MEN4 and CDKN1B mutations: the latest of the MEN syndromes

Differences in the mutational landscape of clonal hematopoiesis of indeterminate potential among Races and between Male and Female patients with cancer

Clonal hematopoiesis of indeterminate potential (CHIP) has emerged as a significant precursor to hematological malignancies and is associated with several age-related diseases. We leveraged public data to explore differences in the mutational landscape of CHIP between males and females and across diverse racial populations. DNMT3A mutations were substantially more prevalent in females than in males (38.94% vs. 31.37%, p-value: <0.001, q-value: <0.001). While ASXL1 mutations were more frequent in males than females (5.82% vs 2.69%, p-value: <0.001, q-value: <0.001). In the racial cohorts with sufficient sample sizes, STAT5B and CSF1R mutations were most frequent in Asian (1.40% and 0.84%), followed by Black (0.98% and 0.24%) and White populations (0.29% and 0.09%), (p-value: 0.001 and 0.001, q-value: 0.023 and 0.023). Several other CHIP mutations were enriched in Black: RARA, SMAD2, CDKN1B, CENPA, CTLA4, EIF1AX, ELF3, MSI1, MYC, SOX17, AURKA. On the other hand, H3C1, H3C4, MYCL were enriched in the Asian cohort. Our analysis highlights sex and racial differences in the CHIP mutations among patients with cancer. As CHIP continues to gain recognition as a critical precursor to malignancies and other diseases, understanding how these differences contribute to CHIP underlying mechanisms and clinical implications is critical.

Beyond MEN1, When to Think About MEN4? Retrospective Study on 5600 Patients in the French Population and Literature Review

CONTEXT

Germline CDKN1B variants predispose patients to multiple endocrine neoplasia type 4 (MEN4), a rare MEN1-like syndrome, with <100 reported cases since its discovery in 2006. Although CDKN1B mutations are frequently suggested to explain cases of genetically negative MEN1, the prevalence and phenotype of MEN4 patients is poorly known, and genetic counseling is unclear.

OBJECTIVE

To evaluate the prevalence of MEN4 in MEN1-suspected patients and characterize the phenotype of MEN4 patients.

DESIGN

Retrospective observational nationwide study. Narrative review of literature and variant class reassessment.

PATIENTS

We included all adult patients with class 3/4/5 CDKN1B variants identified by the laboratories from the French Oncogenetic Network on Neuroendocrine Tumors network between 2015 and 2022 through germline genetic testing for MEN1 suspicion. After class reassessment, we compared the phenotype of symptomatic patients with class 4/5 CDKN1B variants (ie, with genetically confirmed MEN4 diagnosis) in our series and in literature with 66 matched MEN1 patients from the UMD-MEN1 database.

RESULTS

From 5600 MEN1-suspected patients analyzed, 4 with class 4/5 CDKN1B variant were found (0.07%). They presented with multiple duodenal NET, primary hyperparathyroidism (PHPT) and adrenal nodule, isolated PHPT, PHPT, and pancreatic neuroendocrine tumor. We listed 29 patients with CDKN1B class 4/5 variants from the literature. Compared with matched MEN1 patients, MEN4 patients presented lower NET incidence and older age at PHPT diagnosis.

CONCLUSION

The prevalence of MEN4 is low. PHPT and pituitary adenoma represent the main associated lesions, NETs are rare. Our results suggest a milder and later phenotype than in MEN1. Our observations will help to improve genetic counseling and management of MEN4 families.

Molecular Classification of Gastrointestinal and Pancreatic Neuroendocrine Neoplasms: Are We Ready for That?

In the last two decades, the increasing availability of technologies for molecular analyses has allowed an insight in the genomic alterations of neuroendocrine neoplasms (NEN) of the gastrointestinal tract and pancreas. This knowledge has confirmed, supported, and informed the pathological classification of NEN, clarifying the differences between neuroendocrine carcinomas (NEC) and neuroendocrine tumors (NET) and helping to define the G3 NET category. At the same time, the identification genomic alterations, in terms of gene mutation, structural abnormalities, and epigenetic changes differentially involved in the pathogenesis of NEC and NET has identified potential molecular targets for precision therapy. This review critically recapitulates the available molecular features of digestive NEC and NET, highlighting their correlates with pathological aspects and clinical characteristics of these neoplasms and revising their role as predictive biomarkers for targeted therapy. In this context, the feasibility and applicability of a molecular classification of gastrointestinal and pancreatic NEN will be explored.

Hereditary Syndromes Associated with Pancreatic and Lung Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PanNETs) and lung NETs (LNETs) represent a rare but clinically significant subgroup of neoplasms. While the majority is sporadic, approximately 17% of PanNETs and a subset of LNETs develop in the context of monogenic familial tumor syndromes, especially multiple endocrine neoplasia type 1 (MEN1) syndrome. Other inherited syndromes associated with PanNETs include MEN4, von Hippel-Lindau (VHL) syndrome, neurofibromatosis type 1 (NF1), and tuberous sclerosis complex (TSC). These syndromes are highly penetrant and their clinical manifestations may vary even among members of the same family. They are attributed to genetic mutations involving key molecular pathways regulating cell growth, differentiation, and angiogenesis. Pancreatic NETs in hereditary syndromes are often multiple, develop at a younger age compared to sporadic tumors, and are associated with endocrine and nonendocrine tumors derived from multiple organs. Lung NETs are not as common as PanNETs and are mostly encountered in MEN1 syndrome and include typical and atypical lung carcinoids. Early detection of PanNETs and LNETs related to inherited syndromes is crucial, and specific follow-up protocols need to be employed to optimize diagnosis and management. Genetic screening is recommended in childhood, and diagnostic screening starts often in adolescence, even in asymptomatic mutation carriers. Optimal management and therapeutic decisions should be made in the context of a multidisciplinary team in specialized centers, whereas specific biomarkers aiming to identify patients denoted to follow a more aggressive course need to be developed.

Well-differentiated G1 and G2 pancreatic neuroendocrine tumors: a meta-analysis of published expanded DNA sequencing data

Introduction

Well-differentiated pancreatic neuroendocrine tumors (PNETs) can be non-functional or functional, e.g. insulinoma and glucagonoma. The majority of PNETs are sporadic, but PNETs also occur in hereditary syndromes, primarily multiple endocrine neoplasia type 1 (MEN1). The Knudson hypothesis stated a second, somatic hit in MEN1 as the cause of PNETs of MEN1 syndrome. In the recent years, reports on genetic somatic events in both sporadic and hereditary PNETs have emerged, providing a basis for a more detailed molecular understanding of the pathophysiology. In this systematic review and meta-analysis, we made a collation and statistical analysis of aggregated frequent genetic alterations and potential driver events in human grade G1/G2 PNETs.

Methods

A systematic search was performed in concordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) reporting guidelines of 2020. A search in Pubmed for published studies using whole exome, whole genome, or targeted gene panel (+400 genes) sequencing of human G1/G2 PNETs was conducted at the 25th of September 2023. Fourteen datasets from published studies were included with data on 221 patients and 225 G1/G2 PNETs, which were divided into sporadic tumors, and hereditary tumors with pre-disposing germline variants, and tumors with unknown germline status. Further, non-functioning and functioning PNETs were distinguished into two groups for pathway evaluation. The collated genetical analyses were conducted using the 'maftools' R-package.

