Insulinomatosis: new aspects.

Endogenous hyperinsulinemic hypoglycemia (EHH) is a rare condition with an incidence of approximately 4-6 per million person-years and comprises a group of disorders causing hyperinsulinemic hypoglycemia without exogenous administration of insulin or its secretagogues. In adults, most cases (approximately 90%) are secondary to a single insulinoma. Other causes include insulinoma in the context of multiple endocrine neoplasia type 1 (approximately 5% of cases) and non-insulinoma pancreatogenous hypoglycemia syndrome, which is estimated to account for 0.5-5% of all cases. Recently, an entity called insulinomatosis has been described as a novel cause of EHH in adults. The characteristic feature of insulinomatosis is the synchronous or metachronous occurrence of multiple pancreatic neuroendocrine tumors expressing exclusively insulin. While most cases arise sporadically, there is recent evidence that autosomal dominant inheritance of mutations in the v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog A (MAFA) gene can cause a familial form of insulinomatosis. In these families, EHH is paradoxically associated with the occurrence of diabetes mellitus within the same family. This review summarizes the current clinical, biochemical, imaging and genetic knowledge of this disease.

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.

Significant Benefits of AIP Testing and Clinical Screening in Familial Isolated and Young-onset Pituitary Tumors.

CONTEXT: Germline mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene are responsible for a subset of familial isolated pituitary adenoma (FIPA) cases and sporadic pituitary neuroendocrine tumors (PitNETs). OBJECTIVE: To compare prospectively diagnosed AIP mutation-positive (AIPmut) PitNET patients with clinically presenting patients and to compare the clinical characteristics of AIPmut and AIPneg PitNET patients. DESIGN: 12-year prospective, observational study. PARTICIPANTS & SETTING: We studied probands and family members of FIPA kindreds and sporadic patients with disease onset ≤18 years or macroadenomas with onset ≤30 years (n = 1477). This was a collaborative study conducted at referral centers for pituitary diseases. INTERVENTIONS & OUTCOME: AIP testing and clinical screening for pituitary disease. Comparison of characteristics of prospectively diagnosed (n = 22) vs clinically presenting AIPmut PitNET patients (n = 145), and AIPmut (n = 167) vs AIPneg PitNET patients (n = 1310). RESULTS: Prospectively diagnosed AIPmut PitNET patients had smaller lesions with less suprasellar extension or cavernous sinus invasion and required fewer treatments with fewer operations and no radiotherapy compared with clinically presenting cases; there were fewer cases with active disease and hypopituitarism at last follow-up. When comparing AIPmut and AIPneg cases, AIPmut patients were more often males, younger, more often had GH excess, pituitary apoplexy, suprasellar extension, and more patients required multimodal therapy, including radiotherapy. AIPmut patients (n = 136) with GH excess were taller than AIPneg counterparts (n = 650). CONCLUSIONS: Prospectively diagnosed AIPmut patients show better outcomes than clinically presenting cases, demonstrating the benefits of genetic and clinical screening. AIP-related pituitary disease has a wide spectrum ranging from aggressively growing lesions to stable or indolent disease course.

Tumour-infiltrating cytotoxic T lymphocytes in somatotroph pituitary neuroendocrine tumours.

INTRODUCTION: Somatotroph pituitary tumours are often resistant to first-generation somatostatin analogues and can invade the surrounding structures, limiting the chances of curative surgery. Recent studies suggested that the immune microenvironment and pro-angiogenic factors can influence neuroendocrine tumour prognosis. In this study, we aimed to investigate the prognostic role of immune cell-specific markers and endocan, a proteoglycan involved in neoangiogenesis and cell adhesion, in a cohort of acromegaly patients who underwent pituitary surgery as first-line treatment. SUBJECTS AND METHODS: Sixty four eligible subjects were identified. CD4+, CD8+ and CD68+ cells and endocan expression were evaluated by immunohistochemistry and results correlated with clinical and neuroradiological findings. Responsiveness to somatostatin analogues was assessed in patients with persistent disease following surgery. RESULTS: The number of CD8+ lymphocytes was significantly lower in tumours with cavernous sinus invasion (median 0.2/HPF, IQR: 2.2) compared with those without cavernous sinus invasion (median 2.4/HPF, IQR: 2.3; P = 0.04). Tumours resistant to first-generation somatostatin analogues had lower CD8+ lymphocytes (median 1/HPF, IQR: 2.4) compared with responders (median 2.4/HPF, IQR: 2.9; P = 0.005). CD4+ lymphocytes were observed sporadically. The number of CD68+ macrophages and the endothelial or tumour cell endocan expression did not differ based on tumour size, cavernous sinus invasion or treatment responsiveness. CONCLUSIONS: Our study suggests that a lower number of CD8+ lymphocytes is associated with cavernous sinus invasion and resistance to treatment with first-generation somatostatin analogues in acromegaly patients. These results highlight a potential role of the tumour immune microenvironment in determining the prognosis of somatotroph pituitary tumours.

