelines and progressions of the surgical management of MTC and to highlight up-and-coming chemotherapies. A database literature review was completed utilizing PubMed to cumulate the extant literature, screening for most recent guidelines and publications regarding the management of MTC. Current guidelines were described by the American Thyroid Association in 2015. Controversial publications continue to present supporting evidence for varying degrees of thyroidectomy and neck dissections. Recently, researchers have been exploring non-surgical options including external beam radiotherapy and multikinase inhibitors such as vandetanib and cabozantinib for the treatment of MTC. Surgical management of MTC remains controversial and varies significantly dependent on the extent of disease. Chemotherapeutic options have undetermined effects on survival to date.

GLOBAL ENDOCRINOLOGY: Geographical variation in the profile of RET variants in patients with medullary thyroid cancer: a comprehensive review.

Genetic variability in humans is influenced by many factors, such as natural selection, mutations, genetic drift, and migrations. Molecular epidemiology evaluates the contribution of genetic risk factors in the etiology, diagnosis, and prevention of a particular disease. Few areas of medicine have been so clearly affected by genetic diagnosis and management as multiple neoplasia type 2 (MEN2), in which activating pathogenic variants in the RET gene results in the development of medullary thyroid carcinoma (MTC), pheochromocytoma, and hyperparathyroidism in nearly 98, 50, and 25% of gene carriers, respectively. Here, we aimed to collect RET genotyping data worldwide to analyze the distribution and frequency of RET variants from a global perspective. We show that the mutational spectrum of RET is observed worldwide. The codon 634 variants seem to be the most prevalent, but there are differences in the type of amino acid exchanges among countries and in the frequencies of the other RET codon variants. Most interestingly, studies using haplotype analysis or pedigree linkage have demonstrated that some pathogenic RET variants have been transmitted to offspring for centuries, explaining some local prevalence due to a founder effect. Unfortunately, after almost three decades after the causative role of the germline RET variants has been reported in hereditary MTC, comprehensive genotyping data remain limited to a few countries. The heterogeneity of RET variants justifies the need for a global effort to describe epidemiological data of families with MEN2 to further understand the genetic background and environmental circumstances that affect disease presentation.

Active Surveillance in RET Gene Carriers Belonging to Families with Multiple Endocrine Neoplasia.

Simple SummaryMEN2 has a very high penetrance for the development of medullary thyroid cancer. However, intra- and inter-familial variabilities have been described. Accordingly, in this precision medicine era, a personalized approach should be adopted in subjects harboring RET mutations. In these subjects, we showed that thyroid surgery could be safely timed according to basal and stimulated calcitonin, especially in children who can reach adulthood, avoiding the risks of thyroid surgery and decreasing the period of a long-life hypothyroidism treatment.Multiple Endocrine Neoplasia 2 (MEN2) is a hereditary cancer syndrome for developing medullary thyroid cancer (MTC) due to germline mutations of RET gene. Subjects harboring a germline RET mutation without any clinical signs of MTC are defined as gene carriers (GCs), for whom guidelines propose a prophylactic thyroid surgery. We evaluate if active surveillance of GCs, pursuing early thyroid surgery, can be safely proposed and if it allows safely delaying thyroid surgery in children until adolescence/adulthood. We prospectively followed 189 GCs with moderate or high risk germline RET mutation. Surgery was planned in case of: elevated basal calcitonin (bCT) and/or stimulated CT (sCT); surgery preference of subjects (or parents, if subject less than 18 years old); other reasons for thyroid surgery. Accordingly, at RET screening, we sub-grouped GCs in subjects who promptly were submitted to thyroid surgery (Group A, n = 67) and who were not (Group B, n = 122). Group B was further sub-grouped in subjects who were submitted to surgery during their active surveillance (Group B1, n = 22) and who are still in follow-up (Group B2, n = 100). Group A subjects presented significantly more advanced age, bCT and sCT compared to Group B. Mutation RETV804M was the most common variant in both groups but it was significantly less frequent in Group A than B. Analyzing age, bCT, sCT and genetic landscape, Group B1 subjects differed from Group B2 only for sCT at last evaluation. Group A subjects presented more frequently MTC foci than Group B1. Moreover, Group A MTCs presented more aggressive features (size, T and N) than Group B1. Accordingly, at the end of follow-up, all Group B1 subjects presented clinical remission, while 6 and 12 Group A MTC patients had structural and biochemical persistent disease, respectively. Thank to active surveillance, only 13/63 subjects younger than 18 years at RET screening have been operated on during childhood and/or adolescence. In Group B1, three patients, while actively surveilled, had the possibility to reach the age of 18 (or older) and two patients the age of 15, before being submitted to thyroid surgery. In Group B2, 12 patients become older than 18 years and 17 older than 15 years. In conclusion, we demonstrated that an active surveillance pursuing an early thyroid surgery could be safely recommended in GCs. This patient-centered approach permits postponing thyroid surgery in children until their adolescence/adulthood. At the same time, we confirmed that genetic screening allows finding hidden MTC cases that otherwise would be diagnosed much later.

