Osteoporosis in multiple endocrine neoplasia type 1: severity, clinical significance, relationship to primary hyperparathyroidism, and response to parathyroidectomy

Importance of early detection in multiple endocrine neoplasia type 1: Clinical insights and future directions

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal-inherited syndrome involving multiple endocrine tumors. It is characterized by multiple mutations in the tumor suppressor gene MEN1, which is located on chromosome 11q13. As main etiology of MEN1 is genetic mutations, clinical symptoms may vary. In this editorial, we comment on the article by Yuan et al. This article describes a case of (MEN1) characterized by low incidence and diagnostic complexity. MEN1 commonly presents as parathyroid, pancreatic, and pituitary tumors. Diagnosis requires a combination of serologic tests, magnetic resonance imaging, computed tomography, endoscopic ultrasonography, immunologic and pathology. The diagnosis is unique depending on the site of disease. Surgical resection is the treatment of choice for MEN1. The prognosis depends on the site of origin, but early detection and intervention is the most effective.

Management of primary hyperparathyroidism in MEN1: From initial subtotal surgery to complex treatment of the remaining gland

Multiple endocrine neoplasia type 1 (MEN1) is a rare genetic disease with autosomal dominant transmission, which can cause various tumors, particularly endocrine, in a given patient. Primary hyperparathyroidism (PHPT) is the most common and earliest manifestation, leading to surgery before the age of 50 in most patients. Biological severity and renal and/or bone complications dictate the timing of parathyroid surgery. The objective is to correct hypercalcemia to prevent impact, while minimizing the risk of hypoparathyroidism. The most widely recommended procedure is subtotal parathyroidectomy (3 or 3.5 glands removed), with thymic horn resection via a cervical route. The development of imaging techniques, however, makes it possible to discuss partial surgery (resection of 1 or 2 glands) on a case-by-case basis depending on preoperative imaging and other elements such as patient age. Finally, hypercalcemia recurrence after initial surgery is a common feature of MEN1, and management of the remaining gland is challenging with various options: reoperation, calcimimetics and US-guided ablation or therapeutic abstention.

Bone mineral density over ten years after primary parathyroidectomy in multiple endocrine neoplasia type 1

Primary hyperparathyroidism (PHPT) associated with multiple endocrine neoplasia type 1 (MEN1) impairs bone mineral density and causes osteoporosis already in young patients. We aimed to investigate bone mineral density (BMD) in a contemporary cohort of patients with MEN1-related PHPT after long-term follow-up and compare these results with that of healthy controls. Thirty-five patients with genetically confirmed MEN1 were diagnosed with MEN1 at mean age 28.7 ± 13.6 years. Thirty-two (91.4%) underwent primary parathyroidectomy at mean age 33.3 ± 13.7 years; 12 had undergone at least 2 surgeries with on average 7.3 ± 5.9 years between the operations. BMD was assessed by DXA at the end of mean follow-up, 13.2 years after the primary parathyroidectomy and compared with that of 35 age- and gender-matched controls. More than 10 years after the first parathyroidectomy, mean BMD in patients with MEN1 is in the normal range. However, it is still significantly lower compared with healthy controls.

Analysis of Bone Phenotype Differences in MEN1-Related and Sporadic Primary Hyperparathyroidism Using 3D-DXA

Background: The rarity and variability of MEN1-related primary hyperparathyroidism (mPHPT) has led to contradictory data regarding the bone phenotype in this patient population. Methods: A single-center retrospective study was conducted among young age- and sex-matched patients with mPHPT and sporadic hyperparathyroidism (sPHPT). The main parameters of calcium-phosphorus metabolism, bone remodeling markers, and bone mineral density (BMD) measurements were obtained during the active phase of hyperparathyroidism before parathyroidectomy (PTE) and 1 year after. Trabecular Bone Score (TBS) and 3D-DXA analysis of the proximal femur were used to evaluate the differences in bone architecture disruption between groups. Results: Patients with mPHPT had significant lower preoperative BMD compared to sPHPT at lumbar spine-LS (p = 0.002); femur neck-FN (p = 0.001); and total hip-TH (p = 0.002). 3D-DXA analysis showed the prevalence of cortical rather than trabecular bone damage in mPHPT compared to sPHPT: cortical thickness (p < 0.001); cortical surface BMD (p = 0.001); cortical volumetric BMD (p = 0.007); and trabecular volumetric BMD (p = 0.029). One year after, PTE DXA and 3D-DXA parameters were similar between groups, while 3D-visualisation showed more extensive regeneration in cortical sBMD and cortical thickness in mPHPT. Conclusions: mPHPT is associated with lower preoperative BMD values with predominant architecture disruption in the cortical bone. The absence of differences in DXA and 3D-DXA parameters 1 year after PTE between mPHPT/sPHPT combined with significantly lower BMD in mPHPT at the initial stage may indicate faster bone recovery after surgery in mPHPT than in sPHPT.

Multiple Endocrine Neoplasia Type 1, Type 2A, and Type 2B

Multiple endocrine neoplasia type 1 is a rare genetic neuroendocrine syndrome caused by over 1500 different germline mutations. It can cause 20 different endocrine tumors affecting primarily the parathyroid glands, gastroenteropancreatic tract, and the anterior pituitary gland. Multiple endocrine neoplasia type 2A (MEN2A) and Multiple endocrine neoplasia type 2B (MEN2B) are autosomal dominant genetic syndromes because of a germline variant in the 'rearranged during transfection' (RET) proto-oncogene. There are common RET mutations causing receptor hyperactivation and induction of downstream signals that cause oncogenesis. Common conditions with MEN2A are medullary thyroid cancer (MTC), pheochromocytoma, and primary hyperparathyroidism. Common conditions with MEN2B include MTC, pheochromocytomas, and benign ganglioneuromas.

Role of Nutrition in the Management of Patients with Multiple Endocrine Neoplasia Type 1

Multiple endocrine neoplasia type 1 (MEN1) is a rare syndrome caused by inactivating mutations in the MEN1 tumor suppressor gene. The three main clinical manifestations of MEN1 are primary hyperparathyroidism (PHPT), duodenal-pancreatic neuroendocrine tumors (DP-NETs) and anterior pituitary tumors. Endocrine tumors in patients with MEN1 differ from sporadic tumors because of their younger age at onset, common multiple presentations and the different clinical course. MEN1 is characterized by a complex clinical phenotype; thus, patients should be followed by a multidisciplinary team of experts that includes an endocrinologist, a surgeon, a oncologist, a radiotherapist, and not least, a nutritionist. It is important to remember the fundamental role that diet plays as a primary prevention tool, together with a healthy and active lifestyle in preventing osteoporosis/osteopenia and reducing the risk of developing kidney stones due to hypercalciuria, two frequent clinical complications in MEN1 patients. Is very important for MEN1 patients to have an adequate intake of calcium, vitamin D, magnesium and phosphate to maintain good bone health. The intake of foods containing oxalates must also be kept under control because in combination with calcium they concur to form calcium oxalate crystals, increasing the risk of nephrolithiasis. Another aspect to consider is the management of patients with pancreatic neuroendocrine tumors undergoing major surgical resections of the pancreas that can lead to alterations in digestion and absorption mechanisms due to partial or total reduction in pancreatic enzymes such as amylase, lipase, and protease, resulting in malabsorption and malnutrition. Therefore, the nutritionist's aim should be to devise a dietary plan that takes into consideration each single patient, educating them about a healthy and active lifestyle, and accompanying them through various life stages by implementing strategies that can enhance their quality of life.

