Pituitary Tumors and Hyperplasia in Multiple Endocrine Neoplasia Type 1 Syndrome (MEN1): A Case-Control Study in a Series of 77 Patients Versus 2509 Non-MEN1 Patients

Long term outcomes of pituitary adenomas in Multiple Endocrine Neoplasia type 1: a nationwide study

Introduction

Historically, Multiple Endocrine Neoplasia type 1 (MEN1)-related pituitary adenomas (PAs) were considered more aggressive and treatment-resistant than sporadic PAs. However, recent studies suggest similarities in their behavior. This study aimed to evaluate the long-term outcomes of MEN1 PAs and identify predictive factors.

Methods

Nationwide multicenter retrospective cohort study of MEN1-related PAs with a minimum 1-year follow-up, collecting patient demographics, germline MEN1 pathogenic variants (PV), PA size, secretory profile, radiological characteristics, treatments, and outcomes.

Results

We analyzed 84 PAs, 69%in females and 31% in males (P<0.001), diagnosed at a mean age of 35.2±14.9 years, mostly through screening (60.7%). Median follow-up was 9 years (IQR:4-16). Prolactin-secreting PAs (PRLomas) (53.5%) and microadenomas (65.5%) were most common. Dopamine agonist treatment was first line for 16 macroPRLomas and 25 microPRLomas, 60.9% of them achieved PRL normalization. There was no significant association observed with tumor size, sex, treatment duration or MEN1 PV. The risk of progression from micro-PA to invasive macro-PA was 7.2% (4/55), after 8 years (IQR:4-13), all of them were microPRLomas. Kaplan-Meier estimation curve showed significantly higher progression probability in microPRLomas than in other microadenomas subtypes (P=0.017) or microNFPAs (P=0.032). No differences were found between sex, age, or germline MEN1 PV.

Conclusion

MEN1-related micro-PAs have a low risk of progressing to invasive macro-PAs, regardless of sex, age at diagnosis, or MEN1 germline PV. The risk is higher for microPRLomas over the long term. Therefore, long-term surveillance with reduced frequency, rather than intensive short-term monitoring, may be appropriate for patients with MEN1-related PAs.

An Update on the Genetic Drivers of Corticotroph Tumorigenesis

The genetic landscape of corticotroph tumours of the pituitary gland has dramatically changed over the last 10 years. Somatic changes in the USP8 gene account for the most common genetic defect in corticotrophinomas, especially in females, while variants in TP53 or ATRX are associated with a subset of aggressive tumours. Germline defects have also been identified in patients with Cushing's disease: some are well-established (MEN1, CDKN1B, DICER1), while others are rare and could represent coincidences. In this review, we summarise the current knowledge on the genetic drivers of corticotroph tumorigenesis, their molecular consequences, and their impact on the clinical presentation and prognosis.

Histopathology of growth hormone-secreting pituitary tumors: State of the art and new perspectives

Somatotroph (GH) adenomas/PitNETs typically arise from adenohypophysis and are biochemically active, leading to acromegaly and gigantism. More rarely, they present with ectopic origin and do not present overt biochemical or clinical features (silent variants). Histopathological examination should consider the clinical and radiological background, and include multiple steps assessing tumor morphology, pituitary transcription factors (PTFs), hormone secretion, proliferation markers, granulation, and somatostatin receptors (STRs), aimed at depicting as better as possible tumor origin (in case of non-functioning and/or metastatic tumor), and clinical behavior, including response to treatment. GH-secreting tumors are part of the Pit-1 family tumors and can secrete GH only (pure somatotrophs) or co-secrete prolactin (mixed tumors; in this case, various histological subtypes have been identified). Each subtype presents unique radiological, biochemical, and clinical characteristic. Therefore, the integration of biochemical, clinical, radiological, and histopathological elements is fundamental for proper diagnosis and management of pituitary adenomas/PitNETs, to be performed in referral Centers. In more recent times, the importance of genetic and epigenetic evaluation in the characterization of pituitary tumors (i.e., early identification of aggressive variants) has been outlined by some large studies, with the intention of improving targeted treatments.

Genetic diagnosis in acromegaly and gigantism: From research to clinical practice

It is usually considered that only 5% of all pituitary neuroendocrine tumours are due to inheritable causes. Since this estimate was reported, however, multiple genetic defects driving syndromic and nonsyndromic somatotrophinomas have been unveiled. This heterogeneous genetic background results in overlapping phenotypes of GH excess. Genetic tests should be part of the approach to patients with acromegaly and gigantism because they can refine the clinical diagnoses, opening the possibility to tailor the clinical conduct to each patient. Even more, genetic testing and clinical screening of at-risk individuals have a positive impact on disease outcomes, by allowing for the timely detection and treatment of somatotrophinomas at early stages. Future research should focus on determining the actual frequency of novel genetic drivers of somatotrophinomas in the general population, developing up-to-date disease-specific multi-gene panels for clinical use, and finding strategies to improve access to modern genetic testing worldwide.

Pancreatic GHRHomas in Patients with or without Multiple Endocrine Neoplasia Type 1 (MEN 1) : An Analysis of 36 Reported Cases

Pancreatic GHRHomas (pGHRHomas) with acromegaly have unique conditions, harboring the existence of multiple endocrine neoplasia type 1 (MEN 1). Moreover, pituitary lesions are affected by both protracted ectopic GHRH and loss of menin function. Of significance is the clarification of clinicopathological aspects of pGHRHomas in patients with or without MEN 1. From 1977-2016, thirty-six patients with pGHRHomas were reported. Twenty-two out of 36 patients (61%) had pGHRHomas with MEN 1 and 14 patients did not. The former had a tendency of male predominance, benign tumor behavior and fewer metastasis rather than the latter. The latter is a single pGHRHoma accompanied by pituitary enlargement with somatotroph hyperplasia (hyperplasia) caused by protracted ectopic GHRH. Nine patients with MEN 1 underwent transsphenoidal surgery (TSS). The hyperplasia associated with various pituitary adenomas (PAs) including three GH-related adenomas was observed in seven subjects (32%). In these patients, the resection of their pGHRHomas was feasible. Furthermore, all patients with acromegaly due to pGHRHomas without MEN 1 had non-TSS, whereas approximately 70% of those with MEN 1 had unnecessary TSS. The association with hyperplasia and various PAs suggested that formation of the three GH-related adenomas may be induced by the foundations of MEN 1 gene mutations. J. Med. Invest. 71 : 1-8, February, 2024.

Genetic Testing in Hereditary Pituitary Tumors

Genetic testing is becoming part of mainstream endocrinology. An increasing number of rare and not-so-rare endocrine diseases have an identifiable genetic cause, either at the germline or at the somatic level. Here we summerise germline genetic alterations in patients with pituitary neuroendocrine tumors (pituitary adenomas). These may be disorders with isolated pituitary tumors, such as X-linked acrogigantism, or AIP-related pituitary tumors, or as part of syndromic diseases, such as multiple endocrine neoplasia type 1 or Carney complex. In some cases, this could be relevant for treatment choices and follow-up, as well as for family members, as cascade screening leads to early identification of affected relatives and improved clinical outcomes.