Clinical Activity of Selpercatinib in RET Mutant Pheochromocytoma-Case Reports

Activating RET gene alterations have been reported in solid tumors including the rare cancer, pheochromocytoma (PHEO) found sporadically and in familial multiple endocrine neoplasia type 2 (MEN2) syndromes. Selpercatinib is a highly selective and potent small molecule RET kinase inhibitor that has demonstrated marked and durable anti-tumor activity in diverse RET-altered solid tumors. Described are the initial 3 PHEO patients treated with selpercatinib (LIBRETTO-001/NCT03157128). Case 1: 70-year-old white male with MEN2A and a history of medullary thyroid cancer (MTC) and PHEO s/p thyroidectomy and adrenalectomy, received MIBG in 1991 and 2016 due to symptom reoccurrence. Progressive metastatic disease associated with severe hypertension was treated with Lutate in 2017 and germline RET mutation p.Cys634Phe was confirmed. After developing severe back pain due to a T6 vertebral metastasis, he began selpercatinib treatment. As of Mar 2020, he has a partial response (PR) as assessed by investigator; his back pain resolved, normetanephrine and metanephrine levels decreased, and has ceased alpha and beta blockers. He remains on treatment with only grade 1-2 adverse events, none requiring interruption or dose modification. Case 2: 51-year-old white female with MEN2A and history of MTC and PHEO s/p thyroidectomy and adrenalectomy in 2010. She developed metastatic PHEO in 2013, with multiple bone, omentum, lung, liver, and spleen metastases. Between 2013 and 2018 she was treated with multiple courses of radiation and, additional surgical resections; a PR with sunitinib lasted 13 months followed by temozolomide/capecitabine treatment. A bone lesion biopsy in 2018 confirmed RET C618S mutation and with her disease progression and uncontrolled bone pain, she began selpercatinib treatment, experiencing a PR. After 5.5 months in the study, she discontinued treatment due to disease progression. Case 3: 45-year-old African American female diagnosed with sporadic PHEO in 1996, s/p multiple surgical resections. She received 2 cycles of cyclophosphamide/vincristine/dacarbazine without clinical benefit. I-131-MIBG therapy with autologous stem cell rescue in 2017 improved blood pressure, palpitations, and flushing but without tumor shrinkage while abdominal pain persisted. Somatic M918T RET-mutation was confirmed, and she began selpercatinib treatment in 2018 with symptom resolution and improved plasma metanephrine levels. She required dose reduction for grade 3 palmar-plantar erthrodysesthesia and had stable disease for 22 months until a new bone metastasis was identified. Due to ongoing clinical benefit, she remains on treatment despite disease progression. Conclusion: These are the initial reports of RET-mutant PHEO patients treated with selpercatinib adding to the diversity of RET-altered tumor types that may benefit from a selective RET inhibitor.

A Case of Paraneoplastic Erythropoietin Secretion Secondary to Medullary Thyroid Cancer