Effects of short- and long-term TSH suppression on lumbar bone mineral density in both genders using PET/CT

Iatrogenic subclinical hyperthyroidism is induced intentionally in patients with differentiated thyroid cancer to reduce the risk of tumor recurrence. This retrospective study aimed to investigate the effect of thyroid-stimulating hormone (TSH) suppressive therapy on bone mineral density in men and women. Two cohorts of endocrine cancer patients were compared. In cohort A, 42 patients with long-lasting suppressed serum TSH were assessed. Cohort B consisted of 41 euthyroid patients. Bone density was measured in the L1-L4 lumbar vertebrae of all patients using PET/CT scans performed for cancer staging. In 17 patients of cohort A who received a second PET/CT scan, bone density was measured again to provide longitudinal analysis. A non-significant difference in age (p = .572) and equal distribution of sex (p = .916) was determined when comparing both cohorts. A significant difference (p = .011) with a moderate effect (η2 = .08; 20.4%) was observed regarding higher bone mineral density (BMD^HU) in cohort B with normal TSH levels (M 160.63 ± 54.7 HU) versus cohort A under TSH suppression therapy (M 127.9 ± 59.5 HU) for a mean duration of 4.45 ± 2.64 years. Furthermore, no significant change in BMD^HU (p = .786) was found in those patients who received a second PET/CT scan after a mean observation time of 2.3 ± 1.2 years. In conclusion, long-lasting TSH suppression therapy caused a statistically significant decrease in BMD^HU while short-lasting therapy didn't. Therefore, we can assume a higher likelihood of osteoporosis in those patients under prolonged TSH suppression.

Clinical profile and treatment outcomes among patients with sporadic and multiple endocrine neoplasia syndrome-related primary hyperparathyroidism

OBJECTIVE

Accurate demarcation between multiple endocrine neoplasia, type 1 (MEN1)- related primary hyperparathyroidism (MPHPT) and sporadic PHPT (SPHPT) is important to plan the management of primary parathyroid disease and surveillance for other endocrine and nonendocrine tumours. The objective of this study is to compare the clinical, biochemical and radiological features and surgical outcomes in patients with MPHPT versus SPHPT and to identify the predictors of MEN1 syndrome in PHPT.

DESIGN, PATIENTS AND MEASUREMENTS

This was an ambispective observationalstudy involving 251 patients with SPHPT and 23 patients with MPHPT evaluated at the endocrine clinic of All India Institute of Medical Sciences, New Delhi, India between January 2015 and December 2021.

RESULTS

The prevalence of MEN1 syndrome among patients with PHPT was 8.2% and a genetic mutation was identified by Sanger sequencing in 26.1% of patients with MPHPT. Patients with MPHPT were younger (p < .001), had lower mean serum calcium (p = .01) and alkaline phosphatase (ALP; p = .03) levels and lower bone mineral density (BMD) Z score at lumbar spine (p < .001) and femoral neck (p = .007). The prevalence of renal stones (p = .03) and their complications (p = .006) was significantly higher in MPHPT group. On multivariable analysis, factors predictive of MPHPT were hyperplasia on histopathology [OR 40.1, p < .001], ALP levels within reference range [OR 5.6, p = .02] and lumbar spine BMD [OR 0.39 per unit increase in Z score, p < .001].

CONCLUSIONS

Patients with MPHPT have more severe, frequent and early onset of bone and renal involvement despite milder biochemical features. A normal serum ALP, low BMD for age and gender at lumbar spine and histopathology evidence of hyperplasia are predictive factors for MEN1 syndrome in PHPT.

Clinical and molecular features of four Brazilian families with multiple endocrine neoplasia type 1

Objective

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant syndrome characterized by its clinical variability and complexity in diagnosis and treatment. We performed both clinical and molecular descriptions of four families with MEN1 in a follow-up at a tertiary center in Brasília.

Methods

From a preliminary review of approximately 500 medical records of patients with pituitary neuroendocrine tumor (PitNET) from the database of the Neuroendocrinology Outpatient Clinic of the University Hospital of Brasília, a total of 135 patients met the criteria of at least two affected family members. From this cohort, we have identified 34 families: only four with a phenotype of MEN1 and the other 30 families with the phenotype of familial isolated pituitary adenoma (FIPA). Eleven patients with a clinical diagnosis of MEN1 from these four families were selected.

Results

Variants in MEN1 gene were identified in all families. One individual from each family underwent genetic testing using targeted high-throughput sequencing (HTS). All patients had primary hyperparathyroidism (PHPT), and the second most common manifestation was PitNET. One individual had well-differentiated liposarcoma, which has been previously reported in a single case of MEN1. Three variants previously described in the database and a novel variant in exon 2 have been found.

Conclusions

The study allowed the genotypic and phenotypic characterization of families with MEN1 in a follow-up at a tertiary center in Brasília.

Multilevel Annotation of Germline MEN1 Variants of Synonymous, Nonsynonymous, and Uncertain Significance in Indian Patients With Sporadic Primary Hyperparathyroidism

Primary hyperparathyroidism (PHPT) is third most common endocrine disorder characterized by hypercalcemia with elevated or nonsuppressed parathyroid hormone levels by parathyroid tumors. Familial PHPT, as part of multiple endocrine type-1, occurs due to the germline mutation in the MEN1 gene. The involvement and the role of germline MEN1 variations in sporadic PHPT of Indian PHPT patients are unknown. Precise classifications of different types of MEN1 variations are fundamental for determining clinical relevance and diagnostic role. This prospective cohort study was performed on 82 patients with PHPT (with no clinical or history of MEN1) who underwent screening for MEN1 variations through Sanger sequencing. Multilevel computational analysis was performed to determine the structure-function relationship of synonymous, nonsynonymous, and variants of uncertain significance (VUS). Of the 82 PHPT patients, 42 (51%) had 26 germline MEN1 variants, including eight nonsynonymous, seven synonymous, nine VUS, one splice site, and one regulatory variation. Five most common germline variations (c.1838A>G, c.1817C>T, c.1525C>A, c.-35A>T, and c.250T>C) were observed in this study. c.-35A>T (5' untranslated region [UTR]) was associated with recurrence of PHPT (odds ratio [OR] = 5.4; p = 0.04) and subsequent detection of other endocrine tumors (OR = 13.6, p = 0.035). c.1525C>A was associated with multi glandular parathyroid tumor (OR = 13.6, p = 0.035). Align-Grantham variation and Grantham deviation (Align-GVGD), functional analysis through hidden Markov MODEL (FATHMM), and MutationTaster analysis reported the disease-specific potential of VUS and synonymous variations. Significant linkage disequilibrium was observed in c.1785G>A and c.1817C>T (r²  = 0.3859, p = 0.0001), c.1475C>G and c.1525C>A (r²  = 0.385, p = 0.0004), and c.1569T>C and c.1838A>G (r²  = 0.488, p = 0.0001). The detection of MEN1 variations, especially those with disease-specific potential, can prompt early screening for other MEN1-related tumors and disease recurrence. © 2022 American Society for Bone and Mineral Research (ASBMR).

Update on the clinical management of multiple endocrine neoplasia type 1

This review provides an overview of novel insights in the clinical management of patients with Multiple Endocrine Neoplasia Type 1, focusing on the last decade since the last update of the MEN1 guidelines. With regard to Diagnosis: Mutation-negative patients with 2/3 main manifestations have a different clinical course compared to mutation-positive patients. As for primary hyperparathyroidism: subtotal parathyroidectomy is the initial procedure of choice. Current debate centres around the timing of initial parathyroidectomy as well as the controversial topic of unilateral clearance in young patients. For duodenopancreatic neuroendocrine tumours (NETs), the main challenge is accurate and individualized risk stratification to enable personalized surveillance and treatment. Thymus NETs remain one of the most aggressive MEN1-related tumours. Lung NETs are more frequent than previously thought, generally indolent, but rare aggressive cases do occur. Pituitary adenomas are most often prolactinomas and nonfunctioning microadenomas with an excellent prognosis and good response to therapy. Breast cancer is recognized as part of the MEN1 syndrome in women and periodical screening is advised. Clinically relevant manifestations are already seen at the paediatric age and initiating screening in the second decade is advisable. MEN1 has a significant impact on quality of life and US data show a significant financial burden. In conclusion, patient outcomes have improved, but much is still to be achieved. For care tailored to the needs of the individual patient and improving outcomes on an individual basis, studies are now needed to define predictors of tumour behaviour and effects of more individualized interventions.