Surgery, Octreotide, Temozolomide, Bevacizumab, Radiotherapy, and Pegvisomant Treatment of an AIP Mutation‒Positive Child.

CONTEXT: Inactivating germline mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene are linked to pituitary adenoma predisposition. Here, we present the youngest known patient with AIP-related pituitary adenoma. CASE DESCRIPTION: The patient presented at the age of 4 years with pituitary apoplexy and left ptosis with severe visual loss following a 1-year history of abdominal pain, headaches, and rapid growth. His IGF-1 level was 5× the upper limit of normal, and his random GH level was 1200 ng/mL. MRI showed a 43 × 24 × 35‒mm adenoma with suprasellar extension invading the left cavernous sinus (Knosp grade 4). After transsphenoidal surgery, histology showed a grade 2A sparsely granulated somatotropinoma with negative O6-methylguanine-DNA methyltransferase and positive vascular endothelial growth factor staining. Genetic testing identified a heterozygous germline nonsense AIP mutation (p.Arg81Ter). Exome sequencing of the tumor revealed that it had lost the entire maternal chromosome-11, rendering it hemizygous for chromosome-11 and therefore lacking functional copies of AIP in the tumor. He was started on octreotide, but because the tumor rapidly regrew and IGF-1 levels were unchanged, temozolomide was initiated, and intensity-modulated radiotherapy was administered 5 months after surgery. Two months later, bevacizumab was added, resulting in excellent tumor response. Although these treatments stabilized tumor growth over 4 years, IGF-1 was normalized only after pegvisomant treatment, although access to this medication was intermittent. At 3.5 years of follow-up, gamma knife treatment was administered, and pegvisomant dose increase was indicated. CONCLUSION: Multimodal treatment with surgery, long-acting octreotide, radiotherapy, temozolomide, bevacizumab, and pegvisomant can control genetically driven, aggressive, childhood-onset somatotropinomas.

Germline and mosaic mutations causing pituitary tumours: genetic and molecular aspects.

While 95% of pituitary adenomas arise sporadically without a known inheritable predisposing mutation, in about 5% of the cases they can arise in a familial setting, either isolated (familial isolated pituitary adenoma or FIPA) or as part of a syndrome. FIPA is caused, in 15-30% of all kindreds, by inactivating mutations in the AIP gene, encoding a co-chaperone with a vast array of interacting partners and causing most commonly growth hormone excess. While the mechanisms linking AIP with pituitary tumorigenesis have not been fully understood, they are likely to involve several pathways, including the cAMP-dependent protein kinase A pathway via defective G inhibitory protein signalling or altered interaction with phosphodiesterases. The cAMP pathway is also affected by other conditions predisposing to pituitary tumours, including X-linked acrogigantism caused by duplications of the GPR101 gene, encoding an orphan G stimulatory protein-coupled receptor. Activating mosaic mutations in the GNAS gene, coding for the Gα stimulatory protein, cause McCune-Albright syndrome, while inactivating mutations in the regulatory type 1α subunit of protein kinase A represent the most frequent genetic cause of Carney complex, a syndromic condition with multi-organ manifestations also involving the pituitary gland. In this review, we discuss the genetic and molecular aspects of isolated and syndromic familial pituitary adenomas due to germline or mosaic mutations, including those secondary to AIP and GPR101 mutations, multiple endocrine neoplasia type 1 and 4, Carney complex, McCune-Albright syndrome, DICER1 syndrome and mutations in the SDHx genes underlying the association of familial paragangliomas and phaeochromocytomas with pituitary adenomas.

Risk category system to identify pituitary adenoma patients with AIP mutations.