Background: Paraneoplastic erythropoietin (EPO) secretion is a well-described phenomenon that is classically seen in renal cell carcinoma. It has also been described in parathyroid adenoma and in pheochromocytoma. Additionally, follicular thyroid cancer cells, papillary thyroid cancer cells, and anaplastic thyroid cancer cells have all been found to express EPO in vitro. To our knowledge, EPO expression by medullary thyroid cancer has not previously been studied. Here, we describe a case of suspected paraneoplastic EPO secretion in the setting of advanced medullary thyroid cancer.Clinical Case: A 46 year-old woman presented to our clinic with hoarseness and was proven to have a medullary thyroid cancer with enlarged lymph nodes on the right at levels IV, V and VI. Genetic testing was negative for a germline RET mutation. She underwent total thyroidectomy with bilateral lymph node dissection and was subsequently treated with external beam radiation therapy. Pathology confirmed the diagnosis of medullary thyroid cancer, with extension beyond the thyroid capsule and bilateral lymph node involvement. Rising calcitonin and CEA were noted over the following years. A MRI of the abdomen showed indeterminate subcentimetric liver lesions. A Gallium-68 Dotatate PET scan confirmed the suspicion of liver metastases. Five years after the initial surgery, the patient developed rising hemoglobin levels, despite a long-standing history of iron deficiency anemia. JAK2 testing was negative. EPO levels were elevated (43.45 mU/mL, reference range 2.59 - 18.5 mU/mL) suggesting secondary polycythemia. The patient had a negative smoking history and a pulse oximetry of 98%; there was no evidence of hypoxia that could cause an elevation in EPO. Other differential diagnoses including pheochromocytoma, Cushing’s syndrome from ectopic ACTH production, and renal and brain tumors were excluded. Biopsy of the liver lesions is not technically feasible at this time. Since discovery of the erythrocytosis, the patient has undergone repeated therapeutic phlebotomies, to maintain acceptable hematocrit levels.Conclusion: We believe that our patient’s case may be the first reported case of ectopic EPO production from medullary thyroid cancer causing polycythemia. We encourage other clinicians to report similar clinical cases in order to better understand this rare clinical entity.

Occurrence of Hepatocellular Carcinoma in a 40-Year-Old Male With MEN2A Syndrome

Background: Multiple Endocrine Neoplasia Type 2A (MEN 2A) is a genetic syndrome in which the patient is susceptible to the development of: 1. medullary thyroid carcinoma, 2. pheochromocytoma, and 3. parathyroid adenomas or hyperplasia. Our objective is to report the first occurrence of hepatocellular carcinoma in a young adult male with MEN 2A syndrome without prior liver disease.Clinical Case: A 40-year-old male was screened positive for the C634R point mutation of the RET Proto-Oncogene after his sister with MEN 2A syndrome had tested positive. The patient had no history of alcohol or drug abuse. His family history was remarkable for the deaths of his mother and maternal grandmother from unknown malignancies at the ages of 35 and 45 respectively. His physical exam revealed a BP of 135/85mm Hg, BMI 26 kg/m2 and palpable bilateral thyroid nodules. Lab tests included a calcitonin of 131 pg/ml, (0.0-8.4 pg/ml), calcium 11.4 mg/dL (8.4-10.3 mg/dL), parathyroid hormone (PTH) 1765 pg/ml (12-65 pg/ml), ALK PHOS 1856 U/L (20-120 U/L), ALT 16 U/L (<39 U/L), Albumin 4.1gm/dl (3.4-5.0gm/dl), plasma normetanephrine 0.95 nmol/L (0.00- 0.89 nmol L) and urine metanephrines 291 pg/d (62-207 pg/d). A CT scan demonstrated hyperdense 12 mm right and 5 mm left adrenal nodules, both confirmed MIBG positive. Neck ultrasound showed bilateral thyroid nodules, the largest measuring 1.1 x 0.8 x 1.1 cm in the right lobe and a 3.5 x 2.2 x 2.1 cm heterogeneous mass posterior to the right thyroid lobe. The patient was prepped with doxazosin and underwent a laparoscopic right adrenalectomy then 2 months later a total thyroidectomy with neck lymph node dissection, resection of the right parathyroid tumor mass and bilateral inferior parathyroid glands. Surgical pathology confirmed the right adrenal pheochromocytoma, multifocal bilateral medullary thyroid cancer with 1 of 70 neck lymph nodes positive and a single large parathyroid adenoma. He received levothyroxine to maintain euthyroidism. Within 6 months of his surgery, calcitonin was < 2 pg/ml, CEA 2.3 U/ml (<5.0 U/ml) and ALK PHOS 44 U/L. Urine metanephrines remained mildly elevated 291 pg/d (62-207 pg/d). Serial abdominal CT imaging revealed no change of the left adrenal mass but three new bi-lobar 1-2 cm enhancing liver lesions. CT guided needle biopsies of the liver masses revealed hepatocellular cancer without evidence of cirrhosis. The patient underwent successful thermal ablation of all 3 liver lesions. Laboratory evaluation was negative for Hepatitis A, B and C. His alpha fetal protein level has remained stable in the range of 4.7 to 5.8 ng/ml (<15ng/ml).Conclusions: This is the first reported case of hepatocellular carcinoma in a patient with MEN 2A syndrome who had no predisposing liver disease, raising suspicion that his germline RET mutation contributed to his liver cancer.