Bone phenotypes in multiple endocrine neoplasia type 1: survey on the MEN1 Florentine database

Multiple endocrine neoplasia type 1 (MEN1) is a rare, inherited cancer syndrome characterized by the development of multiple endocrine and non-endocrine tumors. MEN1 patients show a reduction of bone mass and a higher prevalence of early onset osteoporosis, compared to healthy population of the same age, gender, and ethnicity. During the monitoring and follow-up of MEN1 patients, the attention of clinicians is primarily focused on the diagnosis and therapy of tumors, while the assessment of bone health and mineral metabolism is, in many cases, marginally considered. In this study, we retrospectively analyzed bone and mineral metabolism features in a series of MEN1 patients from the MEN1 Florentine database. Biochemical markers of bone and mineral metabolism and densitometric parameters of bone mass were retrieved from the database and were analyzed based on age ranges and genders of patients and presence/absence of the three main MEN1-related endocrine tumor types. Our evaluation confirmed that patients with a MEN1 diagnosis have a high prevalence of earlyonset osteopenia and osteoporosis, in association with levels of serum and urinary markers of bone turnover higher than the normal reference values, regardless of their different MEN1 tumors. Fifty percent of patients younger than 26 years manifested osteopenia and 8.3% had osteoporosis, in at least one of the measured bone sites. These data suggest the importance of including biochemical and instrumental monitoring of bone metabolism and bone mass in the routine medical evaluation and follow-up of MEN1 patients and MEN1 carriers as important clinical aspects in the management of the syndrome.

Genetic deletion of menin in mouse mesenchymal stem cells: an experimental and computational analysis

Loss‐of‐function mutations in the MEN1 tumor‐suppressor gene cause the multiple endocrine neoplasia type 1 syndrome. Menin, the MEN1 gene product, is expressed in many tissues, including bone, where its function remains elusive. We conditionally inactivated menin in mesenchymal stem cells (MSCs) using paired‐related homeobox 1 (Prx1)‐Cre and compared resultant skeletal phenotypes of Prx1‐Cre;Men1^f/f menin‐knockout mice (KO) and wild‐type controls using in vivo and in vitro experimental approaches and mechanics simulation. Dual‐energy X‐ray absorptiometry demonstrated significantly reduced bone mineral density, and 3‐dimensional micro‐CT imaging revealed a decrease in trabecular bone volume, altered trabecular structure, and an increase in trabecular separation in KO mice at 6 and 9 months of age. Numbers of osteoblasts were unaltered, and dynamic histomorphometry demonstrated unaltered bone formation; however, osteoclast number and activity and receptor activator of NF‐κB ligand/osteoprotegerin (RANKL/OPG) mRNA profiles were increased, supporting increased osteoclastogenesis and bone resorption. In vitro, proliferative capabilities of bone marrow stem cells and differentiation of osteoblasts and mineralization were unaltered; however, osteoclast generation was increased. Gross femur geometrical alterations observed included significant reductions in length and in mid‐metaphyseal cross‐sectional area. Atomic force microscopy demonstrated significant decreases in elasticity of both cortical and trabecular bone at the nanoscale, whereas three‐point bending tests demonstrated a 30% reduction in bone stiffness; finite element analysis showed morphological changes of the femur microgeometry and a significantly diminished femur flexural rigidity. The biomechanical results demonstrated the detrimental outcome of the accelerated osteoclastic bone resorption. Our studies have a twofold implication; first, MEN1 deletion from MSCs can negatively regulate bone mass and bone biomechanics, and second, the experimental and computational biomechanical analyses employed in the present study should be applicable for improved phenotypic characterization of murine bone. Furthermore, our findings of critical menin function in bone may underpin the more severe skeletal phenotype found in hyperparathyroidism associated with loss‐of‐function of the MEN1 gene. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

[Severe bone complications of primary hyperparathyroidism in a young patient with the rare verified mutation of MEN1]

Multiple endocrine neoplasia type 1 syndrome (MEN1) is a rare inherited disorder that can include combinations of more than 20 endocrine and non-endocrine tumors. Unfortunately, none of the described MEN1 mutations has been associated with a peculiar clinical phenotype, even within members of the same family, thus a genotype-to-phenotype correlation does not exist. MEN1 syndrome is the most common cause of hereditary primary hyperparathyroidism (PHPT), the disease penetrance of which exceeds 50% by the age of 20 and reaches 95% by the age of 40. At the same time, PHPT with hyperplasia or adenomas of the parathyroid glands (PTG) is the most distinctive manifestation of the MEN1 syndrome. One of the main symptoms of PHPT, both in sporadic and hereditary forms of the disease, is bone damage. At the time of diagnosis in PHPT/MEN1, the bone mineral density is generally lower in comparison with the sporadic form of PHPT. This may be due to excessive secretion of parathyroid hormone during the period of peak bone mass, concomitant components of the syndrome, extended surgical treatment, and the direct effect of a mutation in the menin gene on bone remodeling. This clinical case describes a young patient with severe bone complications of PHPT and uncertain rare MEN1 mutation. PHPT was diagnosed five years later from the first onset of bone complications and repeated orthopedic operations. There was the «hungry bones» syndrome after successful surgery of PHPT, which was managed with vitamin D and calcium carbonate supplementation and there is a positive dynamic in increased bone mineral density in the main skeleton after 6 months.

Multiple Endocrine Neoplasia in Childhood: An Update on Diagnosis, Screening, Management and Treatment

Multiple endocrine neoplasia (MEN) is a group of heterogenous syndromes characterized by the occurrence of two or more endocrine gland tumors in a patient or related individuals in the same family. They are inherited in an autosomal dominant fashion and are highly penetrant. There are three types of MEN syndromes: MEN type 1 (MEN1), MEN type 2 (MEN2), and MEN type 4 (MEN4). MEN2 is further divided into MEN2A, MEN2B (formerly known MEN3), and familial medullary thyroid carcinoma (FMTC). Although MEN syndromes are rare, it is crucial to identify individuals at risk for potentially life-threatening neoplasias. This review article provides an update on each MEN syndrome, its genetics, diagnosis, and management in children.

Genetic Determinants of Inherited Endocrine Tumors: Do They Have a Direct Role in Bone Metabolism Regulation and Osteoporosis?

Endocrine tumors are neoplasms originating from specialized hormone-secreting cells. They can develop as sporadic tumors, caused by somatic mutations, or in the context of familial Mendelian inherited diseases. Congenital forms, manifesting as syndromic or non-syndromic diseases, are caused by germinal heterozygote autosomal dominant mutations in oncogenes or tumor suppressor genes. The genetic defect leads to a loss of cell growth control in target endocrine tissues and to tumor development. In addition to the classical cancer manifestations, some affected patients can manifest alterations of bone and mineral metabolism, presenting both as pathognomonic and/or non-specific skeletal clinical features, which can be either secondary complications of endocrine functioning primary tumors and/or a direct consequence of the gene mutation. Here, we specifically review the current knowledge on possible direct roles of the genes that cause inherited endocrine tumors in the regulation of bone modeling and remodeling by exploring functional in vitro and in vivo studies highlighting how some of these genes participate in the regulation of molecular pathways involved in bone and mineral metabolism homeostasis, and by describing the potential direct effects of gene mutations on the development of skeletal and mineral metabolism clinical features in patients.