BACKGROUND: Predictive tools to identify patients at risk for gene mutations related to pituitary adenomas are very helpful in clinical practice. We therefore aimed to develop and validate a reliable risk category system for aryl hydrocarbon receptor-interacting protein (AIP) mutations in patients with pituitary adenomas. METHODS: An international cohort of 2227 subjects were consecutively recruited between 2007 and 2016, including patients with pituitary adenomas (familial and sporadic) and their relatives. All probands (n=1429) were screened for AIP mutations, and those diagnosed with a pituitary adenoma prospectively, as part of their clinical screening (n=24), were excluded from the analysis. Univariate analysis was performed comparing patients with and without AIP mutations. Based on a multivariate logistic regression model, six potential factors were identified for the development of a risk category system, classifying the individual risk into low-risk, moderate-risk and high-risk categories. An internal cross-validation test was used to validate the system. RESULTS: 1405 patients had a pituitary tumour, of which 43% had a positive family history, 55.5% had somatotrophinomas and 81.5% presented with macroadenoma. Overall, 134 patients had an AIP mutation (9.5%). We identified four independent predictors for the presence of an AIP mutation: age of onset providing an odds ratio (OR) of 14.34 for age 0-18 years, family history (OR 10.85), growth hormone excess (OR 9.74) and large tumour size (OR 4.49). In our cohort, 71% of patients were identified as low risk (<5% risk of AIP mutation), 9.2% as moderate risk and 20% as high risk (≥20% risk). Excellent discrimination (c-statistic=0.87) and internal validation were achieved. CONCLUSION: We propose a user-friendly risk categorisation system that can reliably group patients into high-risk, moderate-risk and low-risk groups for the presence of AIP mutations, thus providing guidance in identifying patients at high risk of carrying an AIP mutation. This risk score is based on a cohort with high prevalence of AIP mutations and should be applied cautiously in other populations.

Unusual AIP mutation and phenocopy in the family of a young patient with acromegalic gigantism.

Early-onset acromegaly causing gigantism is often associated with aryl-hydrocarbon-interacting receptor protein (AIP) mutation, especially if there is a positive family history. A15y male presented with tiredness and visual problems. He was 201 cm tall with a span of 217 cm. He had typical facial features of acromegaly, elevated IGF-1, secondary hypogonadism and a large macroadenoma. His paternal aunt had a history of acromegaly presenting at the age of 35 years. Following transsphenoidal surgery, his IGF-1 normalized and clinical symptoms improved. He was found to have a novel AIP mutation destroying the stop codon c.991T>C; p.*331R. Unexpectedly, his father and paternal aunt were negative for this mutation while his mother and older sister were unaffected carriers, suggesting that his aunt represents a phenocopy. LEARNING POINTS: Typical presentation for a patient with AIP mutation with excess growth and eunuchoid proportions.Unusual, previously not described AIP variant with loss of the stop codon.Phenocopy may occur in families with a disease-causing germline mutation.

MAFA missense mutation causes familial insulinomatosis and diabetes mellitus.

The ß-cell-enriched MAFA transcription factor plays a central role in regulating glucose-stimulated insulin secretion while also demonstrating oncogenic transformation potential in vitro. No disease-causing MAFA variants have been previously described. We investigated a large pedigree with autosomal dominant inheritance of diabetes mellitus or insulinomatosis, an adult-onset condition of recurrent hyperinsulinemic hypoglycemia caused by multiple insulin-secreting neuroendocrine tumors of the pancreas. Using exome sequencing, we identified a missense MAFA mutation (p.Ser64Phe, c.191C>T) segregating with both phenotypes of insulinomatosis and diabetes. This mutation was also found in a second unrelated family with the same clinical phenotype, while no germline or somatic MAFA mutations were identified in nine patients with sporadic insulinomatosis. In the two families, insulinomatosis presented more frequently in females (eight females/two males) and diabetes more often in males (12 males/four females). Four patients from the index family, including two homozygotes, had a history of congenital cataract and/or glaucoma. The p.Ser64Phe mutation was found to impair phosphorylation within the transactivation domain of MAFA and profoundly increased MAFA protein stability under both high and low glucose concentrations in ß-cell lines. In addition, the transactivation potential of p.Ser64Phe MAFA in ß-cell lines was enhanced compared with wild-type MAFA. In summary, the p.Ser64Phe missense MAFA mutation leads to familial insulinomatosis or diabetes by impacting MAFA protein stability and transactivation ability. The human phenotypes associated with the p.Ser64Phe MAFA missense mutation reflect both the oncogenic capacity of MAFA and its key role in islet ß-cell activity.