Traits of Patients With Pituitary Tumors in Multiple Endocrine Neoplasia Type 1 and Comparing Different Mutation Status

CONTEXT

Recent studies suggest that the clinical characteristics and biological behavior of pituitary tumors (PITs) in patients with multiple endocrine neoplasia type 1 (MEN1) may not be as aggressive as previously reported. Increased imaging of the pituitary as recommended by screening guidelines identifies more tumors, potentially at an earlier stage. However, it is unknown if these tumors have different clinical characteristics in different MEN1 mutations.

OBJECTIVE

To assess characteristics of patients with MEN1 with and without PITs, and compare among different MEN1 mutations.

METHODS

Data of patients with MEN1 in a tertiary referral center from 2010 to 2023 were retrospectively analyzed.

RESULTS

Forty-two patients with MEN1 were included. Twenty-four patients had PITs, 3 of which were invasive and managed with transsphenoidal surgery. One PIT enlarged during follow-up. Patients with PITs had a higher median age at MEN1 diagnosis than those without PITs. MEN1 mutations were identified in 57.1% of patients, including 5 novel mutations. In patients with PITs, those with MEN1 mutations (mutation+/PIT+ group) had more additional MEN1-associated tumors than those without (mutation-/PIT+ group). The mutation+/PIT+ group had a higher incidence of adrenal tumors and a lower median age at initial manifestation of MEN1 than the mutation-/PIT+ group. The most common neuroendocrine neoplasm was nonfunctional in the mutation+/PIT+ group and insulin-secreting in the mutation-/PIT+ group.

CONCLUSION

This is the first study comparing characteristics of patients with MEN1 with and without PITs harboring different mutations. Patients without MEN1 mutations tended to have less organ involvement and it might be reasonable for them to receive less intensive follow-up.

Molecular and Clinical Spectrum of Primary Hyperparathyroidism

Recent data suggest an increase in the overall incidence of parathyroid disorders, with primary hyperparathyroidism (PHPT) being the most prevalent parathyroid disorder. PHPT is associated with morbidities (fractures, kidney stones, chronic kidney disease) and increased risk of death. The symptoms of PHPT can be nonspecific, potentially delaying the diagnosis. Approximately 15% of patients with PHPT have an underlying heritable form of PHPT that may be associated with extraparathyroidal manifestations, requiring active surveillance for these manifestations as seen in multiple endocrine neoplasia type 1 and 2A. Genetic testing for heritable forms should be offered to patients with multiglandular disease, recurrent PHPT, young onset PHPT (age ≤40 years), and those with a family history of parathyroid tumors. However, the underlying genetic cause for the majority of patients with heritable forms of PHPT remains unknown. Distinction between sporadic and heritable forms of PHPT is useful in surgical planning for parathyroidectomy and has implications for the family. The genes currently known to be associated with heritable forms of PHPT account for approximately half of sporadic parathyroid tumors. But the genetic cause in approximately half of the sporadic parathyroid tumors remains unknown. Furthermore, there is no systemic therapy for parathyroid carcinoma, a rare but potentially fatal cause of PHPT. Improved understanding of the molecular characteristics of parathyroid tumors will allow us to identify biomarkers for diagnosis and novel targets for therapy.

An update on, and genetics of refractory adenomas of childhood

Pituitary adenomas in childhood tend to be more frequently due to germline genetic changes and are often diagnosed at late stages due to delayed recognition by pediatricians and other caretakers who are not familiar with this rare disease in childhood. As a result, often, pediatric pituitary adenomas are aggressive or remain refractory to treatment. In this review, we discuss germline genetic defects that account for the most common pediatric pituitary adenomas that are refractory to treatment. We also discuss some somatic genetic events, such as chromosomal copy number changes that characterize some of the most aggressive pituitary adenomas in childhood that end up being refractory to treatment.

The Effects of Peptide Receptor Radionuclide Therapy on the Neoplastic and Normal Pituitary

Pituitary neuroendocrine tumours (PitNETs) are usually benign and slow-growing; however, in some cases, they may behave aggressively and become resistant to conventional treatments. Therapeutic options for aggressive or metastatic PitNETs are limited, and currently mainly consist of temozolomide, with little experience of other emerging approaches, including peptide receptor radionuclide therapy (PRRT). Somatostatin receptor expression in PitNETs explains the effectiveness of somatostatin analogues for treating PitNETs, particularly those hypersecreting pituitary hormones, such as growth hormone or adrenocorticotropic hormone. The expression of such receptors in pituitary tumour cells has provided the rationale for using PRRT to treat patients with aggressive or metastatic PitNETs. However, the PRRT efficacy in this setting remains unestablished, as knowledge on this today is based only on few case reports and small series of cases, which are reviewed here. A total of 30 PRRT-treated patients have been thus far reported: 23 aggressive PitNETs, 5 carcinomas, and 2 of malignancy status unspecified. Of the 27 published cases with information regarding the response to PRRT, 5 (18%) showed a partial response, 8 (30%) had stable disease, and 14 (52%) had progressive disease. No major adverse effects have been reported, and there is also no increased risk of clinically relevant hypopituitarism in patients with pituitary or non-pituitary neuroendocrine tumours following PRRT. PRRT may be regarded as a safe option for patients with aggressive or metastatic PitNETs if other treatment approaches are not feasible or have failed in controlling the disease progression, with tumour shrinkage occurring in up to a fifth of cases, while about a third of aggressive pituitary tumours may achieve stable disease. Here, the data on PRRT in the management of patients with aggressive pituitary tumours are reviewed, as well as the effects of PRRT on the pituitary function in other PRRT-treated cancer patients.

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.

The Spectrum of Familial Pituitary Neuroendocrine Tumors

Hereditary pituitary tumorigenesis is seen in a relatively small proportion (around 5%) of patients with pituitary neuroendocrine tumors (PitNETs). The aim of the current review is to describe the main clinical and molecular features of such pituitary tumors associated with hereditary or familial characteristics, many of which have now been genetically identified. The genetic patterns of inheritance are classified into isolated familial PitNETs and the syndromic tumors. In general, the established genetic causes of familial tumorigenesis tend to present at a younger age, often pursue a more aggressive course, and are more frequently associated with growth hormone hypersecretion compared to sporadic tumors. The mostly studied molecular pathways implicated are the protein kinase A and phosphatidyl-inositol pathways, which are in the main related to mutations in the syndromes of familial isolated pituitary adenoma (FIPA), Carney complex syndrome, and X-linked acrogigantism. Another well-documented mechanism consists of the regulation of p27 or p21 proteins, with further acceleration of the pituitary cell cycle through the check points G1/S and M/G1, mostly documented in multiple endocrine neoplasia type 4. In conclusion, PitNETs may occur in relation to well-established familial germline mutations which may determine the clinical phenotype and the response to treatment, and may require family screening.