Bone and Mineral Metabolism Phenotypes in MEN1-Related and Sporadic Primary Hyperparathyroidism, before and after Parathyroidectomy

Primary hyperparathyroidism (PHPT) is the most common endocrinopathy in multiple endocrine neoplasia type 1 (MEN1). Persistent levels of increased parathyroid hormone (PTH) result in a higher incidence of osteopenia and osteoporosis compared to the general population. Surgical removal of hyper-functioning parathyroid tissue is the therapy of choice. This retrospective study evaluated the effect of parathyroidectomy (PTX) on bone metabolism and bone mass in two series of patients with MEN1 PHPT and sporadic PHPT (sPHPT) by comparing bone metabolism-related biochemical markers and bone mineral density (BMD) before and after surgery. Our data confirmed, in a higher number of cases than in previously published studies, the efficacy of PTX, not only to rapidly restore normal levels of PTH and calcium, but also to normalize biochemical parameters of bone resorption and bone formation, and to improve spine and femur bone mass, in both MEN1 PHPT and sPHPT. Evaluation of single-patient BMD changes after surgery indicates an individual variable bone mass improvement in a great majority of MEN1 PHPT patients. In MEN1 patients, PTX is strongly suggested in the presence of increased PTH and hypercalcemia to prevent/reduce the early-onset bone mass loss and grant, in young patients, the achievement of the bone mass peak; routine monitoring of bone metabolism and bone mass should start from adolescence. Therapy with anti-fracture drugs is indicated in MEN1 patients with BMD lower than the age-matched normal values.

New therapies for patients with multiple endocrine neoplasia type 1

In 1953, for the first time, Paul Wermer described a family presenting endocrine gland neoplasms over several generations. The transmission was autosomal dominant and the penetrance was high. Forty years later in 1997, the multiple endocrine neoplasia type 1 (MEN1) gene was sequenced, thus enabling diagnosis and early optimal treatment. Patients carrying the MEN1 gene present endocrine but also non-endocrine tumors. Parathyroid, pancreatic and pituitary impairment are the three main types of endocrine involvement. The present article details therapeutic management of hyperparathyroidism, neuroendocrine pancreatic tumors and pituitary adenomas in patients carrying the MEN1 gene. Significant therapeutic progress has in fact been made in the last few years. As concerns the parathyroid glands, screening of family members and regular monitoring of affected subjects now raise the question of early management of parathyroid lesions and optimal timing of parathyroid surgery. As concerns the duodenum-pancreas, proton-pump inhibitors are able to control gastrin-secreting syndrome, reducing mortality in MEN1 patients. Mortality in MEN1 patients is no longer mainly secondary to uncontrolled hormonal secretion but to metastatic (mainly pancreatic) disease progression. Tumor risk requires regular monitoring of morphological assessment, leading to iterative pancreatic surgery in a large number of patients. Finally, pituitary adenomas in MEN1 patients are traditionally described as aggressive, invasive and resistant to medical treatment. However, regular pituitary screening showed them to be in fact infra-centimetric and non-secreting in the majority of patients. Consequently, it is necessary to regularly monitor MEN1 patients, with regular clinical, biological and morphological work-up. Several studies showed that this regular monitoring impairs quality of life. Building a relationship of trust between patients and care provider is therefore essential. It enables the patient to be referred for psychological or psychiatric care in difficult times, providing long-term support and preventing any breakdown in continuity of care.

Clinical aspects of multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1) is a rare syndrome characterized by the co-occurrence of primary hyperparathyroidism, duodenopancreatic neuroendocrine tumours (NETs) and/or pituitary adenomas. MEN1 can predispose patients to other endocrine and non-endocrine tumours, such as cutaneous tumours, central nervous system tumours and breast cancer. Endocrine tumours in patients with MEN1 differ from sporadic tumours in that they have a younger age at onset, present as multiple tumours in the same organ and have a different clinical course. Therefore, patients with overt MEN1 and those who carry a MEN1 mutation should be offered tailored biochemical and imaging screening to detect tumours and evaluate their progression over time. Fortunately, over the past 10 years, knowledge about the clinical phenotype of these tumours has markedly progressed, thanks to the implementation of national registries, particularly in France and the Netherlands. This Review provides an update on the clinical management of MEN1-related tumours. Epidemiology, the clinical picture, diagnostic work-up and the main lines of treatment for MEN1-related tumours are summarized. Controversial therapeutic aspects and issues that still need to be addressed are also discussed. Moreover, special attention is given to MEN1 manifestations in children and adolescents.

Multiple endocrine neoplasia type 1 revealed by a hip pathologic fracture

Multiple endocrine neoplasia type 1 is a rare autosomal inherited syndrome that affects a variety of endocrine tissues such as the parathyroid, endocrine pancreas, and anterior pituitary. Osseous complications are often misdiagnosed. We presented a case of a 46-year-old woman with pathological fractures of the lower limb. She had a history of type 1 diabetes and galactorrhea. Laboratory examinations showed hypercalcemia and an increased level of parathyroid hormone related to hyperparathyroidism. Serum chromogranin A level was increased at 9369 ng/mL (N < 102). A somatostatin receptor scintigraphy (octreoscan) revealed pathological uptake in the gastric wall, later cave adenopathy, and liver. The diagnosis of multiple endocrine neoplasia type 1 was made based on radiological and histological findings. The patient underwent a subtotal parathyroidectomy associated with somatostatin analog treatment leading to significant improvement. A literature review was conducted by searching PubMed using these following terms: multiple endocrine neoplasia type 1, hyperparathyroidism, fracture, menin, osteoporosis. We emphasized bone involvement related to multiple endocrine neoplasia type 1 syndrome. This diagnosis should be considered when pathological fractures occur in young patients with a history of endocrine disorder. We highlighted the importance of imaging features in making the diagnosis of multiple endocrine neoplasia type 1. Early management of this disease is necessary. Treatment including parathyroidectomy and somatostatin analogs leads to bone preservation and functional improvement.

Bone tissue and mineral metabolism in hereditary endocrine tumors: clinical manifestations and genetic bases

Inherited endocrine tumors are neoplasms of endocrine cells, transmitted via autosomal dominant germinal mutations. They present in two different forms: non-syndromic (patient has a single affected endocrine organ during his/her lifetime) or syndromic forms (multiple tumors in endocrine and non-endocrine organs during his/her lifetime).In addition to their common tumoral manifestations, many of these diseases present clinical affection of bone tissues and/or mineral metabolism, both as secondary complications of primary tumors and as primary defects due to genetic mutation. To date, few studies have documented these bone complications, and there are no systematic reviews in this area.We present a revision of medical literature about skeletal and mineral metabolism affections in inherited endocrine tumor syndromes, and studies, in cells and animal models, investigating the direct role of some genes, whose mutations are responsible for the development of endocrine tumors, in the regulation of bone and mineral metabolism.

Parental Multiple Endocrine Neoplasia Type 1 (MEN 1) Is Associated with Increased Offspring Childhood Mortality

CONTEXT

Information regarding the impact of parental multiple endocrine neoplasia type 1 (MEN 1) on neonatal outcomes is limited to case reports.

OBJECTIVE

To determine the impact of parental MEN 1 on neonatal outcomes.

METHODS

Retrospective cohort analysis of the Tasman 1 MEN 1 kindred stratified by whether birth occurred before ("historical cohort") or after ("contemporary cohort") prospective screening commenced. The historical cohort included kindred members born between 1825 and 1984 (n = 341 children with a MEN 1 positive (MEN 1+) parent and n = 314 children with MEN 1 negative (MEN 1-) parents). The contemporary cohort included neonates (n = 52) of MEN 1+ women (n = 21) managed at a tertiary referral hospital between 1985 and 2018.