Novel Germline p.Gly42Val MEN1 Mutation in a Family with Multiple Endocrine Neoplasia Type 1 - Excellent Response of Prolactinoma to Cabergoline.

We report on a 27-year-old male patient presenting with renal colic secondary to hyperparathyroidism. Further investigations confirmed a diagnosis of type 1 multiple endocrine neoplasia and revealed a 2.0 cm pancreatic neuroendocrine tumour as well as a pituitary macroadenoma with significantly elevated prolactin levels. The patient underwent three-gland parathyroidectomy, a left pancreatectomy, and received dopamine agonist treatment. Genetic testing revealed a novel germline heterozygote missense mutation in the MEN1 gene (p.Gly42Val) which affects the Smad3 binding domain of the MENIN protein. The same mutation was found in the patient's mother, who on further testing was found to have hyperparathyroidism, a pituitary microadenoma and bilateral adrenal hyperplasia without pituitary or adrenal hormone excess. This case report raises the importance of genetic testing for MEN1 syndrome in a patient even when family history appears to be negative. Following genetic counselling, genetic cascade screening should be considered in family members to identify further gene carriers.

In-frame seven amino-acid duplication in AIP arose over the last 3000 years, disrupts protein interaction and stability and is associated with gigantism.

OBJECTIVE: Mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene are associated with pituitary adenoma, acromegaly and gigantism. Identical alleles in unrelated pedigrees could be inherited from a common ancestor or result from recurrent mutation events. DESIGN AND METHODS: Observational, inferential and experimental study, including: AIP mutation testing; reconstruction of 14 AIP-region (8.3 Mbp) haplotypes; coalescent-based approximate Bayesian estimation of the time to most recent common ancestor (tMRCA) of the derived allele; forward population simulations to estimate current number of allele carriers; proposal of mutation mechanism; protein structure predictions; co-immunoprecipitation and cycloheximide chase experiments. RESULTS: Nine European-origin, unrelated c.805_825dup-positive pedigrees (four familial, five sporadic from the UK, USA and France) included 16 affected (nine gigantism/four acromegaly/two non-functioning pituitary adenoma patients and one prospectively diagnosed acromegaly patient) and nine unaffected carriers. All pedigrees shared a 2.79 Mbp haploblock around AIP with additional haploblocks privately shared between subsets of the pedigrees, indicating the existence of an evolutionarily recent common ancestor, the 'English founder', with an estimated median tMRCA of 47 generations (corresponding to 1175 years) with a confidence interval (9-113 generations, equivalent to 225-2825 years). The mutation occurred in a small tandem repeat region predisposed to slipped strand mispairing. The resulting seven amino-acid duplication disrupts interaction with HSP90 and leads to a marked reduction in protein stability. CONCLUSIONS: The c.805_825dup allele, originating from a common ancestor, associates with a severe clinical phenotype and a high frequency of gigantism. The mutation is likely to be the result of slipped strand mispairing and affects protein-protein interactions and AIP protein stability.

PRKAR1A mutation causing pituitary-dependent Cushing disease in a patient with Carney complex.

CONTEXT: Carney complex (CNC) is an autosomal dominant condition caused, in most cases, by an inactivating mutation of the PRKAR1A gene, which encodes for the type 1 alpha regulatory subunit of protein kinase A. CNC is characterized by the occurrence of endocrine overactivity, myxomas and typical skin manifestations. Cushing syndrome due to primary pigmented nodular adrenocortical disease (PPNAD) is the most frequent endocrine disease observed in CNC. CASE DESCRIPTION: Here, we describe the first case of a patient with CNC and adrenocorticotropic hormone (ACTH)-dependent Cushing disease due to a pituitary corticotroph adenoma. Loss-of-heterozygosity analysis of the pituitary tumour revealed loss of the wild-type copy of PRKAR1A, suggesting a role of this gene in the pituitary adenoma development. CONCLUSION: PRKAR1A loss-of-function mutations can rarely lead to ACTH-secreting pituitary adenomas in CNC patients. Pituitary-dependent disease should be considered in the differential diagnosis of Cushing syndrome in CNC patients.

Gigantism: X-linked acrogigantism and GPR101 mutations.