Zebra Case of Papillary Thyroid Cancer in MEN-2 Syndrome

Introduction: The occurrence of papillary thyroid cancer in patients with familial medullary thyroid cancer (FMTC) is extremely rare and underreported. Case Presentation: A 51-year-old caucasian female with no past medical history who presented to primary care physician for her annual visit. She denied any complaints. Vital signs were unremarkable. Physical examination was remarkable for large left thyroid nodule without cervical lymph nodes enlargements. Family history was significant for metastatic MTC of her two sisters (at the age of 55, 60) and her niece at age of 21. She previously declined genetic testing. Labs were unremarkable including serum calcium of 8.3 mg/dL. Thyroid function panel revealed a TSH of 2.1 μU/mL, Free T4 of 1.4 ng/dL, Thyroid peroxidase (TPO) antibody of <6 IU/mL. Neck ultrasonography revealed a mid-left thyroid hypoechoic nodule of 1.8 ×1.5 cm, without cervical lymph nodes enlargements. Fine needle biopsy revealed a papillary thyroid cancer, follicular variant. The diagnosis confirmed by two university pathologists, without any evidence of MTC. Genetic testing revealed a germline mutation in RET oncogene exons 13. Further labs revealed normal metanephrines of 12 pg/mL and normal normetanephrine of 31 pg/mL, normal serum calcitonin was less than 2 pg/mL (0-5), normal serum CEA was 2.5 ng/mL (0-5), elevated anti- thyroglobulin (anti-TG) antibodies of 1234 iu/mL (0-0.9), and elevated thyroglobulin of 50 ng/mL (1.5-38.5). The patient was referred to ENT for total thyroidectomy. Further, she was treated with radioactive iodine ablation by 155 mCi of iodine 131. Follow up whole body thyroid scan revealed no evidence of residual or recurrence. The patient was treated with 112 mcg levothyroxine with a target of TSH less than 0.1. On six months follow up, repeated neck ultrasonography revealed no remnant of thyroid tissue. Follow up Thyroglobulin (TG) was less than 0.1 ng/mL, TSH 0.05 μU/mL, FT4 of 1.98 ng/dL, and calcitonin was still less than 2 pg/ml. Genetic testing of her daughters (24, 31) revealed germline mutations in RET-oncogene exons 13 and was referred for prophylactic thyroidectomy. Discussion: FMTC is an inherited syndrome characterized by the presence of only MTC without hyperparathyroidism or pheochromocytoma and is considered a variant of MEN2A. Most cases of MEN2A have been attributed to mutations in the intracellular portion of RET, and somatic mutations in RET have been identified in 50% of cases of sporadic FMTC. We recommend in patients with germline RET mutations and a family history of MTC, the diagnosis of papillary thyroid cancer should be confirmed by two pathologists, and patients should be tested for serum calcitonin, serum calcium, and metanephrines/normetanephrine levels. Genetic testing of first-degree relatives of FMTC at an early age is essential in guiding major management decisions such as the timing of prophylactic thyroidectomy.

Spectrum of Germline RET variants identified by targeted sequencing and associated Multiple Endocrine Neoplasia type 2 susceptibility in China