RESULTS

Historical cohort: compared with MEN 1- parents, children of MEN 1+ parents were more likely to die postpartum (HR 4.6, P = .046 at 6 months of age). Excess mortality at 15 years of age was observed for children of MEN 1+ mothers (HR 8.50, P = .002) and fathers (HR 3.82, P = .03). Contemporary cohort: neonates of MEN 1+ mothers were more likely to have low birth weight (28.9% vs 6.7%, P = .01), be admitted to a higher care nursery (40.4% vs 17%, P = .02), and require a longer median postnatal stay (5 vs 4 days, P = .009) than the Australian average. Isolated antenatal hypercalcemia did not significantly alter neonatal outcomes.

CONCLUSION

Children with a MEN 1+ parent are disproportionately vulnerable postpartum. Neonates of MEN 1+ mothers remain vulnerable despite contemporary care. The excess risk was not fully explained by maternal MEN 1 or antenatal hypercalcemia.

MEN1-associated primary hyperparathyroidism in the Spanish Registry: clinical characterictics and surgical outcomes

Primary hyperparathyroidism is the most frequent manifestation of multiple endocrine neoplasia type 1 (MEN1) syndrome. Bone and renal complications are common. Surgery is the treatment of choice, but the best timing for surgery is controversial and predictors of persistence and recurrence are not well known. Our study describes the clinical characteristics and the surgical outcomes, after surgery and in the long term, of the patients with MEN1 and primary hyperparathyroidism included in the Spanish Registry of Multiple Endocrine Neoplasia, Pheochromocytomas and Paragangliomas (REGMEN). Eighty-nine patients (49 men and 40 women, 34.2 ± 13 years old) were included. Sixty-four out of the 89 underwent surgery: a total parathyroidectomy was done in 13 patients, a subtotal parathyroidectomy in 34 and a less than subtotal parathyroidectomy in 15. Remission rates were higher after a total or a subtotal parathyroidectomy than after a less than subtotal (3/4 and 20/22 vs 7/12, P < 0.05), without significant differences in permanent hypoparathyroidism (1/5, 9/23 and 0/11, N.S.). After a median follow-up of 111 months, 20 of the 41 operated patients with long-term follow-up had persistent or recurrent hyperparathyroidism. We did not find differences in disease-free survival rates between different techniques, patients with or without permanent hypoparathyroidism and patients with different mutated exons, but a second surgery was more frequent after a less than subtotal parathyroidectomy.

No evidence of adverse fertility and pregnancy outcomes in patients with unrecognized and untreated multiple endocrine neoplasia type 1

OBJECTIVE

Literature concerning the impact of multiple endocrine neoplasia type 1 (MEN 1) on fertility is limited to case reports despite the early onset of endocrinopathies, such as primary hyperparathyroidism and prolactinoma, that may impact fertility. This study describes the impact of unrecognized and untreated MEN 1 on fertility and pregnancy outcomes in a multigenerational cohort of the Tasman 1 MEN 1 kindred.

METHODS

All MEN 1 positive (MEN 1⁺ , n = 63) and MEN 1 negative (MEN 1^- , n = 75) descendants born between 1825 and 1951 of a common founder. Review of birth, death, marriage and medical records provided data on date of birth and death, gender, MEN 1 status and the number of pregnancies and children per parent.

RESULTS

Compared to MEN 1^- parents, MEN 1⁺ parents had more children (RR 1.30, 1.02-1.66) and live births (RR 1.31, 1.02-1.67) with no excess of stillbirths (RR 1.24, 0.24-6.36). Compared to the era-matched Tasmanian fertility rate, MEN 1⁺ parents had more children (4.87 ± 4.11 vs 3.40 ± 0.61, P = 0.048), whereas MEN 1^- parents had similar numbers of children (3.67 ± 3.27 vs 3.36 ± 0.62, P = 0.55). MEN 1⁺ parents had a similar number of MEN 1⁺ and MEN 1^- offspring (2.1 ± 1.9 vs 2.5 ± 2.3, P = 0.31). Indirectly assessed miscarriage rate was similar between MEN 1⁺ and MEN 1^- mothers (P = 0.77). Clinically overt pituitary disease reduced MEN 1⁺ kindred member likelihood of parenthood (33% vs 97%).

CONCLUSIONS

There was no adverse impact of MEN 1 on patient fertility overall; however, MEN 1-related pathology may have impaired the reproductive potential of a subset of individuals with pituitary disease.

Multiple Endocrine Neoplasia Type 1 (MEN1): An Update and the Significance of Early Genetic and Clinical Diagnosis

Multiple endocrine neoplasia type 1 (MEN1) is a rare hereditary tumor syndrome inherited in an autosomal dominant manner and characterized by a predisposition to a multitude of endocrine neoplasms primarily of parathyroid, enteropancreatic, and anterior pituitary origin, as well as nonendocrine neoplasms. Other endocrine tumors in MEN1 include foregut carcinoid tumors, adrenocortical tumors, and rarely pheochromocytoma. Nonendocrine manifestations include meningiomas and ependymomas, lipomas, angiofibromas, collagenomas, and leiomyomas. MEN1 is caused by inactivating mutations of the tumor suppressor gene MEN1 which encodes the protein menin. This syndrome can affect all age groups, with 17% of patients developing MEN1-associated tumors before 21 years of age. Despite advances in the diagnosis and treatment of MEN1-associated tumors, patients with MEN1 continue to have decreased life expectancy primarily due to malignant neuroendocrine tumors. The most recent clinical practice guidelines for MEN1, published in 2012, highlight the need for early genetic and clinical diagnosis of MEN1 and recommend an intensive surveillance approach for both patients with this syndrome and asymptomatic carriers starting at the age of 5 years with the goal of timely detection and management of MEN1-associated neoplasms and ultimately decreased disease-specific morbidity and mortality. Unfortunately, there is no clear genotype-phenotype correlation and individual mutation-dependent surveillance is not possible currently.

Primary hyperparathyroidism associated with MEN 1: Experience in 71 cases

INTRODUCTION

Primary hyperparathyroidism (pHPT) in MEN 1 is characterized by multiglandular disease and early involvement of parathyroid glands at different times. Persistence and recurrence range from 25%-35%. The purpose was: a) to describe the experience and the treatment of patients with pHPT in MEN 1; b) to analyze the variables related with clinical presentation and recurrence.

METHOD

A total of 97 patients with MEN 1 were diagnosed in a tertiary hospital. A retrospective analysis was made in patients with pHPT (n=71).

STUDY VARIABLES

age at diagnosis, mutation, clinical presentation, laboratory tests, surgical technique, and recurrence of HPT.

RESULTS

Mean age was 38 years, and 50 patients were asymptomatic. The surgical technique was: subtotal parathyroidectomy (n=55), resection of three glands (n=7), and resection of less glands (n=9). Transcervical thymectomy was performed in 53 patients. Mean follow-up was 102.9 months. There were 21 recurrences, There were correlations between age at diagnosis and serum calcium levels with the presence of symptoms (P<.0001). There were also correlations between recurrence and surgical technique (P<.03), non-association with thymectomy (P<.0001), and follow-up time (P<.03).

CONCLUSION

Performing genetic and clinical screening allows us to make a diagnosis in the asymptomatic period and to provide early treatment for HPT in MEN 1. The recurrence rate is high, and follow-up time and the surgical technique used are risk factors for recurrence.