X-linked acrogigantism (XLAG) is a recently identified condition of early-onset GH excess resulting from the germline or somatic duplication of the GPR101 gene on chromosome Xq26.3. Thirty patients have been formally reported so far. The disease affects mostly females, occurs usually sporadically, and is characterised by early onset and marked overgrowth. Most patients present with concomitant hyperprolactinaemia. Histopathology shows pituitary hyperplasia or pituitary adenoma with or without associated hyperplasia. XLAG-related pituitary adenomas present peculiar histopathological features that should contribute to raise the suspicion of this rare condition. Treatment is frequently challenging and multi-modal. While females present with germline mutations, the sporadic male patients reported so far were somatic mosaics with variable levels of mosaicism, although no differences in the clinical phenotype were observed between patients with germline or somatic duplication. The GPR101 gene encodes an orphan G protein-coupled receptor normally expressed in the central nervous system, and at particularly high levels in the hypothalamus. While the physiological function and the endogenous ligand of GPR101 are unknown, the high expression of GPR101 in the arcuate nucleus and the occurrence of increased circulating GHRH levels in some patients with XLAG, suggest that increased hypothalamic GHRH secretion could play a role in the pathogenesis of this condition. In this review, we summarise the published evidence on XLAG and GPR101 and discuss the results of recent studies that have investigated the potential role of GPR101 variants in the pathogenesis of pituitary adenomas.

Rapid Proteasomal Degradation of Mutant Proteins Is the Primary Mechanism Leading to Tumorigenesis in Patients With Missense AIP Mutations.

CONTEXT: The pathogenic effect of mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene (AIPmuts) in pituitary adenomas is incompletely understood. We have identified the primary mechanism of loss of function for missense AIPmuts. OBJECTIVE: This study sought to analyze the mechanism/speed of protein turnover of wild-type and missense AIP variants, correlating protein half-life with clinical parameters. DESIGN AND SETTING: Half-life and protein-protein interaction experiments and cross-sectional analysis of AIPmut positive patients' data were performed in a clinical academic research institution. PATIENTS: Data were obtained from our cohort of pituitary adenoma patients and literature-reported cases. INTERVENTIONS: Protein turnover of endogenous AIP in two cell lines and fifteen AIP variants overexpressed in HEK293 cells was analyzed via cycloheximide chase and proteasome inhibition. Glutathione-S-transferase pull-down and quantitative mass spectrometry identified proteins involved in AIP degradation; results were confirmed by coimmunoprecipitation and gene knockdown. Relevant clinical data was collected. MAIN OUTCOME MEASURES: Half-life of wild-type and mutant AIP proteins and its correlation with clinical parameters. RESULTS: Endogenous AIP half-life was similar in HEK293 and lymphoblastoid cells (43.5 and 32.7 h). AIP variants were divided into stable proteins (median, 77.7 h; interquartile range [IQR], 60.7-92.9 h), and those with short (median, 27 h; IQR, 21.6-28.7 h) or very short (median, 7.7 h; IQR, 5.6-10.5 h) half-life; proteasomal inhibition rescued the rapid degradation of mutant proteins. The experimental half-life significantly correlated with age at diagnosis of acromegaly/gigantism (r = 0.411; P = .002). The FBXO3-containing SKP1-CUL1-F-box protein complex was identified as the E3 ubiquitin-ligase recognizing AIP. CONCLUSIONS: AIP is a stable protein, driven to ubiquitination by the SKP1-CUL1-F-box protein complex. Enhanced proteasomal degradation is a novel pathogenic mechanism for AIPmuts, with direct implications for the phenotype.

Germline or somatic GPR101 duplication leads to X-linked acrogigantism: a clinico-pathological and genetic study.