BackgroundGermline RET mutations and variants are involved in development of multiple endocrine neoplasia type 2 (MEN2). The present study investigated a spectrum of RET variants, analyzed genotype-phenotype relationships, and evaluated their effect on the MEN2 phenotype in Han Chinese patients.MethodsTargeted sequencing detected germline RET variants in 697 individuals, including 245 MEN2, 120 sporadic medullary thyroid cancer (MTC), and 15 pheochromocytoma (PHEO) patients and their 493 relatives. In silico analyses and classifications following ACMG-2015 were performed. Demographic, clinical variant types, and endocrine neoplasia molecular diagnosis records were also analyzed.ResultsNineteen different RET mutations (18 point and 1 del/ins mutations) in 214 patients with MEN2A (97.7%) or MEN2B (2.3%) were found, of which exon 11/10 mutations accounted for 79% (169/214). Nineteen compound mutations were found in 31 patients with MEN2A. Twenty-three variants (18 single and 5 double base substitution/compound variants) non-classification were also found. Of these, 17 (3 of pathogenic, 10 of uncertain significance, 2 of likely benign and 2 as benign) were found in 31 patients with MTC/PHEO. The remaining 6 variants (4 of uncertain significance and 2 of likely benign) found in 8 carriers had no evidence of MEN2. The entire cohort showed MEN2A-related PHEO, all occurring in exons 11/10, particularly at C634. Kaplan-Meier curves showed age-dependent penetration rates of MTC and PHEO, and occurrence rates of PHEO in patients with exon 11 mutations were all higher than those within exon 10; these bilateral PHEO were always associated with exon 11 mutations (all P < 0.05). While patient offspring had PHEO, parents with MEN2A had none, the frequency was approximately 10%. Interestingly, at least 6.8% of families were adoptive. Also, 3 non-hotspot RET variants (R114H, T278N, and D489N) appeared with high frequency. Conversely, polymorphism S836S was absent.ConclusionsThese data are largely consistent with current evidence-based recommendations in the clinical practice guidelines. Diversity of RET variants or carriers may involve a different natural disease course. Further large-scale targeted sequencing studies will serve as an accurate and cost-effective approach to investigating MEN2 genotype-phenotype correlations for discovery of rare or unknown variants of RET.

Genetic and clinical aspects of paediatric pheochromocytomas and paragangliomas.

Few and conflicting reports have characterized the genetics of paediatric pheochromocytomas and paragangliomas (PPGLs). This study aimed to investigate the clinical and genetic features of Brazilian children with PPGL. This study included 25 children (52% girls) with PPGL. The median age at diagnosis was 15years (4-19). The median time of follow-up was 145months. The genetic investigation was performed by Sanger DNA sequencing, multiplex ligation-dependent probe amplification and/or target next-generation sequencing panel. Of the 25 children with PPGL, 11 (44%), 4 (16%), 2 (8%), 1 (4%) and 7 (28%) had germline VHL pathogenic variants, SDHB, SDHD, RET and negative genetic investigation, respectively. Children with germline VHL missense pathogenic variants were younger than those with SDHB or SDHD genetic defects [median (range), 12 (4-16) vs. 15.5 (14-19)years; P=.027]. Moreover, 10 of 11 cases with VHL pathogenic variants had bilateral pheochromocytoma (six asynchronous and four synchronous). All children with germline SDHB pathogenic variants presented with abdominal paraganglioma (one of them malignant). The two cases with SDHD pathogenic variants presented with head and neck paraganglioma. Among the cases without a genetic diagnosis, 6 and 2 had pheochromocytoma and paraganglioma, respectively. Furthermore, metastatic PPGL was diagnosed in four (16%) of 25 PPGL. Most of the paediatric PPGL were hereditary and multifocal. The majority of the affected genes belong to pseudohypoxic cluster 1, with VHL being the most frequently mutated. Therefore, our findings impact surgical management and surveillance of children with PPGL.

Functional impact of a germline RET mutation in alveolar rhabdomyosarcoma.

Specific mutations in the RET proto-oncogene are associated with multiple endocrine neoplasia type 2A, a hereditary syndrome characterized by tumorigenesis in multiple glandular elements. In rare instances, MEN2A-associated germline RET mutations have also occurred with non-MEN2A associated cancers. One such germline mutant RET mutation occurred concomitantly in a young adult diagnosed with alveolar rhabdomyosarcoma, a pediatric and young adult soft-tissue cancer with a generally poor prognosis. Although tumor tissue samples were initially unable to provide a viable cell culture for study, tumor tissues were sequenced for molecular characteristics. Through a hierarchical clustering approach, the index case sample was matched to several genetically similar cell models, which were transformed to express the same mutant RET as the index case and used to explore potential therapeutic options for mutant RET-bearing alveolar rhabdomyosarcoma. We also determined whether the RET mutation associated with the index case caused synthetic lethality to select clinical agents. From our investigation, we did not identify synthetic lethality associated with the expression of that patient's RET variant, and overall we did not find experimental evidence for the role of RET in rhabdomyosarcoma progression.

