Risk category system to identify pituitary adenoma patients with AIP mutations

Genetic testing in prolactinomas: a cohort study

BACKGROUND

Prolactinomas represent 46%-66% of pituitary adenomas, but the prevalence of germline mutations is largely unknown. We present here the first study focusing on hereditary predisposition to prolactinoma.

OBJECTIVE

We studied the prevalence of germline mutations in a large cohort of patients with isolated prolactinomas.

MATERIALS AND METHODS

A retrospective study was performed combining genetic and clinical data from patients referred for genetic testing of MEN1, AIP, and CDKN1B between 2003 and 2020. SF3B1 was Sanger sequenced in genetically negative patients.

RESULTS

About 506 patients with a prolactinoma were included: 80 with microprolactinoma (15.9%), 378 with macroprolactinoma (74.7%), 48 unknown; 49/506 in a familial context (9.7%). Among these, 14 (2.8%) had a (likely) pathogenic variant (LPV) in MEN1 or AIP, and none in CDKN1B. All positive patients had developed a macroprolactinoma before age 30. The prevalence of germline mutations in patients with isolated macroprolactinoma under 30 was 4% (11/258) in a sporadic context and 15% (3/20) in a familial context. Prevalence in sporadic cases younger than 18 was 15% in men (5/33) and 7% in women (4/57). No R625H SF3B1 germline mutation was identified in 264 patients with macroprolactinomas.

CONCLUSIONS

We did not identify any LPVs in patients over 30 years of age, either in a familial or in a sporadic context, and in a sporadic context in our series or the literature. Special attention should be paid to young patients and to familial context.

Genetic Testing in Hereditary Pituitary Tumors

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

Low frequency of AIP mutations in patients with young-onset sporadic pituitary macroadenomas

PURPOSE

Mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene cause familial isolated pituitary adenomas (FIPA). AIP mutations have also been found in patients with apparently sporadic pituitary adenomas, particularly in young patients with large adenomas. The aim of this study was to determine the frequency of AIP germline mutations in patients with young-onset sporadic pituitary macroadenomas.

METHODS

The AIP gene was sequenced in 218 Portuguese patients with sporadic pituitary macroadenomas diagnosed before the age of 40 years.

RESULTS

Heterozygous rare sequence variants in AIP were identified in 18 (8.3%) patients. However, only four (1.8%) patients had pathogenic or likely pathogenic variants. These consisted of two already known mutations (p.Arg81* and p.Leu115Trpfs*41) and two novel mutations (p.Glu246*, p.Ser53Thrfs*36). All four patients had GH-secreting adenomas diagnosed between the ages of 14 and 25 years. The frequency of AIP pathogenic or likely pathogenic variants in patients under the age of 30 and 18 years was 3.4% and 5.0%, respectively.

CONCLUSION

The frequency of AIP mutations in this cohort was lower than in other studies. Previous reports may have overestimated the contribution of AIP mutations due to the inclusion of genetic variants of uncertain significance. The identification of novel AIP mutations expands the known spectrum of genetic causes of pituitary adenomas and may help understand the role of AIP mutations in the molecular mechanisms underlying pituitary tumorigenesis.

An update on, and genetics of refractory adenomas of childhood

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

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.

MicroRNA in Acromegaly: Involvement in the Pathogenesis and in the Response to First-Generation Somatostatin Receptor Ligands

Acromegaly is a chronic and systemic disease due to excessive growth hormone and insulin-like growth factor type I caused, in the vast majority of cases, by a GH-secreting pituitary adenoma. About 40% of these tumors have somatic mutations in the stimulatory G protein alpha-subunit 1 gene. The pathogenesis of the remaining tumors, however, is still not fully comprehended. Surgery is the first-line therapy for these tumors, and first-generation somatostatin receptor ligands (fg-SRL) are the most prescribed medications in patients who are not cured by surgery. MicroRNAs are small, non-coding RNAs that control the translation of many mRNAs, and are involved in the post-transcriptional regulation of gene expression. Differentially expressed miRNAs can explain differences in the pathogenesis of acromegaly and tumor resistance. In this review, we focus on the most validated miRNAs, which are mainly involved in acromegaly’s tumorigenesis and fg-SRL resistance, as well as in circulating miRNAs in acromegaly.

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

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

Pituitary microadenoma with hypopituitarism presenting as hyponatremia

The incidence of pituitary adenoma has been increasing these days. Majority of the cases are incidental findings on imaging; and these patients may be asymptomatic without any laboratory abnormalities. However, a non-functional sellar mass can initially present with hypopituitarism. The patient being described is an elderly female who presented with severe hyponatraemia. She has history of recurrent admissions for hyponatraemia in the past. Her biochemical evaluation revealed hypopituitarism and magnetic resonance imaging of brain showed pituitary microadenoma. Hyponatraemia as a presenting feature of hypopituitarism due to pituitary microadenoma is an uncommon scenario.

Apoplexy in sporadic pituitary adenomas: a single referral center experience and AIP mutation analysis

Objective

To analyze the clinical, laboratory, and radiological findings and management of patients with clinical pituitary apoplexy and to screen for aryl hydrocarbon receptor-interacting protein (AIP) mutations.