Results

Sporadic PNETs accounted 72.0% (162/225), hereditary PNETs 13.3% (30/225), unknown germline status 14.7% (33/225). The most frequently altered gene was MEN1, with somatic variants and copy number variations in overall 42% (95/225); hereditary PNETs (germline variations in MEN1, VHL, CHEK2, BRCA2, PTEN, CDKN1B, and/or MUTYH) 57% (16/30); sporadic PNETs 36% (58/162); unknown germline status 64% (21/33). The MEN1 point mutations/indels were distributed throughout MEN1. Overall, DAXX (16%, 37/225) and ATRX-variants (12%, 27/225) were also abundant with missense mutations clustered in mutational hotspots associated with histone binding, and translocase activity, respectively. DAXX mutations occurred more frequently in PNETs with MEN1 mutations, p<0.05. While functioning PNETs shared few variated genes, non-functioning PNETs had more recurrent variations in genes associated with the Phosphoinositide 3-kinase, Wnt, NOTCH, and Receptor Tyrosine Kinase-Ras signaling onco-pathways.

Discussion

The somatic genetic alterations in G1/G2 PNETs are diverse, but with distinct differences between sporadic vs. hereditary, and functional vs. non-functional PNETs. Increased understanding of the genetic alterations may lead to identification of more drivers and driver hotspots in the tumorigenesis in well-differentiated PNETs, potentially giving a basis for the identification of new drug targets. (Funded by Novo Nordisk Foundation, grant number NNF19OC0057915).

Syndromic MEN1 parathyroid adenomas consist of both subclonal nodules and clonally independent tumors

Primary hyperparathyroidism with parathyroid tumors is a typical manifestation of Multiple Endocrine Neoplasia Type 1 (MEN1) and is historically termed "primary hyperplasia". Whether these tumors represent a multi-glandular clonal disease or hyperplasia has not been robustly proven so far. Loss of Menin protein expression is associated with inactivation of both alleles and a good surrogate for a MEN1 gene mutation. The cyclin-dependent kinase inhibitor 1B (CDKN1B) gene is mutated in MEN4 and encodes for protein p27 whose expression is poorly studied in the syndromic MEN1 setting.Here, we analyzed histomorphology and protein expression of Menin and p27 in parathyroid adenomas of 25 patients of two independent, well-characterized MEN1 cohorts. The pattern of loss of heterozygosity (LOH) was assessed by fluorescence in situ hybridization (FISH) in one MEN1-associated parathyroid adenoma. Further, next-generation sequencing (NGS) was performed on eleven nodules of four MEN1 patients.Morphologically, the majority of MEN1 adenomas consisted of multiple distinct nodules, in which Menin expression was mostly lost and p27 protein expression reduced. FISH analysis revealed that most nodules exhibited MEN1 loss, with or without the loss of centromere 11. NGS demonstrated both subclonal evolution and the existence of clonally unrelated tumors.Syndromic MEN1 parathyroid adenomas therefore consist of multiple clones with subclones, which supports the current concept of the novel WHO classification of parathyroid tumors (2022). p27 expression was lost in a large fraction of MEN1 parathyroids and must therefore be used with caution in suggesting MEN4.

Familial states of primary hyperparathyroidism: an update

BACKGROUND

Familial primary hyperparathyroidism (PHPT) includes syndromic and non-syndromic disorders. The former are characterized by the occurrence of PHPT in association with extra-parathyroid manifestations and includes multiple endocrine neoplasia (MEN) types 1, 2, and 4 syndromes, and hyperparathyroidism-jaw tumor (HPT-JT). The latter consists of familial hypocalciuric hypercalcemia (FHH) types 1, 2 and 3, neonatal severe primary hyperparathyroidism (NSHPT), and familial isolated primary hyperparathyroidism (FIHP). The familial forms of PHPT show different levels of PHPT penetrance, developing earlier and with multiglandular involvement compared to sporadic counterpart. All these diseases exhibit Mendelian inheritance patterns, and for most of them, the genes responsible have been identified. DNA testing for predisposing mutations is helpful in index cases or in individuals with a high suspicion of the disease. Early recognition of hereditary disorders of PHPT is of great importance for the best clinical and surgical approach. Genetic testing is useful in routine clinical practice because it will also involve appropriate screening for extra-parathyroidal manifestations related to the syndrome as well as the identification of asymptomatic carriers of the mutation.

PURPOSE

The aim of the review is to discuss the current knowledge on the clinical and genetic profile of these disorders along with the importance of genetic testing in clinical practice.

PDP type brain tumor in association with multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant syndrome caused by inactivating pathogenic variants in the tumor suppressor gene menin 1 on chromosome 11q13 (Falchetti et al., 2009). The syndrome is characterized by neoplasia in two or more endocrine glands and has a high degree of penetrance. Pathogenic germline multiple neoplasia type 1 variants primarily result in neoplasia affecting the parathyroid glands, the pancreatic islet cells, and the anterior pituitary in combination. Primary hyperparathyroidism is the most common pathological manifestation of the syndrome, followed by pancreatic neuroendocrine tumors. Important genetic confirmation has been provided showing that ependymoma should be considered as a neoplasm that can occur in patients with MEN1 (Kato et al., 1996; Cuevas-Ocampo et al., 2017). The biphasic histopathological tumor entity shown in the present case we name Pleomorphic Xanthoastocytoma grade 3 differential pathology (PDP) in association with Multiple Endocrine Neoplasia type 1. This MEN1 associated tumor subtype is an extension of the findings on MEN1 associated ependymoma, where we show that the clinical phenotype itself may potentially be triggered by a frameshift germline pathogenic variant for the MEN1 gene, in combination with cyclin-dependent kinase inhibitor 1B gene germline variant and cyclin dependent kinase inhibitor 2A somatic deletion downstream of menin.

Molecular pathology of endocrine gland tumors: genetic alterations and clinicopathologic relevance

Tumors of the endocrine glands are common. Knowledge of their molecular pathology has greatly advanced in the recent past. This review covers the main molecular alterations of tumors of the anterior pituitary, thyroid and parathyroid glands, adrenal cortex, and adrenal medulla and paraganglia. All endocrine gland tumors enjoy a robust correlation between genotype and phenotype. High-throughput molecular analysis demonstrates that endocrine gland tumors can be grouped into molecular groups that are relevant from both pathologic and clinical point of views. In this review, genetic alterations have been discussed and tabulated with respect to their molecular pathogenetic role and clinicopathologic implications, addressing the use of molecular biomarkers for the purpose of diagnosis and prognosis and predicting response to molecular therapy. Hereditary conditions that play a key role in determining predisposition to many types of endocrine tumors are also discussed.

Multiple endocrine neoplasia type 4 (MEN4): a thorough update on the latest and least known men syndrome

PURPOSE

Multiple endocrine neoplasia type 4 (MEN4) is a rare multiglandular endocrine neoplasia syndrome, associated with a wide tumor spectrum but hallmarked by primary hyperparathyroidism, which represents the most common clinical feature, followed by pituitary (functional and non-functional) adenomas, and neuroendocrine tumors. MEN4 clinically overlaps MEN type 1 (MEN1) but differs from it for milder clinical features and an older patient's age at onset. The underlying mutated gene, CDKN1B, encodes the cell cycle regulator p27, implicated in cellular proliferation, motility and apoptosis. Given the paucity of MEN4 cases described in the literature, possible genotype-phenotype correlations have not been thoroughly assessed, and specific clinical recommendations are lacking. The present review provides an extensive overview of molecular genetics and clinical features of MEN4, with the aim of contributing to delineate peculiar strategies for clinical management, screening and follow-up of the last and least known MEN syndrome.

METHODS

A literature search was performed through online databases like MEDLINE and Scopus.