The Importance of an Early and Accurate MEN1 Diagnosis

Multiple Endocrine Neoplasia type 1 (MEN1) is a rare autosomal dominant inherited condition, causing significant morbidity, and a reduction of life expectancy. A timely and accurate diagnosis of MEN1 is paramount to improve disease outcomes. This enables early identification of tumor manifestations allowing timely treatment for reducing morbidity and improving survival. Current management of MEN1 poses two challenges regarding the MEN1 diagnosis: diagnostic delay and the issue of phenocopies. A delay in diagnosis can be caused by a delay in identifying the index case, and by a delay in identifying affected family members of an index case. At present, lag time between diagnosis of MEN1 in index cases and genetic testing of family members was estimated to be 3.5 years. A subsequent delay in diagnosing affected family members was demonstrated to cause potential harm. Non-index cases have been found to develop clinically relevant tumor manifestations during the lag times. Centralized care, monitoring of patients outcomes on a national level and thereby improving awareness of physicians treating MEN1 patients, will contribute to improved care. The second challenge relates to "phenocopies." Phenocopies refers to the 5-25% of clinically diagnosed patients with MEN1in whom no mutation can be found. Up to now, the clinical diagnosis of MEN1 is defined as the simultaneous presence of at least two of the three characteristic tumors (pituitary, parathyroids, or pancreatic islets). These clinically diagnosed patients undergo intensive follow up. Recent insights, however, challenge the validity of this clinical criterion. The most common mutation-negative MEN1 phenotype is the combination of primary hyperparathyroidism and a pituitary adenoma. This phenotype might also be caused by mutations in the CDKN1B gene, causing the recently described MEN4 syndrome. Moreover, primary hyperparathyroidism and pituitary adenoma are relatively common in the general population. Limiting follow-up in patients with a sporadic co-occurrence of pHPT and PIT could reduce exposure to radiation from imaging, healthcare costs and anxiety.

When Parathyroidectomy Should Be Indicated or Postponed in Adolescents With MEN1-Related Primary Hyperparathyroidism

Multiple Endocrine Neoplasia Type 1 (MEN1) is a rare inherited endocrine tumor syndrome principally affecting parathyroid glands, neuroendocrine tissues of the gastro-entero-pancreatic and thoracic tracts, and anterior pituitary, caused by germline inactivating mutations of the MEN1 tumor suppressor gene. Primary hyperparathyroidism (PHPT) is usually the first clinical manifestation of the syndrome, normally manifesting during the third decade of life. Cases of affected children and adolescents have been described by the age of 5. Clinical characteristics and therapeutic management of MEN1 in adolescents have been described mainly by case reports. Only two studies on MEN1 patient series under the age of 22 years have recently been published. Given the scarcity of data and the lack of a consistent number of targeted studies, there are currently no specific guidelines available for children and adolescents with MEN1; diagnostic and therapeutic management is, thus, usually the same as for adult patients. Here, we report our experience with 19 adolescent MEN1 patients, developing MEN1-associated PHPT before the age of 20. Fourteen of them, manifesting hypercalcemic PHPT before the age of 20 underwent parathyroidectomy before the age of 25 to control calcemia. Parathyroid surgery restored normal calcemia in all the operated patients. No post-surgical nephrolithiasis has been reported after a mean of 12.0 ± 5.8 years of follow-up. Comparison between pre-surgical and post-surgical values of bone mineral density (BMD) in 2 patients evidenced an improvement of bone mass after parathyroid adenoma ablation. Two patients (14.28%) developed permanent post-surgical hypoparathyroidism.

Intraoperative Decision-Making and Technical Aspects of Parathyroidectomy in Young Patients With MEN1 Related Hyperparathyroidism

One in 5,000 to 1 in 50,000 births have multiple endocrine neoplasia type 1 (MEN1). MEN1 is a hereditary syndrome clinically defined by the presence of two of the following endocrine tumors in the same patient: parathyroid adenomas, entero-pancreatic endocrine tumors and pituitary tumors. Most commonly, patients with MEN1 manifest primarily with signs and symptoms linked to primary hyperparathyroidism. By age 50, it is estimated that 100% of patients with MEN1 will have been diagnosed with primary hyperparathyroidism. These patients will need to undergo resection of their hyperfunctioning glands, however there is no clear consensus on which procedure to perform and when to perform it in these patients. In this original study we describe and explain the rational of our peri-operative approach and management at MD Anderson Cancer Center of MEN1 patients with hyperparathyroidism. This protocol includes preoperative evaluation, intraoperative decision-making and detailed surgical technique adopted for these patients' care. Additionally we review follow-up and disease management in instances of recurrent primary hyperparathyroidism in patients with MEN1 syndrome.

Multiple endocrine neoplasia type 1 with anterior mediastinal parathyroid adenoma: successful localization using Tc-99m sestamibi SPECT/CT

The most common manifestation of multiple endocrine neoplasia type 1 (MEN1) is hyperparathyroidism. Treatment of hyperparathyroidism in MEN patients is surgical removal of the parathyroid glands, however ectopic parathyroid gland is challenging for treatment. A 51-year-old female, the eldest of 3 MEN1 sisters, had hyperparathyroidism with ectopic parathyroid adenoma in the mediastinal para-aortic region, which was detected by technetium-99m (Tc-99m) sestamibi scintigraphy and single-photon emission computed tomography/computed tomography (SPECT/CT). She underwent total parathyroidectomy with video-assisted thoracoscopic surgery on an anterior mediastinal mass. Anterior mediastinal parathyroid adenoma in MEN1 patients is rare. Precise localization of an ectopic parathyroid gland with Tc-99m sestamibi SPECT/CT can lead to successful treatment of hyperparathyroidism. This is the first reported case in the literature of mediastinal parathyroid adenoma in MEN1 patient visualized by Tc-99m sestamibi SPECT/CT.

Clinical and Genetic Analysis of Multiple Endocrine Neoplasia Type 1-Related Primary Hyperparathyroidism in Chinese

Objective

Multiple endocrine neoplasia type 1-related primary hyperparathyroidism (MHPT) differs in many aspects from sporadic PHPT (SHPT). The aims of this study were to summarize the clinical features and genetic background of Chinese MHPT patients and compare the severity of the disease with those of SHPT.

Design and Methods

A total of 40 MHPT (27 sporadic, 7 families) and 169 SHPT cases of Chinese descent were retrospectively analyzed. X-rays and ultrasound were used to assess the bone and urinary system. Dual energy x-ray absorptiometry (DXA) were performed to measure bone mineral density (BMD). Besides direct sequencing of the MEN1 and CDKN1B genes, multiplex ligation-dependent probe amplification (MLPA) was used to screen gross deletion for the MEN1 gene.

Results

Compared with SHPT patients, MHPT patients showed lower prevalence of typical X-ray changes related to PHPT (26.3% vs. 55.7%, P = 0.001) but higher prevalence of urolithiasis/renal calcification (40.2% vs. 60.0%, P = 0.024). MHPT patients showed higher phosphate level (0.84 vs. 0.73mmol/L, P<0.05) but lower ALP (103.0 vs. 174.0U/L, P<0.001) and PTH (4.0 vs. 9.8×upper limit, P<0.001) levels than SHPT patients. There were no significant differences in BMD Z-scores at the lumbar spine and femoral neck between the two groups. Mutations in the MEN1 gene were detected in 27 MHPT cases. Among the nine novel mutations were novel, one of them involved the deletion of exon 5 and 6.

Conclusions

MHPT patients experienced more common kidney complications but less skeletal issues, and a milder biochemical manifestation compared with SHPT patients. MEN1 mutation detection rate was 79.4% and 9 of the identified mutations were novel.

Operative intervention for primary hyperparathyroidism offers greater bone recovery in patients with sporadic disease than in those with multiple endocrine neoplasia type 1-related hyperparathyroidism

BACKGROUND

We investigated whether the outcome of bone disease of primary hyperparathyroidism differs in multiple endocrine neoplasia type 1-associated disease and sporadic hyperparathyroidism at 1-year postoperatively.

METHODS

Multiple endocrine neoplasia type 1/hyperparathyroidism and sporadic hyperparathyroidism patients who underwent parathyroidectomy from 1990 to 2013 and dual-energy x-ray absorptiometry at baseline and 1-year postoperatively were included. Preoperative and postoperative dual-energy x-ray absorptiometry measurements (bone mineral density and Z-score at the lumbar spine, total hip, and femoral neck) were analyzed.