Pheochromocytoma in Multiple Endocrine Neoplasia Type 2

This pheochromocytoma is from an adrenal gland of an individual with multiple endocrine neoplasia type 2. What statement is most accurate regarding pheochromocytoma in multiple endocrine neoplasia type 2?a.Pheochromocytomas in the setting of multiple endocrine neoplasia type 2 are almost always single and unilateralb.Pheochromocytoma associated with multiple endocrine neoplasia type 2 is often associated with diffuse medullary hyperplasia or small nodulesc.Pheochromocytoma is almost always the presenting feature in multiple endocrine neoplasia type 2, occurring decades before medullary thyroid carcinomad.In the setting of multiple endocrine neoplasia type 2, pheochromocytomas are usually very aggressive with a high mortality rate due to metastatic pheochromocytoma Answer: b. Pheochromocytoma associated with multiple endocrine neoplasia type 2 is often associated with diffuse medullary hyperplasia or small nodules Pheochromocytoma occurs in approximately 50% of cases of multiple endocrine neoplasia type 2. In this setting, it generally presents about a decade after medullary thyroid carcinoma.1Raue F. Frank-Raue K. Genotype-phenotype correlation in multiple endocrine neoplasia type 2.Clinics (Sao Paulo). 2012; 67: 69-75Crossref PubMed Scopus (49) Google Scholar In multiple endocrine neoplasia type 2, the underlying genetic abnormality is germline RET mutation. Overall, pheochromocytomas and paragangliomas in adults are associated with an underlying pathogenic germline abnormality in approximately 40% of cases.2Turchini J. Cheung V.K.Y. Tischler A.S. et al.Pathology and genetics of phaeochromocytoma and paraganglioma.Histopathology. 2018; 72: 97-105Crossref PubMed Scopus (54) Google Scholar Hereditary paragangliomas and pheochromocytomas are not limited to multiple endocrine neoplasia type 2, as they can occur with other syndromes and germline genetic abnormalities such as in von Hippel-Lindau, neurofibromatosis type 1, and succinate dehydrogenase subunit-related tumors, as well as in those associated with underlying abnormalities of TMEM127, FH, MAX, and other genes. Hereditary and sporadic pheochromocytomas and paragangliomas may be histologically similar, however, in multiple endocrine neoplasia type 2 the tumors can be multiple or single and may be associated with diffuse or nodular (micro-pheochromocytomas) adrenal medullary hyperplasia as well as hyaline globules (see figure).3Webb T.A. Sheps S.G. Carney J.A. Differences between sporadic pheochromocytoma and pheochromocytoma in multiple endocrime neoplasia, type 2.Am J Surg Pathol. 1980; 4: 121-126Crossref PubMed Scopus (56) Google Scholar,4Gosset P. Lecomte-Houcke M. Duhamel A. et al.112 cases of sporadic and genetically determined pheochromocytoma: a comparative pathologic study.Ann Pathol. 1999; 19: 480-486PubMed Google Scholar

Genomics and Epigenomics of Medullary Thyroid Carcinoma: From Sporadic Disease to Familial Manifestations.

Our understanding of the genomics and epigenomics of medullary thyroid carcinoma (MTC) has advanced since the initial recognition of RET as a driver of MTC tumorigenesis in familial MTC. We now have insight into the frequency and prognostic significance of specific RET mutations in sporadic MTC. For example, the most common RET mutation in sporadic MTC is the RET Met918Thr mutation, the same mutation that underlies MEN2B and a poor prognosticator. This mutation is relatively infrequent in medullary thyroidmicrocarcinomas but is over-represented in advanced-stage disease. RAS mutations are detected in 70% of sporadic, RET wild-type MTC. Although next-generation and whole-exome sequencing studies have shown that tumors that are wild-type for RET and RAS mutations essentially lack other recurrent mutations, additional pathways and epigenetic alterations have been implicated in MTC tumorigenesis. Increased insight into the clinical course of patients with familial MTC with specific RET mutations has guided treatment recommendations for these patients. Finally, an understanding of the genomics has informed treatment for patients with advanced MTC. In this review, we will examine the genomics and epigenomics of sporadic and familial MTC, along with the prognostic significance of molecular alterations, management of patients with germline RET mutations, and treatment strategies for MTC patients.

Diagnostic RET genetic testing in 1,058 index patients: A UK centre perspective.

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. Retrospective case-note review. 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. The rate and nature of pathogenic variant detection were recorded, as well as the indication for testing. 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. 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.

Molecular Characterization Reveals the Importance and Diversity of Germline and Somatic RET Mutations in Cancer

Molecular Characterization Reveals the Importance and Diversity of Germline and Somatic RET Mutations in Cancer

Elevated basal serum levels of calcitonin and simultaneous surgery of MEN2A-specific tumors.

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.