CONCLUSIONS

MEN4 is much less common that MEN1, tend to present later in life with a more indolent course, although involving the same primary organs as MEN1. As a consequence, MEN4 patients might need specific diagnostic and therapeutic approaches and a different strategy for screening and follow-up. Further studies are needed to assess the real oncological risk of MEN4 carriers, and to establish a standardized screening protocol. Furthermore, a deeper understanding of molecular genetics of MEN4 is needed in order to explore p27 as a novel therapeutic target.

Update on Current Evidence for the Diagnosis and Management of Nonfunctioning Pituitary Neuroendocrine Tumors

Pituitary neuroendocrine tumors (PitNETs) are the third most frequently diagnosed intracranial tumors, with nonfunctioning PitNETs (nfPitNETs) accounting for 30% of all pituitary tumors and representing the most common type of macroPitNETs. NfPitNETs are usually benign tumors with no evidence of hormone oversecretion except for hyperprolactinemia secondary to pituitary stalk compression. Due to this, they do not typically present with clinical syndromes like acromegaly, Cushing's disease or hyperthyroidism and instead are identified incidentally on imaging or from symptoms of mass effects (headache, vision changes, apoplexy). With the lack of effective medical interventions, first-line treatment is transsphenoidal surgical resection, however, nfPitNETs often have supra- or parasellar extension, and total resection of the tumor is often not possible, resulting in residual tumor regrowth or reoccurrence. While functional PitNETs can be easily followed for recurrence using hormonal biomarkers, there is no similar parameter to predict recurrence in nfPitNETs, hence delaying early recognition and timely management. Therefore, there is a need to identify prognostic biomarkers that can be used for patient surveillance and as therapeutic targets. This review focuses on summarizing the current evidence on nfPitNETs, with a special focus on potential new biomarkers and therapeutics.

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.

Clinical Factors Predicting Multiple Endocrine Neoplasia Type 1 and Type 4 in Patients with Neuroendocrine Tumors

The aim of this study is to evaluate the predictive role of specific clinical factors for the diagnosis of Multiple Endocrine Neoplasia type-1 (MEN1) and type-4 (MEN4) in patients with an initial diagnosis of gastrointestinal, bronchial, or thymic neuroendocrine tumor (NET).

METHODS

Patients referred to the NET Unit between June 2021 and December 2022 with a diagnosis of NET and at least one clinical criterion of suspicion for MEN1 and MEN4 underwent molecular analysis of the MEN1 and CDKN1B genes. Phenotypic criteria were: (1) age ≤ 40 years; (2) NET multifocality; (3) MEN1/4-associated manifestations other than NETs; and (4) endocrine syndrome related to NETs or pituitary/adrenal tumors.

RESULTS

A total of 22 patients were studied. In 18 patients (81.8%), the first-level genetic test was negative (Group A), while four patients (25%) were positive for MEN1 (Group B). No patient was positive for MEN4. In Group A, 10 cases had only one clinical criterion, and three patients met three criteria. In Group B, three patients had three criteria, and one met all criteria.

CONCLUSION

These preliminary data show that a diagnosis of NET in patients with a negative family history is suggestive of MEN1 in the presence of ≥three positive phenotypic criteria, including early age, multifocality, multiple MEN-associated manifestations, and endocrine syndromes. This indication may allow optimization of the diagnosis of MEN in patients with NET.

Genetic and clinical screening for hereditary primary hyperparathyroidism in a large Chinese cohort: a single-center study

Primary hyperparathyroidism (PHPT) includes sporadic PHPT and hereditary PHPT. However, until now, there have been no exact data on the proportion and composition of hereditary PHPT in the Chinese PHPT population. This study aimed to clarify the proportion and composition of hereditary PHPT in patients at a large academic center in Beijing, China, and to analyze genotype-phenotype characteristics. A total of 394 newly diagnosed Han PHPT patients who consented to genetic screening were enrolled. Targeted next-generation sequencing (T-NGS) (including for MEN1, RET, CDKN1B, CaSR, HRPT2/CDC73, GNA11, AP2S1, GCM2), combined with MEN1-multiplex ligation-dependent probe amplification (MLPA) and CDC73-MLPA, was used for genetic screening. Diagnosis of hereditary PHPT was based on clinical manifestations, family history, and genetic screening. Thirty-seven pathogenic (P)/likely pathogenic (LP) variants were detected in 41 patients via T-NGS, and three patients carried long-range deletions of MEN1 or CDC73 detected by MLPA, with a variant detection rate of 11.2% (44/394). In total, 30 patients were clinically diagnosed with MEN1. Combined with genetic and clinical screening, the rate of hereditary PHPT in this study was 18.8% (74/394). For purposes of comparison, the rate of unequivocal nonhereditary PHPT was 66.5% (262/394); 14.7% (58/394) did not exhibit the clinical features of hereditary PHPT but carried variants of uncertain clinical significance and so could not be clearly categorized. Both the age at hospital visit (43.6 ± 14.0 versus 53.7 ± 14.9 years) and age at onset (35.4 ± 13.8 versus 50.6 ± 14.8 years) in the hereditary group (n = 74) were significantly lower than those in the nonhereditary group (n = 262). Higher levels of ionized calcium and serum β-CTX were observed in the hereditary group; proportions of parathyroid hyperplasia and multigland involvement were also higher. In addition to multigland disease and positive family history, it is recommended that patients with an age of onset less than 38 should be screened for hereditary forms. © 2023 American Society for Bone and Mineral Research (ASBMR).

Approach to the Patient With Prolactinoma

Prolactinomas are the most common pituitary tumor histotype, with microprolactinomas being prevalent in women and macroprolactinomas in men. Hyperprolactinemia is among the most common causes of hypogonadotropic hypogonadism in both sexes, prompting medical advice for hypogonadism (infertility, oligo-amenorrhea, impotence, osteoporosis/osteopenia) in both sexes, and for signs and symptoms of mass effects (hypopituitarism, visual loss, optic chiasm compression, cranial nerve deficits, headaches) predominantly in men. Diagnostic workup involves a single prolactin measurement and pituitary imaging, but some laboratory artifacts (ie, the "hook effect" and macroprolactin) can complicate or delay the diagnosis. The treatment of choice for prolactinomas is represented by dopamine agonists, mainly cabergoline, which are able to induce disease control, restore fertility in both sexes, and definitively cure one-third of patients, thus permitting treatment discontinuation. Pregnancy and menopause may promote spontaneous prolactin decline and anticipate cabergoline discontinuation in women. Surgery and/or radiotherapy are indicated in case of resistance to cabergoline not overcome by the increase in drug dose up to the maximally tolerated or the patient's personal choice of surgery. The evidence of resistance to cabergoline in invasive and proliferative tumors may indicate biological aggressiveness, thus requiring alternative therapeutic approaches mainly based on temozolomide use as monotherapy or combined with radiotherapy. In uncontrolled patients, new medical approaches (alternative hormonal treatments, cytotoxic drugs, peptide receptor radionuclide therapy, mTOR/Akt inhibitors, tyrosine kinase inhibitors, or immunotherapy) may be offered but the experience collected to date is still very scant. This article reviews different facets of prolactinomas and discusses approaches to the condition in more common clinical situations.

A pan-cancer analysis for the oncogenic role of cyclin-dependent kinase inhibitor 1B in human cancers

BACKGROUND

Human health and life are threatened by cancer with high morbidity and mortality worldwide. In many experiments, CDKN1B level is associated with cancer risk, Nevertheless, no pan-cancer analysis has been conducted on CDKN1B in human cancers.