Non-syndromic pituitary gigantism can result from AIP mutations or the recently identified Xq26.3 microduplication causing X-linked acrogigantism (XLAG). Within Xq26.3, GPR101 is believed to be the causative gene, and the c.924G > C (p.E308D) variant in this orphan G protein-coupled receptor has been suggested to play a role in the pathogenesis of acromegaly.We studied 153 patients (58 females and 95 males) with pituitary gigantism. AIP mutation-negative cases were screened for GPR101 duplication through copy number variation droplet digital PCR and high-density aCGH. The genetic, clinical and histopathological features of XLAG patients were studied in detail. 395 peripheral blood and 193 pituitary tumor DNA samples from acromegaly patients were tested for GPR101 variants.We identified 12 patients (10 females and 2 males; 7.8 %) with XLAG. In one subject, the duplicated region only contained GPR101, but not the other three genes in found to be duplicated in the previously reported patients, defining a new smallest region of overlap of duplications. While females presented with germline mutations, the two male patients harbored the mutation in a mosaic state. Nine patients had pituitary adenomas, while three had hyperplasia. The comparison of the features of XLAG, AIP-positive and GPR101&AIP-negative patients revealed significant differences in sex distribution, age at onset, height, prolactin co-secretion and histological features. The pathological features of XLAG-related adenomas were remarkably similar. These tumors had a sinusoidal and lobular architecture. Sparsely and densely granulated somatotrophs were admixed with lactotrophs; follicle-like structures and calcifications were commonly observed. Patients with sporadic of familial acromegaly did not have an increased prevalence of the c.924G > C (p.E308D) GPR101 variant compared to public databases.In conclusion, XLAG can result from germline or somatic duplication of GPR101. Duplication of GPR101 alone is sufficient for the development of XLAG, implicating it as the causative gene within the Xq26.3 region. The pathological features of XLAG-associated pituitary adenomas are typical and, together with the clinical phenotype, should prompt genetic testing.

AIP mutations in young patients with acromegaly and the Tampico Giant: the Mexican experience.

Although aryl hydrocarbon receptor-interacting protein (AIP) mutations are rare in sporadic acromegaly, their prevalence among young patients is nonnegligible. The objectives of this study were to evaluate the frequency of AIP mutations in a cohort of Mexican patients with acromegaly with disease onset before the age of 30 and to search for molecular abnormalities in the AIP gene in teeth obtained from the "Tampico Giant". Peripheral blood DNA from 71 patients with acromegaly (51 females) with disease onset <30 years was analysed (median age of disease onset of 23 years) and correlated with clinical, biochemical and imaging characteristics. Sequencing was also carried out in DNA extracted from teeth of the Tampico Giant. Five patients (7 %) harboured heterozygous, germline mutations of the AIP gene. In two of them (a 9-year-old girl with gigantism and a young man with symptoms of GH excess since age 14) the c.910C>T (p.Arg304Ter), well-known truncating mutation was identified; in one of these two cases and her identical twin sister, the mutation proved to be a de novo event, since neither of their parents were found to be carriers. In the remaining three patients, new mutations were identified: a frameshift mutation (c.976_977insC, p.Gly326AfsTer), an in-frame deletion (c.872_877del, p.Val291_Leu292del) and a nonsense mutation (c.868A > T, p.Lys290Ter), which are predicted to be pathogenic based on in silico analysis. Patients with AIP mutations tended to have an earlier onset of acromegaly and harboured larger and more invasive tumours. A previously described genetic variant of unknown significance (c.869C > T, p.Ala299Val) was identified in DNA from the Tampico Giant. The prevalence of AIP mutations in young Mexican patients with acromegaly is similar to that of European cohorts. Our results support the need for genetic evaluation of patients with early onset acromegaly.

Somatic GPR101 Duplication Causing X-Linked Acrogigantism (XLAG)-Diagnosis and Management.

CONTEXT: Recent reports have proposed that sporadic or familial germline Xq26.3 microduplications involving the GPR101 gene are associated with early-onset X-linked acrogigantism (XLAG) with a female preponderance. CASE DESCRIPTION: A 4-year-old boy presented with rapid growth over the previous 2 years. He complained of sporadic headaches and had coarse facial features. His height Z-score was +4.89, and weight Z-score was +5.57. Laboratory testing revealed elevated serum prolactin (185 µg/L; normal, <18 µg/L), IGF-1 (745 µg/L; normal, 64-369 µg/L), and fasting GH > 35.0 µg/L. Magnetic resonance imaging demonstrated a homogenous bulky pituitary gland (18 × 15 × 13 mm) without obvious adenoma. A pituitary biopsy showed hyperplastic pituitary tissue with enlarged cords of GH and prolactin cells. Germline PRKAR1A, MEN1, AIP, DICER1, CDKN1B, and somatic GNAS mutations were negative. Medical management was challenging until institution of continuous sc infusion of short-acting octreotide combined with sc pegvisomant and oral cabergoline. The patient remains well controlled with minimal side effects 7 years after presentation. His phenotype suggested XLAG, but his peripheral leukocyte-, saliva-, and buccal cell-derived DNA tested negative for microduplication in Xq26.3 or GPR101. However, DNA isolated from the pituitary tissue and forearm skin showed duplicated dosage of GPR101, suggesting that he is mosaic for this genetic abnormality. CONCLUSIONS: Our patient is the first to be described with somatic microduplication leading to typical XLAG phenotype. This patient demonstrates that a negative test for Xq26.3 microduplication or GPR101 duplication on peripheral blood DNA does not exclude the diagnosis of XLAG because it can result from a mosaic mutation affecting the pituitary.