The Classic, the Trendy, and the Refashioned: A Primer for Pathologists on What Is New in Familial Endocrine Tumor Syndromes

Familial endocrine tumor syndromes are continuously expanding owing to the growing role of genetic testing in routine clinical practice. Pathologists are usually the first on the clinical team to encounter these syndromes at their initial presentation; thus, recognizing them is becoming more pivotal in routine pathology practice to help in properly planning management and further family testing. Our increasing knowledge about them is reflected in the newer syndromes included in the new World Health Organization classification and in the evolving discovery of new endocrine tumors and new familial associations. In many of these syndromes, the clinical features and co-occurrence of multiple neoplasia are the only clues (multiple endocrine neoplasia syndromes). In other syndromes, specific morphologic findings (pituitary blastoma and DICER1 syndrome, cribriform morular thyroid carcinoma, and AFP syndrome) and available ancillary studies (SDHB in SDH-deficient tumor syndromes) can aid pathologists. The aim of this review is to provide a primer on recent updates on familial endocrine tumor syndromes and related tumors, focusing on recent classification changes or tumor syndromes where a clearer role for pathologists is at play.

Preoperative Risk Stratification of Increased MIB-1 Labeling Index in Pituitary Adenoma: A Newly Proposed Prognostic Scoring System

The MIB-1 index is an important risk factor for progression-free survival (PFS) in pituitary adenoma (PA). Preoperatively, the MIB-1 index is not available in the decision-making process. A preoperative method regarding MIB-1 index estimation in PA has not been evaluated so far. Between 2011 and 2021, 109 patients with tumor morphology data, MIB-1 index data, and inflammatory and pituitary hormone laboratory values underwent surgery for PA. An MIB-1 index cutoff point (≥4/<4%) determines the probability of PFS in completely resected PA. An elevated MIB-1 index (≥4%) was present in 32 cases (29.4%) and was significantly associated with increased IGF-1, age ≤ 60, increased ACTH, and increased fibrinogen levels in the multivariable analysis. A scoring system (“FATE”) using preoperative IGF-1, age, ACTH, and plasma fibrinogen level enables the estimation of the MIB-1 index (sensitivity 72%, specificity 68%). The FATE score is also significantly associated with the time to PA progression after the complete resection of the PA. We propose the FATE score to preoperatively estimate the risk of an elevated MIB-1 index (≥4%), which might enable tailoring to medical decision-making, and follow-up interval scheduling, as well as inform future studies analyzing proliferative activities.

Clinical Biology of the Pituitary Adenoma

All endocrine glands are susceptible to neoplastic growth, yet the health consequences of these neoplasms differ between endocrine tissues. Pituitary neoplasms are highly prevalent and overwhelmingly benign, exhibiting a spectrum of diverse behaviors and impact on health. To understand the clinical biology of these common yet often innocuous neoplasms, we review pituitary physiology and adenoma epidemiology, pathophysiology, behavior, and clinical consequences. The anterior pituitary develops in response to a range of complex brain signals integrating with intrinsic ectodermal cell transcriptional events that together determine gland growth, cell type differentiation, and hormonal production, in turn maintaining optimal endocrine health. Pituitary adenomas occur in 10% of the population; however, the overwhelming majority remain harmless during life. Triggered by somatic or germline mutations, disease-causing adenomas manifest pathogenic mechanisms that disrupt intrapituitary signaling to promote benign cell proliferation associated with chromosomal instability. Cellular senescence acts as a mechanistic buffer protecting against malignant transformation, an extremely rare event. It is estimated that fewer than one-thousandth of all pituitary adenomas cause clinically significant disease. Adenomas variably and adversely affect morbidity and mortality depending on cell type, hormone secretory activity, and growth behavior. For most clinically apparent adenomas, multimodal therapy controlling hormone secretion and adenoma growth lead to improved quality of life and normalized mortality. The clinical biology of pituitary adenomas, and particularly their benign nature, stands in marked contrast to other tumors of the endocrine system, such as thyroid and neuroendocrine tumors.

Molecular genetic testing in the management of pituitary disease

OBJECTIVE

Most pituitary tumours occur sporadically without a genetically identifiable germline abnormality, a small but increasing proportion present with a genetic defect that predisposes to pituitary tumour development, either isolated (e.g., aryl hydrocarbon receptor-interacting protein, AIP) or as part of a tumour-predisposing syndrome (e.g., multiple endocrine neoplasia (MEN) type 1, Carney complex, McCune-Albright syndrome or pituitary tumour and paraganglioma association). Genetic alterations in sporadic pituitary adenomas may include somatic mutations (e.g., GNAS, USP8). In this review, we take a practical approach: which genetic syndromes should be considered in case of different presentation, such as tumour type, family history, age of onset and additional clinical features of the patient.

DESIGN

Review of the recent literature in the field of genetics of pituitary tumours.

RESULTS

Genetic testing in the management of pituitary disease is recommended in a significant minority of the cases. Understanding the genetic basis of the disease helps to identify patients and at-risk family members, facilitates early diagnosis and therefore better long-term outcome and opens up new pathways leading to tumorigenesis.

CONCLUSION

We provide a concise overview of the genetics of pituitary tumours and discuss the current challenges and implications of these genetic findings in clinical practice.

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.

Neurofibromatosis Type 1 Has a Wide Spectrum of Growth Hormone Excess

Overgrowth due to growth hormone (GH) excess affects approximately 10% of patients with neurofibromatosis type 1 (NF1) and optic pathway glioma (OPG). Our aim is to describe the clinical, biochemical, pathological, and genetic features of GH excess in a retrospective case series of 10 children and adults with NF1 referred to a tertiary care clinical research center. Six children (median age = 4 years, range of 3−5 years), one 14-year-old adolescent, and three adults (median age = 42 years, range of 29−52 years) were diagnosed with NF1 and GH excess. GH excess was confirmed by the failure to suppress GH (<1 ng/mL) on oral glucose tolerance test (OGTT, n = 9) and frequent overnight sampling of GH levels (n = 6). Genetic testing was ascertained through targeted or whole-exome sequencing (n = 9). Five patients (all children) had an OPG without any pituitary abnormality, three patients (one adolescent and two adults) had a pituitary lesion (two tumors, one suggestive hyperplasia) without an OPG, and two patients (one child and one adult) had a pituitary lesion (a pituitary tumor and suggestive hyperplasia, respectively) with a concomitant OPG. The serial overnight sampling of GH levels in six patients revealed abnormal overnight GH profiling. Two adult patients had a voluminous pituitary gland on pituitary imaging. One pituitary tumor from an adolescent patient who harbored a germline heterozygous p.Gln514Pro NF1 variant stained positive for GH and prolactin. One child who harbored a heterozygous truncating variant in exon 46 of NF1 had an OPG that, when compared to normal optic nerves, stained strongly for GPR101, an orphan G protein-coupled receptor causing GH excess in X-linked acrogigantism. We describe a series of patients with GH excess and NF1. Our findings show the variability in patterns of serial overnight GH secretion, somatotroph tumor or hyperplasia in some cases of NF1 and GH excess. Further studies are required to ascertain the link between NF1, GH excess and GPR101, which may aid in the characterization of the molecular underpinning of GH excess in NF1.