RESULTS

We evaluated 14 multiple endocrine neoplasia type 1/hyperparathyroidism and 104 sporadic hyperparathyroidism patients. The preoperative Z-scores at the lumbar spine, total hip, and femoral neck were lower in the multiple endocrine neoplasia type 1/hyperparathyroidism group (P = .05, P = .04, and P = .0081, respectively). Comparison of preoperative and postoperative dual-energy x-ray absorptiometry measurements demonstrated that the multiple endocrine neoplasia type 1/hyperparathyroidism group had a significantly higher Z-score at the lumbar spine (P = .02) at 1 year after operation, whereas the sporadic hyperparathyroidism group had a significantly higher Z-score at the lumbar spine, total hip, and femoral neck (P < .0001, P = .0004, and P = .0001) and higher bone mineral density at the lumbar spine (P = .0001).

CONCLUSION

Long-term monitoring of these patients using dual-energy x-ray absorptiometry is required to assess outcomes and facilitate decisions on the timing of operative intervention.

Limited Parathyroidectomy in Multiple Endocrine Neoplasia Type 1-Associated Primary Hyperparathyroidism: A Setup for Failure

BACKGROUND

Recently, some surgeons have suggested that minimally invasive parathyroidectomy guided by preoperative localizing studies of patients with multiple endocrine neoplasia type 1 (MEN1)-associated primary hyperparathyroidism (pHPT) provides an acceptable outcome while minimizing the risk of hypoparathyroidism. This study aimed to evaluate the outcome for MEN1 patients who underwent limited parathyroidectomy compared with subtotal parathyroidectomy.

METHODS

The authors performed a retrospective analysis of 99 patients with MEN1-associated pHPT who underwent at least one parathyroid operation at their institution. Preoperative imaging studies, intraoperative findings, and clinical outcomes for patients were compared.

RESULTS

A total of 99 patients underwent 146 operations. Persistent pHPT was significantly higher in patients whose initial operations involved removal of 1 or 2 glands (69 %) or 2.5 to 3 glands (20 %) compared with those who had 3.5 or more glands removed (6 %) (P < 0.01). Persistent pHPT occurred in 5 % of all operations that cumulatively removed 3.5 or more parathyroid glands compared with 40 % of operations that removed 3 or fewer glands (P < 0.01). The single largest parathyroid gland was correctly identified preoperatively in 69 % (22/32) of the patients. However, preoperative localizing studies missed enlarged contralateral parathyroid glands in 86 % (19/22) of these patients. Preoperative localizing studies missed the largest contralateral parathyroid gland in 16 % (5/32) of the patients.

CONCLUSIONS

Limited parathyroidectomy in MEN1 is associated with a high failure rate and should not be performed. Preoperative identification of a single enlarged parathyroid gland in MEN1 is not reliable enough to justify unilateral neck exploration because additional enlarged contralateral parathyroid glands are frequently missed.

Multiple Endocrine Neoplasia: Genetics and Clinical Management

Early diagnosis of multiple endocrine neoplasia (MEN) syndromes is critical for optimal clinical outcomes; before the MEN syndromes can be diagnosed, they must be suspected. Genetic testing for germline alterations in both the MEN type 1 (MEN1) gene and RET proto-oncogene is crucial to identifying those at risk in affected kindreds and directing timely surveillance and surgical therapy to those at greatest risk of potentially life-threatening neoplasia. Pancreatic, thymic, and bronchial neuroendocrine tumors are the leading cause of death in patients with MEN1 and should be aggressively considered by at least biannual computed tomography imaging.

Aortopulmonary window parathyroid gland causing primary hyperparathyroidism in men type 1 syndrome

Primary hyperparathyroidism (HPT) is the most common endocrinopathy in Multiple Endocrine Neoplasia type 1 (MEN1) syndrome. Supernumerary and/or ectopic parathyroid glands, potentially causes of persistent or recurrent HPT after surgery, have been previously described. However, this is the first ever described case of ectopic parathyroid gland localized in the aortopulmunary window causing HPT in MEN1. After a consistent concordant pre-operative imaging assessment the patient, a 16 years old male affected by a severe hypercalcemia, underwent surgery. The parathyroid was found very deeply near the tracheal bifurcation, hidden by the aortic arch itself and for this reason not visible at the beginning of the dissection but only after being identified by palpation for its typical consistence. The intraoperative PTH decreased at normal level 10 min after removal of the ectopic gland. The patient remained with normal value of calcemia and PTH during the 10 months of follow-up.

A differential diagnosis of inherited endocrine tumors and their tumor counterparts

Inherited endocrine tumors have been increasingly recognized in clinical practice, although some difficulties still exist in differentiating these conditions from their sporadic endocrine tumor counterparts. Here, we list the 12 main topics that could add helpful information and clues for performing an early differential diagnosis to distinguish between these conditions. The early diagnosis of patients with inherited endocrine tumors may be performed either clinically or by mutation analysis in at-risk individuals. Early detection usually has a large impact in tumor management, allowing preventive clinical or surgical therapy in most cases. Advice for the clinical and surgical management of inherited endocrine tumors is also discussed. In addition, recent clinical and genetic advances for 17 different forms of inherited endocrine tumors are briefly reviewed.

Molecular diagnosis of primary hyperparathyroidism in familial cancer syndromes

In the last few years, causative genes have been identified for most of the familial hyperparathyroidism conditions. Germline mutations in the tumour suppressors multiple endocrine neoplasia type 1 (MEN1) and hyperparathyroidism 2 (HRPT2) provide a molecular diagnosis of multiple endocrine neoplasia type 1 and hyperparathyroidism jaw tumour syndrome, respectively. Germline mutations in the proto-oncogene RET (rearranged during transfection) provide a molecular diagnosis of multiple endocrine neoplasia type 2. Germline mutations of both MEN1 and, less frequently HRPT2, have been found in familial isolated hyperparathyroidism. A molecular diagnosis can now be incorporated into the management of patients with these conditions, however, the ease of diagnostics and value of genetic information in the context of clinical screening and early surgical intervention varies between these disorders. This review focuses on familial hyperparathyroidism and its known causative genes in the setting of neoplastic syndromes, with particular discussion of recent developments in the molecular diagnosis of parathyroid carcinoma.

Peripheral bone mineral density in correlation to disease-related predisposing conditions in patients with multiple endocrine neoplasia type 1

BACKGROUND AND AIM

Patients with multiple endocrine neoplasia type 1 (MEN1) often have low bone mineral density (BMD) attributed to primary hyperparathyroidism (pHPT). However, in MEN1 patients, other endocrine dysfunctions and conditions such as hypercortisolism, hypogonadism, and GH deficiency due to pituitary manifestation, and surgery on the upper gastrointestinal tract may affect BMD.

SUBJECTS AND METHODS

In 23 patients with MEN1 (10 females, 13 males; 46±12 yr), BMD was determined by quantitative computed tomography at the forearm (pqCT), compared to a reference population and related to different conditions suspected to affect bone metabolism in MEN1.

RESULTS

In this cohort, Z-score for trabecular BMD was -0.85±1.18 and for total BMD -1.16±1.04. There was a similar trend towards lower BMD in uncontrolled hyperparathyroidism, hypercortisolism, hypogonadism/GH deficiency and the state after surgery at the upper gastrointestinal tract.

CONCLUSIONS

These data while confirming previous observations on reduced BMD in patients with MEN1, however, challenge its only or even predominant association with pHPT. Other conditions such as hypercortisolism, somatotrophic/ gonadotrophic pituitary insufficiency, and previous upper gastrointestinal surgery seem to be factors contributing to the risk of developing osteoporosis.