Evaluation of the Added Value of Diffusion-Weighted Imaging to Conventional Magnetic Resonance Imaging in Pancreatic Neuroendocrine Tumors and Comparison With 68Ga-DOTANOC Positron Emission Tomography/Computed Tomography.

OBJECTIVES: The aims of this study were to investigate the added value of diffusion-weighted imaging (DWI) in pancreatic neuroendocrine tumor (pNET) evaluation and to compare magnetic resonance imaging (MRI) to Ga-DOTANOC positron emission tomography/computed tomography (PET/CT) results. METHODS: Morphological MRI (T2-weighted [T2-w] + contrast-enhanced [CE] T1-w) and DWI (T2-w + DWI) and Ga-DOTANOC PET/CT in 25 patients/30 pNETs were retrospectively evaluated. Per-patient and per-lesion detection rates (pDR and lDR, respectively) were calculated. Apparent diffusion coefficient values were compared among pNET and surrounding and normal pancreas (control group, 18 patients). Apparent diffusion coefficient and standardized uptake value (SUV) values were compared among different grading and staging groups. RESULTS: No statistically significant differences in PET/CT and MRI session detection rates were found (morphological MRI and DW-MRI, 88% pDR and 87% lDR; combined evaluation, 92% pDR and 90% lDR; Ga-DOTANOC PET/CT, 88% pDR and 80% lDR). Consensus reading (morphological/DW-MRI + PET/CT) improved pDR and lDR (100%). Apparent diffusion coefficient mean value was significantly lower compared with surrounding and normal parenchyma (P < 0.01). The apparent diffusion coefficient and SUV values of pNETs among different grading and staging groups were not statistically different. CONCLUSIONS: Conventional MRI, DW-MRI + T2-w sequences, and Ga-DOTANOC PET/CT can be alternative tools in pNET detection. Diffusion-weighted MRI could be valuable in patients with clinical suspicion but negative conventional imaging findings. However, the consensus reading of the 3 techniques seems the best approach.

Factors predicting pasireotide responsiveness in somatotroph pituitary adenomas resistant to first-generation somatostatin analogues: an immunohistochemical study.

AIM: To gather data regarding factors predicting responsiveness to pasireotide in acromegaly. PATIENTS AND METHODS: SSTR2a, SSTR3, SSTR5, AIP, Ki-67 and the adenoma subtype were evaluated in somatotroph adenomas from 39 patients treated post-operatively with somatostatin analogues (SSAs). A standardized SSTR scoring system was applied (scores 0-3). All patients received first-generation SSAs, and 11 resistant patients were subsequently treated with pasireotide LAR. RESULTS: None of the patients with negative or cytoplasmic-only SSTR2a expression (scores 0-1) were responsive to first-generation SSAs, as opposed to 20% (score 2) and 50% of patients with a score of 3 (P=0.04). None of the patients with an SSTR5 score of 0-1 were responsive to pasireotide, as opposed to 5/7 cases with a score of 2 or 3 (P=0.02). SSTR3 expression did not influence first-generation SSAs or pasireotide responsiveness. Tumours with low AIP were resistant to first-generation SSAs (100 vs 60%; P=0.02), while they had similar responsiveness to pasireotide compared to tumours with conserved AIP expression (50 vs 40%; P=0.74). Tumours with low AIP displayed reduced SSTR2 (SSTR2a scores 0-1 44.4 vs 6.7%; P=0.006) while no difference was seen in SSTR5 (SSTR5 scores 0-1 33.3 vs 23.3%; P=0.55). Sparsely granulated adenomas responded better to pasireotide compared to densely granulated ones (80 vs 16.7%; P=0.04). CONCLUSION: The expression of SSTR5 might predict responsiveness to pasireotide in acromegaly. AIP deficient and sparsely granulated adenomas may benefit from pasireotide treatment. These results need to be confirmed in larger series of pasireotide-treated patients.