The Importance of Periodical Screening for Primary Hyperparathyroidism in a Pituitary Tumor Cohort in Searching Patients with MEN1 and its Genetic Profile

OBJECTIVE

Multiple endocrine neoplasia type 1 (MEN1) is a rare genetic syndrome characterized by parathyroid, anterior pituitary, and/or duodenopancreatic neuroendocrine tumors. Studies have indicated that investigating primary hyperparathyroidism (pHPT) with subsequent genetic screening may be an essential tool for the early diagnosis of MEN1 in patients with pituitary tumors (PTs). This study aimed to investigate the presence of pHPT in patients with PTs and, subsequently, to screen for genetic mutations and related tumors in those with MEN1 Syndrome.

METHODS

This study included 255 patients with PTs who were assessed for the presence of MEN1 from serum calcium and parathyroid hormone measurements. Mutation screening of the MEN1, CDKN1B, and AIP genes was performed in the index cases showing the MEN1 phenotype.

RESULTS

Five PT-evaluated patients presented a clinical condition compatible with MEN1. These patients had a younger age of onset and a more severe clinical condition. Genetic analysis identified a frameshift mutation in the MEN1 gene in one of the cases with the MEN1 phenotype, but point mutations in CDKN1B and AIP were not detected in any of these patients.

CONCLUSION

Our findings show that periodic screening for pHPT in patients with PTs may be useful to detect MEN1 syndrome; thus, it is recommended in those patients genetic analysis of MEN1 gene and an additional search of related tumors. By contrast, our results suggest that CDKN1B and AIP mutations do not seem to play a relevant role in the pathogenesis of MEN1.

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.

Mixed gangliocytoma-pituitary adenoma in MEN1 syndrome: A case report and literature review

Pituitary adenoma is one of the three most common neoplasms described in multiple endocrine neoplasia type 1 (MEN1), and patients with pituitary adenoma occupies 30-50% of those with MEN1-related tumor. Mixed gangliocytoma-pituitary adenoma (MGPA) is a rare clinical entity in which gangliomatous cells are intermixed with adenomatous cells. This tumor has been estimated to account for 0.52-1.26% of all pituitary tumors. We report a rare case of MGPA in a patient with MEN1. A retrospective chart review was conducted on a patient with MEN1 diagnosed with MGPA in 2019 at a single tertiary academic medical center. A review of the literature was performed on MGPA and pituitary adenoma in MEN1. MGPA is rare, with only 174 cases previously reported in the literature and only three prior case reported in a patient with MEN1. There are multiple hypotheses regarding their pathogenesis, and it is unclear whether the MEN1 gene (menin) plays a role in the pathogenesis of MGPA. This tumor in MEN1 is a rare clinical entity of unknown etiology. Further studies are required with difficulty due to its low incidence.

Quantitative proteomics revealed the molecular characteristics of distinct types of granulated somatotroph adenomas

PURPOSE

Somatotroph adenomas are obviously heterogeneous in clinical characteristics, imaging performance, pathological diagnosis and therapeutic effect. The heterogeneity of the tumors, especially for SG and DG type adenomas, have attracted great interest in identifying the specific pathological markers and therapeutic targets of them. However, previous analyses of the molecular characteristics of the subtypes of somatotroph adenomas were performed at genomic and transcriptome level. The proteomic differences between the two subtypes of somatotroph adenomas are still unknown.

METHODS

Tumor samples were surgically removed from 10 sporadic pituitary somatotroph adenoma patients and grouped according to the pathological type. Tandem mass tag (TMT)-based quantitative proteomic analysis was employed to analyze the proteomic differences between SG and DG tumors.

RESULTS

In total, 228 differentially expressed proteins were identified between SG adenomas and DG adenomas. They were enriched mainly in extracellular matrix (ECM)-receptor interaction, leukocyte transendothelial migration, arrhythmogenic right ventricular cardiomyopathy and DNA replication pathways. Protein-protein interaction (PPI) network analysis indicated that Cadherin-1 and Catenin beta-1 were the most important key proteins in the differences between SG and DG adenomas. Immunohistochemistry (IHC) confirmed the expression levels of the key proteins.

CONCLUSIONS

This study provides large-scale proteome molecular characteristics of distinct granulation subtypes of somatotroph adenomas. Compared with DG adenomas, The differential protein of SG adenomas mostly enrich in invasive and proliferative functions and pathways at the proteomic level. Cadherin-1 and Catenin beta-1 play key roles in the different biological characteristics of the two tumor subtypes.

Aggressive pituitary tumours and pituitary carcinomas

Although usually benign, anterior pituitary tumours occasionally exhibit aggressive behaviour, with invasion of surrounding tissues, rapid growth, resistance to conventional treatments and multiple recurrences. In very rare cases, they metastasize and are termed pituitary carcinomas. The time between a 'classical' pituitary tumour and a pituitary carcinoma can be years, which means that monitoring should be performed regularly in patients with clinical (invasion and/or tumour growth) or pathological (Ki67 index, mitotic count and/or p53 detection) markers suggesting aggressiveness. However, although both invasion and proliferation have prognostic value, such parameters cannot predict outcome or malignancy without metastasis. Future research should focus on the biology of both tumour cells and their microenvironment, hopefully with improved therapeutic outcomes. Currently, the initial therapeutic approach for aggressive pituitary tumours is generally to repeat surgery or radiotherapy in expert centres. Standard medical treatments usually have no effect on tumour progression but they can be maintained on a long-term basis to, at least partly, control hypersecretion. In cases where standard treatments prove ineffective, temozolomide, the sole formally recommended treatment, is effective in only one-third of patients. Personalized use of emerging therapies, including peptide receptor radionuclide therapy, angiogenesis-targeted therapy and immunotherapy, will hopefully improve the outcomes of patients with this severe condition.

Clinically non-functioning pituitary adenomas

Clinically non functioning pituitary adenomas (NFPAs) include all pituitary adenomas that are not hormonally active. They are not associated with clinical syndromes such as amenorrhea-galactorrhea (prolactinomas), acromegaly, Cushing's disease or hyperthyroidism (TSH-secreting adenomas) and are therefore usually diagnosed by signs and symptoms related to a mass effect (headache, visual impairment, sometimes pituitary apoplexy), but also incidentally. Biochemical work up often documents several pituitary insufficiencies. In histopathology, the majority of NFPAs are gonadotroph. In the absence of an established medical therapy, surgery is the mainstay of treatment, unless contraindicated or in particular situations (e.g. small incidentalomas, distance from optic pathways). Resection, generally via a trans-sphenoidal approach (with the help of an endoscope), should be performed by a neurosurgeon with extensive experience in pituitary surgery, in order to maximize the chances of complete resection and to minimize complications. If a tumor remnant persists, watchful waiting is preferred to routine radiotherapy, as long as the tumor residue does not grow and is distant from the optic pathways. NFPA can sometimes recur even after complete resection, but predicting the individual risk of tumor remnant progression is difficult. Postoperative irradiation is only considered in case of residual tumor growth or relapse, due to its potential side effects.