Clinical features of insulinoma in patients with multiple endocrine neoplasia type 1: analysis of the database of the MEN Consortium of Japan

More than 50% of patients with multiple endocrine neoplasia type 1 (MEN1) develop gastroenteropancreatic neuroendocrine tumors (GEPNETs), and insulinoma is the second most common functioning GEPNET. Compared to other functioning and nonfunctioning GEPNETs in MEN1, insulinoma is considered to develop at a younger age. To clarify the clinical features of insulinoma developed in Japanese patients with MEN1, a recently constructed database of Japanese MEN1 patients was analyzed. Among 560 registered cases, insulinoma was seen in 69 patients and information on age at diagnosis was available for 54 patients. Tumors predominantly occurred in the body and tail of the pancreas. The mean age at diagnosis of insulinoma (34.8 ± 16.7 yrs) was significantly younger than that of gastrinoma (50.6 ± 14.3 yrs) and nonfunctioning tumor (44.7 ± 13.3 yrs) in patients with MEN1. Patients diagnosed as having insulinoma during middle-age (30 - 49 yrs) tended to have a long period from appearance of hypoglycemic symptoms to diagnosis of the tumor. Of note, 13 patients (24%) were diagnosed as having insulinoma before 20 yrs of age. Such young onset was not seen in other GEPNETs. Since the development of GEPNETs during adolescence is quite rare, insulinoma diagnosed before 20 yrs strongly suggests the presence of MEN1 and warrants further investigation, including MEN1 genetic testing. Also, clinicians should be aware that insulinoma can often be missed in middle-aged patients.

Post-surgical follow-up of primary hyperparathyroidism associated with multiple endocrine neoplasia type 1

The bone mineral density increments in patients with sporadic primary hyperparathyroidism after parathyroidectomy have been studied by several investigators, but few have investigated this topic in primary hyperparathyroidism associated with multiple endocrine neoplasia type 1. Further, as far as we know, only two studies have consistently evaluated bone mineral density values after parathyroidectomy in cases of primary hyperparathyroidism associated with multiple endocrine neoplasia type 1. Here we revised the impact of parathyroidectomy (particularly total parathyroidectomy followed by autologous parathyroid implant into the forearm) on bone mineral density values in patients with primary hyperparathyroidism associated with multiple endocrine neoplasia type 1. Significant increases in bone mineral density in the lumbar spine and femoral neck values were found, although no short-term (15 months) improvement in bone mineral density at the proximal third of the distal radius was observed. Additionally, short-term and medium-term calcium and parathyroid hormone values after parathyroidectomy in patients with primary hyperparathyroidism associated with multiple endocrine neoplasia type 1 are discussed. In most cases, this surgical approach was able to restore normal calcium/parathyroid hormone levels and ultimately lead to discontinuation of calcium and calcitriol supplementation.

Biochemical, bone and renal patterns in hyperparathyroidism associated with multiple endocrine neoplasia type 1

Primary hyperparathyroidism associated with multiple endocrine neoplasia type I (hyperparathyroidism/multiple endocrine neoplasia type 1) differs in many aspects from sporadic hyperparathyroidism, which is the most frequently occurring form of hyperparathyroidism. Bone mineral density has frequently been studied in sporadic hyperparathyroidism but it has very rarely been examined in cases of hyperparathyroidism/multiple endocrine neoplasia type 1. Cortical bone mineral density in hyperparathyroidism/multiple endocrine neoplasia type 1 cases has only recently been examined, and early, severe and frequent bone mineral losses have been documented at this site. Early bone mineral losses are highly prevalent in the trabecular bone of patients with hyperparathyroidism/multiple endocrine neoplasia type 1. In summary, bone mineral disease in multiple endocrine neoplasia type 1 related hyperparathyroidism is an early, frequent and severe disturbance, occurring in both the cortical and trabecular bones. In addition, renal complications secondary to sporadic hyperparathyroidism are often studied, but very little work has been done on this issue in hyperparathyroidism/multiple endocrine neoplasia type 1. It has been recently verified that early, frequent, and severe renal lesions occur in patients with hyperparathyroidism/multiple endocrine neoplasia type 1, which may lead to increased morbidity and mortality. In this article we review the few available studies on bone mineral and renal disturbances in the setting of hyperparathyroidism/multiple endocrine neoplasia type 1. We performed a meta-analysis of the available data on bone mineral and renal disease in cases of multiple endocrine neoplasia type 1-related hyperparathyroidism.

Surgical approach in patients with hyperparathyroidism in multiple endocrine neoplasia type 1: total versus partial parathyroidectomy

Usually, primary hyperparathyroidism is the first endocrinopathy to be diagnosed in patients with multiple endocrine neoplasia type 1, and is also the most common one. The timing of the surgery and strategy in multiple endocrine neoplasia type 1/hyperparathyroidism are still under debate. The aims of surgery are to: 1) correct hypercalcemia, thus preventing persistent or recurrent hyperparathyroidism; 2) avoid persistent hypoparathyroidism; and 3) facilitate the surgical treatment of possible recurrences. Currently, two types of surgical approach are indicated: 1) subtotal parathyroidectomy with removal of at least 3-3 K glands; and 2) total parathyroidectomy with grafting of autologous parathyroid tissue. Transcervical thymectomy must be performed with both of these procedures. Unsuccessful surgical treatment of hyperparathyroidism is more frequently observed in multiple endocrine neoplasia type 1 than in sporadic hyperparathyroidism. The recurrence rate is strongly influenced by: 1) the lack of a pre-operative multiple endocrine neoplasia type 1 diagnosis; 2) the surgeon's experience; 3) the timing of surgery; 4) the possibility of performing intra-operative confirmation (histologic examination, rapid parathyroid hormone assay) of the curative potential of the surgical procedure; and, 5) the surgical strategy. Persistent hyperparathyroidism seems to be more frequent after subtotal parathyroidectomy than after total parathyroidectomy with autologous graft of parathyroid tissue. Conversely, recurrent hyperparathyroidism has a similar frequency in the two surgical strategies. To plan further operations, it is very helpful to know all the available data about previous surgery and to undertake accurate identification of the site of recurrence.

Surgical management of pancreatico-duodenal tumors in multiple endocrine neoplasia syndrome type 1

Pancreatico-duodenal tumors are the second most common endocrinopathy in multiple endocrine neoplasia syndrome type 1, and have a pronounced effect on life expectancy as the principal cause of disease-related death. Previous discussions about surgical management have focused mainly on syndromes of hormone excess and, in particular, the management of multiple endocrine neoplasia syndrome type 1-related Zollinger-Ellison syndrome. Since hormonal syndromes tend to occur late and indicate the presence of metastases, screening with biochemical markers and endoscopic ultrasound is recommended for early detection of pancreatico-duodenal tumors, and with early surgery before metastases have developed. Surgery is recommended in patients with or without hormonal syndromes in the absence of disseminated liver metastases. The suggested operation includes distal 80% subtotal pancreatic resection together with enucleation of tumors in the head of the pancreas, and in cases with Zollinger-Ellison syndrome, excision of duodenal gastrinomas together with clearance of regional lymph node metastases. This strategy, with early and aggressive surgery before metastases have developed, is believed to reduce the risks for tumor recurrence and malignant progression.

Primary hyperparathyroidism in multiple endocrine neoplasia type 1: when to perform surgery?

Primary hyperparathyroidism is a common endocrinological disorder. In rare circumstances, it is associated with familial syndromes, such as multiple endocrine neoplasia type 1. This syndrome is caused by a germline mutation in the multiple endocrine neoplasia type 1 gene encoding the tumor-suppressor protein menin. Usually, primary hyperparathyroidism is the initial clinical expression in carriers of multiple endocrine neoplasia type 1 mutations, occurring in more than 90% of patients and appearing at a young age (20-25 years). Multiple endocrine neoplasia type 1/primary hyperparathyroidism is generally accompanied by multiglandular disease, clinically manifesting with hypercalcemia, although it can remain asymptomatic for a long time and consequently not always be recognized early. Surgery is the recommended treatment. The goal of this short review is to discuss the timing of surgery in patients when primary hyperparathyroidism is associated with multiple endocrine neoplasia type 1.