METHODS

With the help of bioinformatics, a pan-cancer analysis was conducted on the expression levels of CDKN1B in cancer tissues and adjacent tissues from the TCGA, CPTAC and GEO databases. The CDKN1B expression levels in tumor patients was further validated using immunohistochemistry (IHC) and quantitative real-time PCR.

RESULTS

In the study, we first investigated the cancer-related roles of CDKN1B's in 40 tumors with malignancy. The CDKN1B gene encodes the p27^Kip1 protein, which can block the production cyclin-dependent kinase (CDK), which is obviously related to the function and survival of cancer cells and alters the prognosis of cancer patients. Furthermore, CDKN1B function requires both protein processing and RNA metabolism. Additionally, the elevated expression of the CDKN1B gene and protein was validated in several cancer tissues from the patients.

CONCLUSIONS

These results showed that the levels of CDKN1B were considerably different in a number of cancer tissues, offering a potential future target for cancer therapy.

Cutaneous lesions and other non-endocrine manifestations of Multiple Endocrine Neoplasia type 1 syndrome

Background

Multiple Endocrine Neoplasia type 1 is a rare genetic syndrome mainly caused by mutations of MEN1 gene and characterized by a combination of several endocrine and non-endocrine manifestations. The objective of this study was to describe cutaneous lesions and other non-endocrine manifestations of MEN1 in a cohort of patients with familial (F) and sporadic (S) MEN1, compare the prevalence of these manifestations between the two cohorts, and investigate the correlation with MEN1 mutation status.

Methods

We collected phenotypic and genotypic data of 185 patients with F-MEN1 and S-MEN1 followed from 1997 to 2022. The associations between F-MEN1 and S-MEN1 or MEN1 mutation-positive and mutation-negative patients and non-endocrine manifestations were determined using chi-square or Fisher's exact tests or multivariate exact logistic regression analyses.

Results

The prevalence of angiofibromas was significantly higher in F-MEN1 than in S-MEN1 in both the whole (p < 0.001) and index case (p = 0.003) cohorts. The prevalence of lipomas was also significantly higher in F-MEN1 than in S-MEN1 (p = 0.009) and in MEN1 mutation-positive than in MEN1 mutation-negative (p = 0.01) index cases. In the whole cohort, the prevalence of lipomas was significantly higher in MEN1 mutation-positive compared to MEN1 mutation-negative patients (OR = 2.7, p = 0.02) and in F-MEN1 than in S-MEN1 (p = 0.03), only after adjustment for age. No significant differences were observed for the other non-endocrine manifestations between the two cohorts. Hibernoma and collagenoma were each present in one patient (0.5%) and meningioma and neuroblastoma in 2.7% and 0.5%, respectively. Gastric leiomyoma was present in 1.1% of the patients and uterine leiomyoma in 14% of women. Thyroid cancer, breast cancer, lung cancer, basal cell carcinoma, melanoma, and colorectal cancer were present in 4.9%, 2.7%, 1.6%, 1.6%, 2.2%, and 0.5% of the whole series, respectively.

Conclusions

We found a significantly higher prevalence of angiofibromas and lipomas in F-MEN1 compared with S-MEN1 and in MEN1 mutation-positive compared to MEN1 mutation-negative patients. In patients with one major endocrine manifestation of MEN1 , the presence of cutaneous lesions might suggest the diagnosis of MEN1 and a possible indication for genetic screening.

Neuroendocrine Neoplasms of the Gastrointestinal Tract versus Neuroendocrine Neoplasms of the Gynaecological Tract-Comparison of the Risk Factors and Non-Surgical Treatment Efficacy

Neuroendocrine tumours of the gastrointestinal tract are rare. The incidence has increased in recent years due to improvements in diagnostic methods for detecting these lesions. These tumours have a poor prognosis, especially when detected at an advanced stage. The basis of the treatment is resection, and non-surgical treatments are also standard in the treatment process. The situation is similar in even rarer neuroendocrine tumours of the reproductive tract, which are associated with an equally poor prognosis. In this article, we focus on learning about the risk factors (including genetic mutations) that increase the risk of the disease and comparing the effectiveness of non-surgical treatments-chemotherapy, radiotherapy, peptide receptor radionuclide therapy, somatostatin analogues, and immunotherapy. The efficacy of these treatments varies, and immunotherapy appears to be a promising form of treatment; however, this requires further research.

An unusual presentation of papillary thyroid carcinoma: a case report

INTRODUCTION

Parathyroid carcinoma (PC) is exceptional cause of primary hyperparathyroidism (PHPT). It has an estimated prevalence of 0.3 to 5.6% and is rarely associated with non-medullary thyroid cancer.

OBSERVATION

We report a case of parathyroid carcinoma resulting in a hyperparathyroidism and revealing a papillary thyroid carcinoma and emphasize on the management particularities of this entity. A 37-year-old woman, with prolactin secreting pituitary microadenoma, presented with asthenia and bone pain. Laboratory findings were consistent with PHPT. Neck ultrasonography showed a 3 cm nodule adjacent to the right thyroid lobe with no abnormalities in the thyroid gland. Parathyroid scintigraphy showed a right inferior parathyroid adenoma. Because of the patient age and the decreased renal function, surgical treatment was required. During the intra-operative neck exploration, a juxta-thyroid tumoral right mass was strongly adherent to the right infra-hyoid muscle and the recurrent laryngeal nerve. The frozen examination of the mass demonstrated malignancy features suggesting a poorly differentiated thyroid carcinoma. Thus, a total thyroidectomy with bilateral central neck dissection was carried out. Final histopathological examination showed a 3.5 cm PC infiltrating the thyroid gland with a papillary thyroid microcarcinoma of the left thyroid lobe. External radiotherapy of the neck, indicated for PC, was performed 1 month after surgery. A radioactive iodine therapy was used 6 months postoperatively.

CONCLUSION

Despite its rarity, PC is to bear in mind in case of PHPT. The association between PC and differentiated thyroid carcinoma is not to be ignored.

Indications for genetic study in gastro-entero-pancreatic and thoracic neuroendocrine tumors

Gastro-entero-pancreatic (GEP-NET) and thoracic neuroendocrine tumours (NETs) are one of the most heritable groups of neoplasms in the body, being multiple endocrine neoplasia syndrome type 1 (MEN1), the genetic syndrome most frequently associated with this type of tumours. Moreover, Von Hippel Lindau syndrome, tuberous sclerosis, type 4 multiple neoplasia syndrome, and type 1 neurofibromatosis are associated with an increased risk of developing GEP-NETs. Another important aspect in GEP-NETs and thoracic NETs is the knowledge of the molecular background since the molecular profile of these tumours may have implications in the prognosis and in the response to specific treatments. This review summarizes the main indications for performing a genetic study in patients with GEP-NETs and thoracic NETs, and the methods used to carry it out. Moreover, it offers a description of the main hereditary syndromes associated with these NETs and their molecular background, as well as the clinical implications of the molecular profile.

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.

Multiple endocrine neoplasia type 4: a new member of the MEN family

OBJECTIVE

Multiple endocrine neoplasia type 4 (MEN4) is caused by a CDKN1B germline mutation first described in 2006. Its estimated prevalence is less than one per million. The aim of this study was to define the disease characteristics.

METHODS

A systematic review was performed according to the PRISMA 2020 criteria. A literature search from January 2006 to August 2022 was done using MEDLINE® and Web of ScienceTM.