Pituitary neuroendocrine tumors: a model for neuroendocrine tumor classification

The classification of adenohypophysial neoplasms as "pituitary neuroendocrine tumors" (PitNETs) was proposed in 2017 to reflect their characteristics as epithelial neuroendocrine neoplasms with a spectrum of clinical behaviors ranging from small indolent lesions to large, locally invasive, unresectable tumors. Tumor growth and hormone hypersecretion cause significant morbidity and mortality in a subset of patients. The proposal was endorsed by a WHO working group that sought to provide a unified approach to neuroendocrine neoplasia in all body sites. We review the features that are characteristic of neuroendocrine cells, the epidemiology and prognosis of these tumors, as well as further refinements in terms used for other pituitary tumors to ensure consistency with the WHO framework. The intense study of PitNETs has provided information about the importance of cellular differentiation in tumor prognosis as a model for neuroendocrine tumors in different locations.

[The clinical practice guidelines for primary hyperparathyroidism, short version]

Primary hyperparathyroidism (PHPT) is an endocrine disorder of parathyroid glands characterized by excessive secretion of parathyroid hormone (PTH) with an upper normal or elevated blood calcium level. Classical PHPT refers to a symptomatic, multi-system disorder, wich can lead to a significant decrease in the quality of life, disability of patients, and even an increased risk of premature death. Hypercalcemia and the catabolic effect of PTH on various cells are considered as the main pathogenetic mechanisms of the PHPT associated complications. In the last two decades, there has been an increase in the incidence of PHPT, mainly due to the mild forms of the disease, primarily due to the routine calcium screening in North America, Western Europe and, Asia. High prevalence of the disease, as well as the variety of clinical manifestations, cause the attention of different specialists - physicians, rheumatologists, urologists, nephrologists, cardiologists and other doctors. This review cover the main issues of Russian guidelines for the management of PHPT, approved in 2020, including laboratory and instrumental methods, differential diagnosis, surgical and conservative approach, short-term and long-term follow-up. This guidelines also include the recommendations for special groups of patients with hereditary forms of PHPT, parathyroid carcinoma, PHPT during pregnancy.

GHRH secretion from a pancreatic neuroendocrine tumor causing gigantism in a patient with MEN1

SUMMARY

A male patient with a germline mutation in MEN1 presented at the age of 18 with classical features of gigantism. Previously, he had undergone resection of an insulin-secreting pancreatic neuroendocrine tumour (pNET) at the age of 10 years and had subtotal parathyroidectomy due to primary hyperparathyroidism at the age of 15 years. He was found to have significantly elevated serum IGF-1, GH, GHRH and calcitonin levels. Pituitary MRI showed an overall bulky gland with a 3 mm hypoechoic area. Abdominal MRI showed a 27 mm mass in the head of the pancreas and a 6 mm lesion in the tail. Lanreotide-Autogel 120 mg/month reduced GHRH by 45% and IGF-1 by 20%. Following pancreaticoduodenectomy, four NETs were identified with positive GHRH and calcitonin staining and Ki-67 index of 2% in the largest lesion. The pancreas tail lesion was not removed. Post-operatively, GHRH and calcitonin levels were undetectable, IGF-1 levels normalised and GH suppressed normally on glucose challenge. Post-operative fasting glucose and HbA1c levels have remained normal at the last check-up. While adolescent-onset cases of GHRH-secreting pNETs have been described, to the best of our knowledge, this is the first reported case of ectopic GHRH in a paediatric setting leading to gigantism in a patient with MEN1. Our case highlights the importance of distinguishing between pituitary and ectopic causes of gigantism, especially in the setting of MEN1, where paediatric somatotroph adenomas causing gigantism are extremely rare.

LEARNING POINTS

It is important to diagnose gigantism and its underlying cause (pituitary vs ectopic) early in order to prevent further growth and avoid unnecessary pituitary surgery. The most common primary tumour sites in ectopic acromegaly include the lung (53%) and the pancreas (34%) (1): 76% of patients with a pNET secreting GHRH showed a MEN1 mutation (1). Plasma GHRH testing is readily available in international laboratories and can be a useful diagnostic tool in distinguishing between pituitary acromegaly mediated by GH and ectopic acromegaly mediated by GHRH. Positive GHRH immunostaining in the NET tissue confirms the diagnosis. Distinguishing between pituitary (somatotroph) hyperplasia secondary to ectopic GHRH and pituitary adenoma is difficult and requires specialist neuroradiology input and consideration, especially in the MEN1 setting. It is important to note that the vast majority of GHRH-secreting tumours (lung, pancreas, phaeochromocytoma) are expected to be visible on cross-sectional imaging (median diameter 55 mm) (1). Therefore, we suggest that a chest X-ray and an abdominal ultrasound checking the adrenal glands and the pancreas should be included in the routine work-up of newly diagnosed acromegaly patients.

A narrative review of multiple endocrine neoplasia syndromes: genetics, clinical features, imaging findings, and diagnosis

Objective

We aimed to provide ideas for clinicians, especially radiologists, for the diagnosis of multiple endocrine neoplasia (MEN) syndromes.

Background

MEN syndromes include MEN1, MEN2, and MEN4 and usually involve 2 or more endocrine tumors. The MEN syndromes are a group of euchromatic dominant genetic diseases, and the main genes involved include MEN1 (MEN1), RET (MEN2), and CDKN1B (MEN4).

Methods

In this article, involving 8 cases (4 cases of MEN1, 2 cases of MEN2A, 1 case of MEN2B, 1 case of MEN4) from our center, we introduced the disease spectrum, clinical manifestations (especially imaging findings), and related genes involved in each type of MEN syndromes. We also discussed the differential diagnosis between MEN and sporadic tumors and emphasized that MEN should be screened and the relevant required examinations.

Conclusions

Considering that MEN syndromes involve multiple endocrine gland tumors and nonendocrine organ diseases, it is very important to identify potential patients early and perform multiple examinations on them, including biochemical and multitype, and multisite imaging examinations according to the disease spectrum of each type. Considering that this is a group of genetic diseases, both interviewing patients about their family history and genetic testing are also very important. Only in this way can a comprehensive and accurate diagnosis be made, enabling patients to receive appropriate treatment and improve their prognosis.

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 Profile and Mutations Associated with Multiple Endocrine Neoplasia-Type1 (MEN1) and Their First-Degree Relatives at Risk of Developing MEN1: A Prospective Study

Multiple Endocrine Neoplasia type-1 (MEN1) is an autosomal dominant disorder with a combined occurrence of tumours of parathyroid glands, pancreatic islets, and anterior pituitary. About 90% of these patients carry mutations in the MEN1 gene, though the spectrum is not well defined in India. Forty clinically suspected cases of MEN1 were enrolled prospectively over six years; 32 patients (23 index-cases and nine affected relatives) with≥2 classical endocrine tumours of MEN1 were considered definite, and eight were categorised as 'MEN1-like'. Details of their clinical presentation, treatment and mutational analysis including MEN1 gene, 3' and 5' untranslated regions (UTR) of MEN1, CDKN1B, and CaSR genes were collated. Asymptomatic first-degree relatives were also screened. Among the 32 definite MEN1 patients, all had primary hyperparathyroidism, 22 (68.7%) had gastroentero-pancreatic neuroendocrine tumours, and 21 (66%) had pituitary adenoma. Of the 23 definite index-cases, 13 (56.5%) carried mutations in the MEN1 gene. Five of nine affected first-degree relatives (55.5%), and four of 10 asymptomatic relatives (40%) also had MEN1 mutations. Seven of 10 MEN1 mutation-negative definite index-cases harboured p.V109G polymorphism in the CDKN1B gene. All eight MEN1-like cases were negative for mutations and large deletions in MEN1, mutations in 3' and 5' UTR of MEN1, CaSR and CDKN1B genes. The study has helped to clearly document the pattern of mutations among Indian MEN1 patients. However, the absence of MEN1 mutation in ~44% of cases and the presence of p.V109G polymorphism in CDKN1B gene raise the question whether such polymorphisms could independently contribute to pathogenesis.

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.

Heterogeneity of the Clinical Presentation of the MEN1 LRG_509 c.781C>T (p.Leu261Phe) Variant Within a Three-Generation Family

Multiple neuroendocrine neoplasia type 1 (MEN1) is a rare genetic disorder with an autosomal dominant inheritance, predisposing carriers to benign and malignant tumors. The phenotype of MEN1 syndrome varies between patients in terms of tumor localization, age of onset, and clinical aggressiveness, even between affected members within the same family. We describe a heterogenic phenotype of the MEN1 variant c.781C>T (LRG_509t1), which was previously reported only once in a family with isolated hyperparathyroidism. A heterozygous missense variant in exon 4 of the gene was identified in the sequence of the MEN1 gene, i.e., c.781C>T, leading to the amino acid change p.Leu261Phe in a three-generation family. In the screened family, 5/6 affected members had already developed hyperparathyroidism. In the index patient and two other family members, an aggressive course of pancreatic neuroendocrine tumor (insulinoma and non-functioning neuroendocrine tumors) with dissemination was diagnosed. In the index patient, late diagnosis and slow progression of the disseminated neuroendocrine tumor have been observed (24 years of follow-up). The very rare variant of MEN1, LRG_509t1 c.781C>T /p.Leu261Phe (LRG_509p1), diagnosed within a three-generation family has a heterogenic clinical presentation. Further follow-up of the family members should be carried out to confirm the spectrum and exact time of clinical presentation.

Genetics of Acromegaly and Gigantism

Growth hormone (GH)-secreting pituitary tumours represent the most genetically determined pituitary tumour type. This is true both for germline and somatic mutations. Germline mutations occur in several known genes (AIP, PRKAR1A, GPR101, GNAS, MEN1, CDKN1B, SDHx, MAX) as well as familial cases with currently unknown genes, while somatic mutations in GNAS are present in up to 40% of tumours. If the disease starts before the fusion of the epiphysis, then accelerated growth and increased final height, or gigantism, can develop, where a genetic background can be identified in half of the cases. Hereditary GH-secreting pituitary adenoma (PA) can manifest as isolated tumours, familial isolated pituitary adenoma (FIPA) including cases with AIP mutations or GPR101 duplications (X-linked acrogigantism, XLAG) or can be a part of systemic diseases like multiple endocrine neoplasia type 1 or type 4, McCune-Albright syndrome, Carney complex or phaeochromocytoma/paraganglioma-pituitary adenoma association. Family history and a search for associated syndromic manifestations can help to draw attention to genetic causes; many of these are now tested as part of gene panels. Identifying genetic mutations allows appropriate screening of associated comorbidities as well as finding affected family members before the clinical manifestation of the disease. This review focuses on germline and somatic mutations predisposing to acromegaly and gigantism.

Expression of additional transcription factors is of prognostic value for aggressive behavior of pituitary adenomas

OBJECTIVE

According to the latest WHO classification of tumors of endocrine organs in 2017, plurihormonal adenomas are subclassified by their transcription factor (TF) expression. In the group of plurihormonal adenomas with unusual immunohistochemical combinations (PAWUC), the authors identified a large fraction of adenomas expressing TFs for gonadotroph adenoma (TFGA) cells in addition to other TFs. The aim of this study was to compare clinicopathological parameters of PAWUC with TFGA expression to gonadotroph adenomas that only express TFGA.

METHODS

This retrospective single-center series comprises 73 patients with TFGA-positive pituitary adenomas (SF1, GATA3, estrogen receptor α): 22 PAWUC with TFGA (TFGA-plus group) and 51 with TFGA expression only (TFGA-only group). Patient characteristics, outcome parameters, rate of invasiveness (assessed by direct endoscopic inspection), and MIB1 and MGMT status were compared between groups.

RESULTS

Patients in the TFGA-plus group were significantly younger than patients in the TFGA-only group (age 46 vs 56 years, respectively; p = 0.007). In the TFGA-only group, pituitary adenomas were significantly larger (diameter 25 vs 18.3 mm, p = 0.002). Intraoperatively, signs of invasiveness were significantly more common in the TFGA-plus group than in the TFGA-only group (50% vs 16%, p = 0.002). Gross-total resection was significantly lower in the nonfunctioning TFGA-plus group than in the TFGA-only group (44% vs 86%, p = 0.004). MIB1 and MGMT status showed no significant difference between groups.

CONCLUSIONS

These data suggest a more aggressive behavior of TFGA-positive adenomas if an additional TF is expressed within the tumor cells. Shorter radiographic surveillance and earlier consideration for retreatment should be recommended in these adenoma types.

Genomics and Epigenomics of Pituitary Tumors: What Do Pathologists Need to Know?

Molecular pathology has advanced our understanding of many tumors and offers opportunities to identify novel therapies. In the pituitary, the field has uncovered several genetic mutations that predispose to pituitary neuroendocrine tumor (PitNET) development, including MEN1, CDKN1B, PRKRIα, AIP, GPR101, and other more rare events; however, these genes are only rarely mutated in sporadic PitNETs. Recurrent genetic events in sporadic PitNETs include GNAS mutations in a subset of somatotroph tumors and ubiquitin-specific peptidase mutations (e.g., USP8, USP48) in some corticotroph tumors; to date, neither of these has resulted in altered management, and instead, the prognosis and management of PitNETs still rely more on cell type and subtype as well as local growth that determines surgical resectability. In contrast, craniopharyngiomas have either CTNNB1 or BRAF^V600E mutations that correlate with adamantinomatous or papillary morphology, respectively; the latter offers the opportunity for targeted therapy. DICER1 mutations are found in patients with pituitary blastoma. Epigenetic changes are implicated in the pathogenesis of the more common sporadic pituitary neoplasms including the majority of PitNETs and tumors of pituicytes.