RESULTS

Forty-eight symptomatic patients fulfilled the pre-defined eligibility criteria. Twenty-eight different CDKN1B variants, mostly missense (21/48, 44%) and frameshift mutations (17/48, 35%), were reported. The majority of patients were women (36/48, 75%). Men became symptomatic at a median age of 32.5 years (range 10-68, mean 33.7 ± 23), whereas the same event was recorded for women at a median age of 49.5 years (range 5-76, mean 44.8 ± 19.9) (P = 0.25). The most frequently affected endocrine organ was the parathyroid gland (36/48, 75%; uniglandular disease 31/36, 86%), followed by the pituitary gland (21/48, 44%; hormone-secreting 16/21, 76%), the endocrine pancreas (7/48, 15%), and the thyroid gland (4/48, 8%). Tumors of the adrenal glands and thymus were found in three and two patients, respectively. The presenting first endocrine pathology concerned the parathyroid (27/48, 56%) and the pituitary gland (11/48, 23%). There were one (27/48, 56%), two (13/48, 27%), three (3/48, 6%), or four (5/48, 10%) syn- or metachronously affected endocrine organs in a single patient, respectively.

CONCLUSION

MEN4 is an extremely rare disease, which most frequently affects women around 50 years of age. Primary hyperparathyroidism as a uniglandular disease is the leading pathology.

Neuroendocrine neoplasms in the context of inherited tumor syndromes: a reappraisal focused on targeted therapies

PURPOSE

Neuroendocrine neoplasms can occur as part of inherited disorders, usually in the form of well-differentiated, slow-growing tumors (NET). The main predisposing syndromes include: multiple endocrine neoplasias type 1 (MEN1), associated with a large spectrum of gastroenteropancreatic and thoracic NETs, and type 4 (MEN4), associated with a wide tumour spectrum similar to that of MEN1; von Hippel-Lindau syndrome (VHL), tuberous sclerosis (TSC), and neurofibromatosis 1 (NF-1), associated with pancreatic NETs. In the present review, we propose a reappraisal of the genetic basis and clinical features of gastroenteropancreatic and thoracic NETs in the setting of inherited syndromes with a special focus on molecularly targeted therapies for these lesions.

METHODS

Literature search was systematically performed through online databases, including MEDLINE (via PubMed), and Scopus using multiple keywords' combinations up to June 2022.

RESULTS

Somatostatin analogues (SSAs) remain the mainstay of systemic treatment for NETs, and radiolabelled SSAs can be used for peptide-receptor radionuclide therapy for somatostatin receptor (SSTR)-positive NETs. Apart of these SSTR-targeted therapies, other targeted agents have been approved for NETs: the mTOR inhibitor everolimus for lung, gastroenteropatic and unknown origin NET, and sunitinib, an antiangiogenic tyrosine kinase inhibitor, for pancreatic NET. Novel targeted therapies with other antiangiogenic agents and immunotherapies have been also under evaluation.

CONCLUSIONS

Major advances in the understanding of genetic and epigenetic mechanisms of NET development in the context of inherited endocrine disorders have led to the recognition of molecular targetable alterations, providing a rationale for the implementation of treatments and development of novel targeted therapies.

Germline CDKN1B variant type and site are associated with phenotype in MEN4

Multiple endocrine neoplasia 4 (MEN4) is a rare multiglandular endocrine neoplasia syndrome clinically hallmarked by primary hyperparathyroidism (PHPT), pituitary adenoma (PitAd), and neuroendocrine tumors (NET), clinically overlapping MEN1. The underlying mutated gene - CDKN1B, encodes for the cell-cycle regulator p27. Possible genotype-phenotype correlations in MEN4 have not been thoroughly assessed. Prompted by the findings in three Israeli MEN4 kindreds, we performed a literature review on published and unpublished data from previously reported MEN4/CDKN1B cases. Univariate analysis analyzed time-dependent risks for developing PHPT, PitAd, or NET by variant type and position along the gene. Overall, 74 MEN4 cases were analyzed. PHPT risk was 53.4% by age 60 years (mean age at diagnosis age 50.6 ± 13.9 years), risk for PitAd was 23.2% and risk for NET was 16.2% (34.4 ± 21.4 and 52.9 ± 13.9 years, respectively). The frameshift variant p.Q107fs was the most common variant identified (4/41 (9.7%) kindreds). Patients with indels had higher risk for PHPT vs point mutations (log-rank, P = 0.029). Variants in codons 94-96 were associated with higher risk for PHPT (P < 0.001) and PitAd (P = 0.031). To conclude, MEN4 is clinically distinct from MEN1, with lower risk and older age for PHPT diagnosis. We report recurrent CDKN1B frameshift variants and possible genotype-phenotype correlations.

[MEN for multiple endocrin neoplasms: When evokate MEN? Update 2022]

Multiple endocrine neoplasia (MEN) are genetic predisposition syndromes to endocrine tumors including MEN1, MEN2 and exceptionally MEN4. MEN are transmitted in an autosomal dominant fashion with a high penetrance. Classically, there is no genotype/phenotype correlation for NEM1 whereas this is the case for NEM2. Patients with NEM1, linked to an inactivating mutation of the menin gene, may present with: primary hyperparathyroidism, pituitary adenoma, duodeno-pancreatic neuroendocrine tumors (NETs), bronchial tumors with an increased risk of thymoma, adrenal cortical tumors, an increased risk of breast cancer and characteristic skin involvement such as collagenomas, lentiginomas and an increased risk of skin cancer. These patients require at least annual follow-up. Screening of children is proposed from the age of 5 years. Patients with NEM2, linked to an activating mutation of the RET proto-oncogene, all present with medullary thyroid carcinoma (MTC) at a variable age depending on the genotype. Some patients present a pheochromocytoma (50 %) and hyperparathyroidism (20 %). Pediatric forms with aggressive CMT, ganglioneuromatosis and marfanoid syndrome exist (rare NEM2B). Some mutations are associated with a risk of aggressive CMT, justifying prophylactic thyroidectomy before 6 months of age. The age of genetic testing depends on the mutation subtype in the NEM2 parent. NEM4, related to a mutation in the CDKN1B gene, are rare, with a less well-known pathogenesis and their follow-up is not well codified.

Major Genetic Motifs in Pituitary Adenomas: A Practical Literature Update

BACKGROUND

The literature includes many studies examining the genetic abnormalities that influence pituitary adenomas (PAs). We aimed to state the collective knowledge on the genetic underpinnings of PAs by organizing, summarizing, and consolidating the literature to serve as a comprehensive review for scientists and clinicians of the most up-to-date information underlying the genetic landscape of PAs.

METHODS

The PubMed and Google Scholar databases were searched using multiple key words and combined Medical Subject Headings terms; only articles published in English between January 2000 and January 2022 were included. Articles in which the focus did not relate to genetics, that included mainly anecdotal evidence, or that were single case studies were eliminated.

RESULTS

PAs are one of the most common intracranial neoplasms. However, the genetic underpinnings for these tumors are not yet fully elucidated. There are several categories of PAs: clinically significant versus not clinically significant, functional versus nonfunctional, and germline-derived versus sporadic origin. Each of these disease subcategories is characterized by unique genetic aberrations. Recently, more genes and other types of genetic aberrations have been identified as possible causes of PAs, such as copy number variations and altered levels of microRNAs.

CONCLUSIONS

This review serves to consolidate and summarize the literature discussing the genetic motifs of PAs to help physicians and scientists deliver patient-centered therapies.