The clinical aspects of pituitary tumour genetics

BACKGROUND

Pituitary tumours are usually benign and relatively common intracranial tumours, with under- and overexpression of pituitary hormones and local mass effects causing considerable morbidity and increased mortality. While most pituitary tumours are sporadic, around 5% of the cases arise in a familial setting, either isolated [familial isolated pituitary adenoma, related to AIP or X-linked acrogigantism], or in a syndromic disorder, such as multiple endocrine neoplasia type 1 or 4, Carney complex, McCune-Albright syndrome, phaeochromocytoma/paraganglioma with pituitary adenoma, DICER1 syndrome, Lynch syndrome, and USP8-related syndrome. Genetically determined pituitary tumours usually present at younger age and show aggressive behaviour, and are often resistant to different treatment modalities.

SUBJECT

In this practical summary, we take a practical approach: which genetic syndromes should be considered in case of different presentation, such as tumour type, family history, age of onset and additional clinical features of the patient.

CONCLUSION

The identification of the causative mutation allows genetic and clinical screening of relatives at risk, resulting in earlier diagnosis, a better therapeutic response and ultimately to better long-term outcomes.

[Genetic basis of Cushing's disease in children and targeted therapeutic future perspectives]

Cushing's disease (CD) is a multisystem disorder of a cortisol excess caused by ACTH -secreting pituitary tumor (corticotropinoma). CD in children is due to somatic or germline mutations with the late onset causing multiple endocrine tumors. If not treated, hypercortisolism leads to severe decrease in quality of life and life-threating conditions. The first-line treatment for CD is pituitary surgery, which might be followed by complications and relapse with necessity of additional surgery or initiations of second-line treatment. Recent studies of molecular basis of corticotropinoma development made it possible to employ medical therapy in CD. Understanding of corticotropinoma etiology and pathogenesis is an important part of education for pediatric endocrinologists since we need to keep in mind possibility of multisystem disorder in case of CD in children and because medical therapy might gain more important role for CD treatment in future.The most actual genetic aspects of corticotroph adenomas growth and the medical treatment opportunities are present in this review.

Update on the Genetics of Pituitary Tumors

Pituitary adenomas are common intracranial neoplasms, with diverse phenotypes. Most of these tumors occur sporadically and are not part of genetic disorders. Over the last decades numerous genetic studies have led to identification of somatic and germline mutations associated with pituitary tumors, which has advanced the understanding of pituitary tumorigenesis. Exploring the genetic background of pituitary neuroendocrine tumors can lead to early diagnosis associated with better outcomes, and their molecular mechanisms should lead to novel targeted therapies even for sporadic tumors. This article summarizes the genes and the syndromes associated with pituitary tumors.

Pediatric applications of Dotatate: early diagnostic and therapeutic experience

In recent years, new somatostatin receptor agents (SSTRs) have become available for diagnostic imaging and therapy in neuroendocrine tumors. The novel SSTR ligand DOTA-DPhel-Tyr3-octreotate (Dotatate) in particular can be linked with ⁶⁸Gallium for diagnostic imaging purposes, and with the β-emitter ¹⁷⁷Lutetium for radiotherapy in the setting of neuroendocrine tumors. Dotatate imaging offers distinct advantages in the evaluation of neuroendocrine tumors compared to standard techniques, including greater target-to-background ratio and lesion conspicuity, high sensitivity/specificity, improved spatial resolution with positron emission tomography (PET)/CT or PET/MR, and decreased radiation exposure. Although currently off-label in pediatrics, Dotatate theranostics in children are being explored, most notably in the setting of neuroblastoma and hereditary neuroendocrine syndromes. This article provides a multicenter case series of Dotatate imaging and therapy in pediatric patients in order to highlight the spectrum of potential clinical applications.

Aggressive pituitary tumors in the young and elderly

Aggressive pituitary tumors (APTs) represent rare pituitary adenomas (PAs) with local invasion of surrounding tissues, increased risk for multiple recurrence, rapid tumor growth, or resistance to standard therapies. The most common APTs in children and adolescents are giant prolactinomas and somatotropinomas. Few cases of Crooke's cell adenomas, silent corticotroph adenomas and pituitary carcinomas have also been reported in the literature. Pediatric patients with APTs have higher risk of harboring germline genetic defects, most commonly in the MEN1 and AIP genes. Since certain genetic defects confer a more aggressive behavior to PAs, genetic testing should be considered in tumors with young onset and positive family history. The management of pediatric APTs involves usually a combination of standard therapies (surgical, medical, radiation). Newer agents, such as temozolomide, have been used in few cases of pediatric pituitary tumors with promising results. In the elderly, PAs are more commonly non-functioning. Their management often poses dilemmas given the coexistence of age-related comorbidities. However, standard surgical treatment and temozolomide seem to be safe and well tolerated in elderly patients.

Potential markers of disease behavior in acromegaly and gigantism

Introduction: Acromegaly and gigantism entail increased morbidity and mortality if left untreated, due to the systemic effects of chronic GH and IGF-1 excess. Guidelines for the diagnosis and treatment of patients with GH excess are well established; however, the presentation, clinical behavior and response to treatment greatly vary among patients. Numerous markers of disease behavior are routinely used in medical practice, but additional biomarkers have been recently identified as a result of basic and clinical research studies.Areas covered: This review focuses on genetic, molecular and genomic features of patients with GH excess that have recently been linked to disease progression and response to treatment. A PubMed search was conducted to identify markers of disease behavior in acromegaly and gigantism. Markers already considered as part of routine studies in clinical care guidelines were excluded. Literature search was expanded for each marker identified. Novel markers not included or only partially covered in previously published reviews on the subject were prioritized.Expert opinion: Recognizing the most relevant markers of disease behavior may help the medical team tailoring the strategies for approaching each case of acromegaly and gigantism. This customized plan should make the evaluation, treatment and follow up process more efficient, greatly improving the patients' outcomes.

Multiple endocrine neoplasia: an update

The multiple endocrine neoplasia (MEN) syndromes include MEN1, MEN2 (formerly MEN2A), MEN3 (formerly MEN2B) and the recently identified MEN4. Clinical presentations are varied and often relate to the overproduction of specific hormones. Understanding the genetics of each syndrome assists in determining screening timelines. Treatments for each manifestation are dependent on location, risk of recurrence or malignancy, hormone excess and surgical morbidity. Multidisciplinary management should include geneticists, genetic counsellors, endocrinologists and endocrine surgeons.