Risk Allele Frequency Analysis and Risk Prediction of Single-Nucleotide Polymorphisms for Prostate Cancer

The incidence of prostate cancer (PCa) varies by ethnicity. This study aimed to provide insights into the genetic cause of PCa, which can result in differences in incidence among individuals of diverse ancestry. We collected data on PCa-associated single-nucleotide polymorphisms (SNPs) from a genome-wide association study catalog. Fisher’s exact tests were used to analyze the significance of enrichment or depletion of the effect on the allele at a given SNP. A network analysis was performed based on PCa-related SNPs that showed significant differences among ethnicities. The SNP-based polygenic risk score (PRS) was calculated, and its correlation with PCa incidence was evaluated. European, African, and East Asian populations had different heatmap patterns. Calculated PRS from the allele frequencies of PCa was the highest among Africans, followed by Europeans, and was the lowest among East Asians. PRS was positively correlated with the incidence and mortality of PCa. Network analysis revealed that AR, CDKN1B, and MAD1L1 are genes related to ethnic differences in PCa. The incidence and mortality of PCa showed a strong correlation with PRS according to ethnicity, which may suggest the effect of genetic factors, such as the AR gene, on PCa pathogenesis.

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.

Genetics of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (pNETs) represent a relatively rare disease; however, the incidence has been increasing during the last 2 decades. Next generation sequencing has greatly increased our understanding of driver mutations in pNETs. Sporadic pNETs have consistently presented with mutations in MEN1, DAXX/ATRX, and genes related to the mammalian target of rapamycin pathway. Inherited pNETs have traditionally been associated with multiple endocrine neoplasia type 1, von Hippel-Lindau syndrome, neurofibromatosis type 1, and tuberous sclerosis complex. The current review expands on the existing knowledge and the relevant updates on the genetics of pNETs.

Diagnostic Strategies and Algorithms for Investigating Cancer Predisposition Syndromes in Children Presenting with Malignancy

Simple Summary

Here we provide an overview of several genetically determined conditions that predispose to the development of solid and hematologic malignancies in children. Diagnosing these conditions, whose prevalence is estimated around 10% in children with cancer, is useful to warrant personalized oncologic treatment and follow-up, as well as psychological and genetic counseling to these children and their families. We reviewed the most recent studies focusing on the prevalence of cancer predisposition syndromes in cancer-bearing children and the most-used clinical screening tools. Our work highlighted the value of clinical screening tools in the management of young cancer patients, especially in settings where genetic testing is not promptly accessible.

Abstract

In the past recent years, the expanding use of next-generation sequencing has led to the discovery of new cancer predisposition syndromes (CPSs), which are now known to be responsible for up to 10% of childhood cancers. As knowledge in the field is in constant evolution, except for a few “classic” CPSs, there is no consensus about when and how to perform germline genetic diagnostic studies in cancer-bearing children. Several clinical screening tools have been proposed to help identify the patients who carry higher risk, with heterogeneous strategies and results. After introducing the main clinical and molecular features of several CPSs predisposing to solid and hematological malignancies, we compare the available clinical evidence on CPS prevalence in pediatric cancer patients and on the most used decision-support tools in identifying the patients who could benefit from genetic counseling and/or direct genetic testing. This analysis highlighted that a personalized stepwise approach employing clinical screening tools followed by sequencing in high-risk patients might be a reasonable and cost-effective strategy in the care of children with cancer.

MEN4, the MEN1 Mimicker: A Case Series of three Phenotypically Heterogenous Patients With Unique CDKN1B Mutations

CONTEXT

Germline CDKN1B pathogenic variants result in multiple endocrine neoplasia type 4 (MEN4), an autosomal dominant hereditary tumor syndrome variably associated with primary hyperparathyroidism, pituitary adenoma, and duodenopancreatic neuroendocrine tumors.

OBJECTIVE

To report the phenotype of 3 unrelated cases each with a unique germline CDKN1B variant (of which 2 are novel) and compare these cases with those described in the current literature.

DESIGN/METHODS

Three case studies, including clinical presentation, germline, and tumor genetic analysis and family history.

SETTING

Two tertiary University Hospitals in Sydney, New South Wales, and 1 tertiary University Hospital in Canberra, Australian Capital Territory, Australia.

OUTCOME

Phenotype of the 3 cases and their kindred; molecular analysis and tumor p27kip1 immunohistochemistry.

RESULTS

Family A: The proband developed multiglandular primary hyperparathyroidism, a microprolactinoma and a multifocal nonfunctioning duodenopancreatic neuroendocrine tumor. Family B: The proband was diagnosed with primary hyperparathyroidism from a single parathyroid adenoma. Family C: The proband was diagnosed with a nonfunctioning pituitary microadenoma and ectopic Cushing's syndrome from an atypical thymic carcinoid tumor. Germline sequencing in each patient identified a unique variant in CDKN1B, 2 of which are novel (c.179G > A, p.Trp60*; c.475G > A, p.Asp159Asn) and 1 previously reported (c.374_375delCT, p.Ser125*).

CONCLUSIONS

Germline CDKN1B pathogenic variants cause the syndrome MEN4. The phenotype resulting from the 3 pathogenic variants described in this series highlights the heterogenous nature of this syndrome, ranging from isolated primary hyperparathyroidism to the full spectrum of endocrine manifestations. We report the first described cases of a prolactinoma and an atypical thymic carcinoid tumor in MEN4.

CDKN1B mutation analyses and biochemical characteristics in patients with symptomatic or asymptomatic primary hyperparathyroidism

Purpose: The aim of this study was to compare clinical, biochemical and treatment modalities of the patients with symptomatic and asymptomatic PHPT (primary hyperparathyroidism), and evaluate whether the CDKN1B mutation from these patients contributes to the pathogenesis of typical, sporadic parathyroid adenomas. Materials and Methods: In this prospective study 80 patients (66 women and 14 men, mean age 50.8 ± 12.01 years) with PHPT were enrolled. Biochemical and clinical information were collected on patients’ sex, age, biochemical examination and radiological findings (nuclear 99 mTc sestamibi scans scintigraphy, cervical ultrasound). CDKN1B sequencing, and DNA isolation was performed by using GeneMATRIX Quick Blood DNA Purification Kit. Selected primer of CDKN1BF (rs786201010, c.-456_-453delCCTT) (CAGGTTTGTTGGCAGCAGTA) and CDKN1BR (rs786201010, c.-456_-453delCCTT) (GGAGCCAAAAGACACAGACC) were amplified by polymerase chain reaction (PCR) (Solis Biodyne, Estonia). Results: A total of 80 patients diagnosed with PHPT were included, of which 22 were symptomatic. Serum calcium and 24-hour calcium excretion were significantly increased in patients with symptomatic PHTP. Serum PTH levels were similar between the two group. PHPT. CDKN1B mutation was not detected in any patients. Conclusion: Symptomatic patients were found to have elevated levels of calcium levels (hypercalcaemic), 24-hour urine calcium excretion and target organ damage (bone disease and nephrolithiasis). Independent of PTH levels, clinical signs and symptoms could be related with serum calcium parameters in these patients.

LINC00355 regulates p27KIP expression by binding to MENIN to induce proliferation in late-stage relapse breast cancer

Late-stage relapse (LSR) in patients with breast cancer (BC) occurs more than five years and up to 10 years after initial treatment and has less than 30% 5-year relative survival rate. Long non-coding RNAs (lncRNAs) play important roles in BC yet have not been studied in LSR BC. Here, we identify 1127 lncRNAs differentially expressed in LSR BC via transcriptome sequencing and analysis of 72 early-stage and 24 LSR BC patient tumors. Decreasing expression of the most up-regulated lncRNA, LINC00355, in BC and MCF7 long-term estrogen deprived cell lines decreases cellular invasion and proliferation. Subsequent mechanistic studies show that LINC00355 binds to MENIN and changes occupancy at the CDKN1B promoter to decrease p27Kip. In summary, this is a key study discovering lncRNAs in LSR BC and LINC00355 association with epigenetic regulation and proliferation in BC.