La néoplasie endocrinienne multiple de type 1 : mise au point après le congrès de l’ENETS 2019

Multiple Endocrine Neoplasia Type 1 (NEM1) is related to mutations of the menin gene. It is an autosomal dominant disease. Its prevalence is about 1/30 000 with a hugh penetrance. There is no genotype-phenotype correlation. This hereditary syndrome is characterized by the presence of tumors of the endocrine system (parathyroid, endocrine pancreas, pituitary and adrenal gland). Other disorders have also been described (bronchial and thymic carcinoid tumor, breast cancer, skin lesions). Management must take into account the specificities of these pathologies in NEM1 compared to sporadic forms (young age at diagnosis, multiple lesions within the same gland, multi-focal disease). © 2019 Published by Elsevier Masson SAS. All rights reserved. Cet article fait partie du numéro supplément Les Must de l'Endocrinologie 2019 réalisé avec le soutien institutionnel de Ipsen-Pharma.

Clinical, Hormonal, and Neuroradiological Characteristics and Therapeutic Outcomes of Prolactinomas in Children and Adolescents at a Single Center

Background/Purpose: A prolactinoma is the most common pituitary adenoma, but it is relatively rare in childhood and adolescence. There is only limited research about the clinical spectrum, treatment, and outcomes of prolactinomas in childhood and adolescence. In this single-center cohort study, we assessed the clinical, hormonal, and neuroradiological characteristics and therapeutic outcomes of children and adolescents with prolactinomas. Methods: This retrospective cohort study included 25 patients with prolactinomas diagnosed before 19 years of age, who presented at Samsung Medical Center during a 15-year period (March 2005 to August 2019). Results: The median age at diagnosis was 16.9 (range 10.1-18.5) years, and 80% of the patients were female. The common clinical manifestations at diagnosis were galactorrhea (10/20, 50%) and amenorrhea (9/20, 45%) among females and visual field defects (3/5, 60%) and headaches (2/5, 40%) among males. In our cohort, macroadenomas accounted for 56% of cases, and the rate of overall responsiveness to dopamine agonists (DAs) was 56% (10/18). Male gender, the prolactin (PRL) level at diagnosis, and the presence of panhypopituitarism were positively correlated with maximum tumor diameter (r = 0.443, P = 0.026; r = 0.710, P < 0.001; and r = 0.623, P = 0.001, respectively). After the trans-sphenoidal approach (TSA), 53% (8/15) of patients showed normalization of the PRL level. Three patients, who underwent gamma knife surgery (GKS) owing to either resistance or intolerance to DAs or recurrence after the TSA, achieved a normal PRL level accompanied with marked tumor reduction and symptom remission. Conclusions: A macroprolactinoma is more prevalent than a microprolactinoma in children and adolescents than in adults. Male gender, increased PRL levels, and the presence of panhypopituitarism at diagnosis are closely related to macroprolactinomas in children and adolescents.

Phenotypes Associated With MEN1 Syndrome: A Focus on Genotype-Phenotype Correlations

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant inherited tumor syndrome, associated with parathyroid, pituitary, and gastro-entero-pancreatic (GEP) neuroendocrine tumors (NETs). MEN1 is usually consequent to different germline and somatic mutations of the MEN1 tumor suppressor gene, although phenocopies have also been reported. This review analyzed main biomedical databases searching for reports on MEN1 gene mutations and focused on aggressive and aberrant clinical manifestations to investigate the potential genotype-phenotype correlation. Despite efforts made by several groups, this link remains elusive to date and evidence that aggressive or aberrant clinical phenotypes may be related to specific mutations has been provided by case reports and small groups of MEN1 patients or families. In such context, a higher risk of aggressive tumor phenotypes has been described in relation to frameshift and non-sense mutations, and predominantly associated with aggressive GEP NETs, particularly pancreatic NETs. In our experience a novel heterozygous missense mutation at c.836C>A in exon 6 was noticed in a MEN1 patient operated for macro-prolactinoma, who progressively developed recurrent parathyroid adenomas, expanding gastrinomas and, long after the first MEN1 manifestation, a neuroendocrine uterine carcinoma. In conclusion, proof of genotype-phenotype correlation is limited but current evidence hints at the need for long-term interdisciplinary surveillance in patients with aggressive phenotypes and genetically confirmed MEN1.

The Genetics of Pituitary Adenomas

The genetic landscape of pituitary adenomas (PAs) is diverse and many of the identified cases remain of unclear pathogenetic mechanism. Germline genetic defects account for a small percentage of all patients and may present in the context of relevant family history. Defects in AIP (mutated in Familial Isolated Pituitary Adenoma syndrome or FIPA), MEN1 (coding for menin, mutated in Multiple Endocrine Neoplasia type 1 or MEN 1), PRKAR1A (mutated in Carney complex), GPR101 (involved in X-Linked Acrogigantism or X-LAG), and SDHx (mutated in the so called "3 P association" of PAs with pheochromocytomas and paragangliomas or 3PAs) account for the most common familial syndromes associated with PAs. Tumor genetic defects in USP8, GNAS, USP48 and BRAF are some of the commonly encountered tissue-specific changes and may explain a larger percentage of the developed tumors. Somatic (at the tumor level) genomic changes, copy number variations (CNVs), epigenetic modifications, and differential expression of miRNAs, add to the variable genetic background of PAs.

The Clinicopathological Spectrum of Acromegaly

BACKGROUND

Acromegaly results from a persistent excess in growth hormone with clinical features that may be subtle or severe. The most common cause of acromegaly is a pituitary tumor that causes excessive production of growth hormone (GH), and rare cases are due to an excess of the GH-releasing hormone (GHRH) or the ectopic production of GH.

OBJECTIVE

Discuss the different diseases that present with manifestations of GH excess and clinical acromegaly, emphasizing the distinct clinical and radiological characteristics of the different pathological entities.

METHODS

We performed a narrative review of the published clinicopathological information about acromegaly. An English-language search for relevant studies was conducted on PubMed from inception to 1 August 2019. The reference lists of relevant studies were also reviewed.

RESULTS

Pituitary tumors that cause GH excess have several variants, including pure somatotroph tumors that can be densely or sparsely granulated, or plurihormonal tumors that include mammosomatotroph, mixed somatotroph-lactotroph tumors and mature plurihomonal Pit1-lineage tumors, acidophil stem cell tumors and poorly-differentiated Pit1-lineage tumors. Each tumor type has a distinct pathophysiology, resulting in variations in clinical manifestations, imaging and responses to therapies.

CONCLUSION

Detailed clinicopathological information will be useful in the era of precision medicine, in which physicians tailor the correct treatment modality to each patient.

Genetics of Pituitary Tumours

Pituitary tumours are relatively common in the general population. Most often they occur sporadically, with somatic mutations accounting for a significant minority of somatotroph and corticotroph adenomas. Pituitary tumours can also develop secondary to germline mutations as part of a complex syndrome or as familial isolated pituitary adenomas. Tumours occurring in a familial setting may present at a younger age and can behave more aggressively with resistance to treatment. This chapter will focus on the genetics and molecular pathogenesis of pituitary tumours.