Pancreatic Neuroendocrine Neoplasms: Updates on Genomic Changes in Inherited Tumour Syndromes and Sporadic Tumours Based on WHO Classification

Pancreatic neuroendocrine neoplasms (PanNENs) are the neuroendocrine neoplasms with greatest rate of increase in incidence. Approximately 10% of PanNENs arise as inherited tumour syndromes which include multiple endocrine neoplasia type 1, multiple endocrine neoplasia type 4, von Hippel-Lindau syndrome, neurofibromatosis type1, tuberous sclerosis complex 1/2, Cowden syndrome, and Glucagon cell hyperplasia and neoplasia as well as familial insulinomatosis. In sporadic PanNENs, driver mutations in MEN1, DAXX/ATRX and mTOR pathway genes are associated with development and progression in pancreatic neuroendocrine tumours. The other changes are in VEGF pathway, Notch pathway, germline mutations in MUTYH, CHEK2, BRCA2, PHLDA3 as well as other genetic alterations. On the other hand, pancreatic neuroendocrine carcinomas share similar genetic alterations with ductal adenocarcinomas, e.g., TP53, RB1 or KRAS. In addition, microRNA and changes in immune microenvironment were noted in PanNENs. Updates on these genetic knowledges contribute to the development of management strategies for patients with PanNENs.

Overview of the 2022 WHO Classification of Familial Endocrine Tumor Syndromes

This review of the familial tumor syndromes involving the endocrine organs is focused on discussing the main updates on the upcoming fifth edition of the WHO Classification of Endocrine and Neuroendocrine Tumors. This review emphasizes updates on histopathological and molecular genetics aspects of the most important syndromes involving the endocrine organs. We describe the newly defined Familial Cancer Syndromes as MAFA-related, MEN4, and MEN5 as well as the newly reported pathological findings in DICER1 syndrome. We also describe the updates done at the new WHO on the syndromic and non-syndromic familial thyroid diseases. We emphasize the problem of diagnostic criteria, mention the new genes that are possibly involved in this group, and at the same time, touching upon the role of some immunohistochemical studies that could support the diagnosis of some of these conditions. As pathologists play an important role in identifying tumors within a familial cancer syndrome, we highlight the most important clues for raising the suspicious of a syndrome. Finally, we highlight the challenges in defining these entities as well as determining their clinical outcome in comparison with sporadic tumors. Instead of the usual subject review, we present the highlights of the updates on familial cancer syndromes by answering select questions relevant to practicing pathologists.

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.

A contemporary clinical approach to genetic testing for heritable hyperparathyroidism syndromes

PURPOSE

The improved access and affordability of next generation sequencing has facilitated the clinical use of gene panel testing to test concurrently patients for multiple heritable hyperparathyroidism syndromes. However, there is little guidance as to which patients should be selected for gene panel testing and which genes should be included in such panels. In this review, we provide a practical approach to considering, interpreting and managing genetic testing for familial primary hyperparathyroidism (PHPT) syndromes and familial hypocalciuric hypercalcaemia (FHH) in patients with PTH-dependent hypercalcaemia. We discuss known genes implicated in PHPT and FHH, testing criteria and yields, pre-test counselling, laboratory considerations, and post-test management.

METHODS

In addition to reviewing the literature, we conducted audits of local genetic testing data to examine the real-world yield of genetic testing in patients with PTH-dependent hypercalcaemia.

RESULTS

Our local audits revealed a positive genetic testing rate of 15-26% in patients with suspected hyperparathyroidism syndromes.

CONCLUSION

Based on the particular testing criteria met, affected patients should be tested for variants in the genes currently implicated in PHPT (MEN1, CDC73, RET, CDKN1B, GCM2, CASR) and/or FHH (CASR, GNA11, AP2S1). Patients should be provided with pre- and post-test counselling, including consideration of potential implications for family members.

Beyond the "3 Ps": A critical appraisal of the non-endocrine manifestations of multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1), an autosomal-dominantly inherited tumor syndrome, is classically defined by tumors arising from the "3 Ps": Parathyroids, Pituitary, and the endocrine Pancreas. From its earliest descriptions, MEN1 has been associated with other endocrine and non-endocrine neoplastic manifestations. High quality evidence supports a direct association between pathogenic MEN1 variants and neoplasms of the skin (angiofibromas and collagenomas), adipose tissue (lipomas and hibernomas), and smooth muscle (leiomyomas). Although CNS tumors, melanoma, and, most recently, breast cancer have been reported as MEN1 clinical manifestations, the published evidence to date is not yet sufficient to establish causality. Well-designed, multicenter prospective studies will help us to understand better the relationship of these tumors to MEN1, in addition to verifying the true prevalence and penetrance of the well-documented neoplastic associations. Nevertheless, patients affected by MEN1 should be aware of these non-endocrine manifestations, and providers should be encouraged always to think beyond the "3 Ps" when treating an MEN1 patient.

Case Report: New CDKN1B Mutation in Multiple Endocrine Neoplasia Type 4 and Brief Literature Review on Clinical Management

BACKGROUND

The fourth type of multiple endocrine neoplasia (MEN) is known as a rare variant of MEN presenting a MEN1-like phenotype and originating from a germline mutation in CDKN1B. However, due to the small number of cases documented in the literature, the peculiar clinical features of MEN4 are still largely unknown, and clear indications about the clinical management of these patients are currently lacking. In order to widen our knowledge on MEN4 and to better typify the clinical features of this syndrome, we present two more cases of subjects with MEN4, and through a review of the current literature, we provide some possible indications on these patients' management.

CASE PRESENTATION

The first report is about a man who was diagnosed with a metastatic ileal G2-NET at the age of 34. Genetic analysis revealed the mutation p.I119T (c.356T>C) of exon 1 of CDKN1B, a mutation already reported in the literature in association with early-onset pituitary adenomas. The second report is about a 76-year-old woman with a multifocal pancreatic G1-NET. Genetic analysis identified the CDKN1B mutation c.482C>G (p.S161C), described here for the first time in association with MEN4 and currently classified as a variant of uncertain significance. Both patients underwent biochemical and imaging screening for MEN1-related diseases without any pathological findings.

CONCLUSIONS

According to the cases reported in the literature, hyperparathyroidism is the most common clinical feature of MEN4, followed by pituitary adenoma and neuroendocrine tumors. However, MEN4 appears to be a variant of MEN with milder clinical features and later onset. Therefore, these patients might need a different and personalized approach in clinical management and a peculiar screening and follow-up strategy.

Cell-Free DNA and Clinical Characteristics in Patients with Small Intestinal or Pancreatic Neuroendocrine Tumors

INTRODUCTION

Neuroendocrine tumors (NETs) are rare and characterized by a heterogeneous clinical course and an unmet need for better prognostic markers. Plasma cell-free DNA (cfDNA) has prognostic value in other malignancies but is not previously investigated in NETs. We studied cfDNA levels in patients with mainly low-grade small intestinal NET -(siNET) or pancreatic NET (pNET) and evaluated the prognostic potential of cfDNA.

MATERIALS AND METHODS

We included 70 NET patients, siNET (n = 50) and pNET (n = 20). Plasma cfDNA levels were determined by droplet digital PCR for the beta-2-microglobulin gene every 6 months during a period of 3 years, including in a subgroup of 19 patients during peptide receptor radionuclide therapy (PRRT) therapy.

RESULTS

cfDNA levels were higher in both siNET and pNET compared to a previously established healthy cohort (p < 0.0001). -cfDNA levels did not predict overall survival (crude hazard ratio [HR] 0.95 [0.57-1.58], p = 0.837, adjusted for smoking status HR 0.77 [0.51-1.17], p = 0.22). The impact of cfDNA level on progression-free survival showed different trends in siNET and pNET. There was no effect of PRRT treatment on cfDNA levels and no difference in cfDNA levels between patients with and without progressive disease after PRRT (ANOVA p = 0.66). cfDNA levels were significantly higher in never-smokers and previous smokers than in current smokers (p = 0.029).

DISCUSSION/CONCLUSION

cfDNA levels are higher in NET patients than in healthy controls; however, there was no association with prognosis, and cfDNA levels were unaffected by PRRT. Our observations suggest that cfDNA levels are not associated with the disease course in low-grade NET in contrast to other malignancies.

Pituitary Tumors: Genetic and Molecular Factors Underlying Pathogenesis and Clinical Behavior

Pituitary neuroendocrine tumors (PitNETs) are the most common intracranial neoplasms. Although generally benign, they can show a clinically aggressive course, with local invasion, recurrences, and resistance to medical treatment. No universally accepted biomarkers of aggressiveness are available yet, and predicting clinical behavior of PitNETs remains a challenge. In rare cases, the presence of germline mutations in specific genes predisposes to PitNET formation, as part of syndromic diseases or familial isolated pituitary adenomas, and associates to more aggressive, invasive, and drug-resistant tumors. The vast majority of cases is represented by sporadic PitNETs. Somatic mutations in the α subunit of the stimulatory G protein gene (gsp) and in the ubiquitin-specific protease 8 (USP8) gene have been recognized as pathogenetic factors in sporadic GH- and ACTH-secreting PitNETs, respectively, without an association with a worse clinical phenotype. Other molecular factors have been found to significantly affect PitNET drug responsiveness and invasive behavior. These molecules are cytoskeleton and/or scaffold proteins whose alterations prevent proper functioning of the somatostatin and dopamine receptors, targets of medical therapy, or promote the ability of tumor cells to invade surrounding tissues. The aim of the present review is to provide an overview of the genetic and molecular alterations that can contribute to determine PitNET clinical behavior. Understanding subcellular mechanisms underlying pituitary tumorigenesis and PitNET clinical phenotype will hopefully lead to identification of new potential therapeutic targets and new markers predicting the behavior and the response to therapeutic treatments of PitNETs.

What Are the Place and Modalities of Surgical Management for Pancreatic Neuroendocrine Neoplasms? A Narrative Review

Pancreatic neuroendocrine neoplasms (panNENs) are a heterogeneous group of tumors derived from cells with neuroendocrine differentiation. They are considered malignant by default. However, their outcomes are variable depending on their presentation in the onset of hereditary syndromes, hormonal secretion, grading, and extension. Therefore, although surgical treatment has long been suggested as the only treatment of pancreatic neuroendocrine neoplasms, its modalities are an evolving landscape. For selected patients (small, localized, non-functional panNENs), a "wait and see" strategy is suggested, as it is in the setting of multiple neuroendocrine neoplasia type 1, but the accurate size cut-off remains to be established. Parenchyma-sparring pancreatectomy, aiming to limit pancreatic insufficiency, are also emerging procedures, which place beyond the treatment of insulinomas and small non-functional panNENs (in association with lymph node picking) remains to be clarified. Furthermore, giving the fact that the liver is generally the only metastatic site, surgery keeps a place of choice alongside medical therapies in the treatment of metastatic disease, but its modalities and extensions are still a matter of debate. This narrative review aims to describe the current recommended surgical management for pancreatic NENs and controversies in light of the actual recommendations and recent literature.

Growth hormone-releasing hormone-secreting pulmonary neuroendocrine tumor associated with pituitary hyperplasia and somatotropinoma

Acromegaly caused by ectopic growth hormone-releasing hormone (GHRH)-secreting tumor is exceedingly rare. We report a case of acromegaly secondary to GHRH secretion by an incidentally diagnosed pulmonary neuroendocrine tumor (NET) and review 47 similar cases in literature. A 22-year-old male patient presented with symptoms of pituitary apoplexy. Magnetic resonance imaging (MRI) showed apoplexy of a pituitary adenoma. Routinely prior to surgery, a chest radiography was performed which revealed a mass in the left lung. During investigation, the patient was diagnosed with metastatic GHRH-secreting pulmonary NET. In retrospect, it was noted that the patient had pituitary hyperplasia 20 months prior to the MRI which showed the presence of a pituitary adenoma. The histological findings confirmed somatotroph hyperplasia adjacent to somatotropinoma. This case suggests that GHRH secretion can be associated with pituitary hyperplasia, which may be followed by pituitary adenoma formation.

Parathyroid Tumors: Molecular Signatures

Parathyroid tumors are rare endocrine neoplasms affecting 0.1–0.3% of the general population, including benign parathyroid adenomas (PAs; about 98% of cases), intermediate atypical parathyroid adenomas (aPAs; 1.2–1.3% of cases) and malignant metastatic parathyroid carcinomas (PCs; less than 1% of cases). These tumors are characterized by a variable spectrum of clinical phenotypes and an elevated cellular, histological and molecular heterogeneity that make it difficult to pre-operatively distinguish PAs, aPAs and PCs. Thorough knowledge of genetic, epigenetic, and molecular signatures, which characterize different parathyroid tumor subtypes and drive different tumorigeneses, is a key step to identify potential diagnostic biomarkers able to distinguish among different parathyroid neoplastic types, as well as provide novel therapeutic targets and strategies for these rare neoplasms, which are still a clinical and therapeutic challenge. Here, we review the current knowledge on gene mutations and epigenetic changes that have been associated with the development of different clinical types of parathyroid tumors, both in familial and sporadic forms of these endocrine neoplasms.

Genetic Drivers of Ileal Neuroendocrine Tumors

Simple Summary

Although ileal neuroendocrine tumors are the most common tumors of the small intestine, they are not well-defined at the genetic level. Unlike most cancers, they have an unusually low number of mutations, and also lack recurrently mutated genes. Moreover ileal NETs have been difficult to study in the laboratory because there were no animal models and because cell lines were generally unavailable. But recent advances, including the first ileal NET mouse model as well as methods for culturing patient tumor samples, have been described and have already helped to identify IGF2 and CDK4 as two of the genetic drivers for this tumor type. These advances may help in the development of new treatments for patients.

Abstract

The genetic causes of ileal neuroendocrine tumors (ileal NETs, or I-NETs) have been a mystery. For most types of tumors, key genes were revealed by large scale genomic sequencing that demonstrated recurrent mutations of specific oncogenes or tumor suppressors. In contrast, genomic sequencing of ileal NETs demonstrated a distinct lack of recurrently mutated genes, suggesting that the mechanisms that drive the formation of I-NETs may be quite different than the cell-intrinsic mutations that drive the formation of other tumor types. However, recent mouse studies have identified the IGF2 and RB1 pathways in the formation of ileal NETs, which is supported by the subsequent analysis of patient samples. Thus, ileal NETs no longer appear to be a cancer without genetic causes.

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.