Methods

The clinical findings were collected from the medical records of consecutive sporadic pituitary adenoma patients with clinical apoplexy. Possible precipitating factors, laboratory data, magnetic resonance imaging (MRI) findings and treatment were also analyzed. Peripheral blood samples were obtained for DNA extraction from leukocytes, and the entire AIP coding region was sequenced.

Results

Thirty-five patients with pituitary adenoma were included, and 23 (67%) had non-functioning pituitary adenomas. Headache was observed in 31 (89%) patients. No clear precipitating factor was identified. Hypopituitarism was observed in 14 (40%) patients. MRI from 20 patients was analyzed, and 10 (50%) maintained a hyperintense signal in MRI performed more than three weeks after pituitary apoplexy (PA). Surgery was performed in ten (28%) patients, and 25 (72%) were treated conservatively with good outcomes. No AIP mutation was found in this cohort.

Conclusion

Patients with stable neuroophthalmological impairments can be treated conservatively if no significant visual loss is present. Our radiological findings suggest that hematoma absorption lasts more than that observed in other parts of the brain. Additionally, our study suggests no benefits of AIP mutation screening in sporadic patients with apoplexy.

Genetics of Acromegaly and Gigantism

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

Novel Insights into Pituitary Tumorigenesis: Genetic and Epigenetic Mechanisms

Substantial advances have been made recently in the pathobiology of pituitary tumors. Similar to many other endocrine tumors, over the last few years we have recognized the role of germline and somatic mutations in a number of syndromic or nonsyndromic conditions with pituitary tumor predisposition. These include the identification of novel germline variants in patients with familial or simplex pituitary tumors and establishment of novel somatic variants identified through next generation sequencing. Advanced techniques have allowed the exploration of epigenetic mechanisms mediated through DNA methylation, histone modifications and noncoding RNAs, such as microRNA, long noncoding RNAs and circular RNAs. These mechanisms can influence tumor formation, growth, and invasion. While genetic and epigenetic mechanisms often disrupt similar pathways, such as cell cycle regulation, in pituitary tumors there is little overlap between genes altered by germline, somatic, and epigenetic mechanisms. The interplay between these complex mechanisms driving tumorigenesis are best studied in the emerging multiomics studies. Here, we summarize insights from the recent developments in the regulation of pituitary tumorigenesis.

Differentiated thyroid carcinoma in sporadic and familial presentations of acromegaly: A case series

BACKGROUND

In acromegaly, chronic growth hormone (GH) and insulin-like growth factor-1 (IGF-1) exacerbate comorbidities in multiple organs. Differentiated thyroid carcinoma (DTC) has been reported as being a comorbid condition in acromegaly. Acromegaly is usuallysporadic, but 5% of cases may be genetic. The most frequent inheritable form of acromegaly is related to germline mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene. Epidemiological data on the relationship between active acromegaly, its familial forms and DTC are sparse. We present the investigation of a FIPA family (familial isolated pituitary adenoma) with homogeneous acromegaly and 6 sporadic acromegaly patients with DTC.

PATIENTS AND METHODS

A study of 59 acromegaly patients assessed thyroid nodules on ultrasound and fine-needle aspiration biopsy following the ATA 2015 criteria. We diagnosed 7 differentiated thyroid carcinomas. Resected thyroid carcinoma tissues were stained using an anti-AIP antibody. Analysis of germline and tumor-derived DNA for variants in the AIP and MEN1 genes were performed in the FIPA kindred.

RESULTS

We describe one FIPA patient and 6 sporadic acromegaly cases with DTC. The FIPA family (AIP mutation negative) consisted of two sisters, one of whom had a DTC with intermediate risk and incomplete structural response to therapy. In our study, DTC in sporadic acromegaly had a low recurrence rate (6/6), and excellent response to therapy (6/6). Immunohistochemistry for AIP showed similar or increased staining intensity in DTC versus normal thyroid tissue.

CONCLUSION

In our cohort of sporadic and familial forms of acromegaly with DTC, AIP did not appear to influence thyroid cancer progression.

Pituitary Metastatic Composite Tumors: A Case Report with Next-Generation Sequencing and Review of the Literature

Background

While pituitary tumors are well understood, little research has been done on metastasis from primary tumors into pituitary adenomas, also known as composite tumors. Because only 34 cases of composite tumors have been reported to date, we hope to better characterize these tumors by reviewing cases reported in the literature and reviewed our own documented case, which includes next-generation sequencing. Case Presentation. A 74-year-old man presented to the emergency department with left vision loss for 3 months. He had a history of colon cancer treated with colectomy and clear cell renal carcinoma treated with left nephrectomy. A preoperative MRI demonstrated growth of a peripherally enhancing, centrally necrotic mass with sellar expansion measuring 5.7 × 3.1 × 3.0 cm. Given these findings, an endoscopic endonasal transsphenoidal resection was performed. Histological assessment revealed a composite tumor: one neoplasm was a nonfunctioning pituitary adenoma, and another neoplasm was a clear cell carcinoma. Next-generation sequencing demonstrated that the tumors shared mutations in VHL and Notch2. The patient died 2 months later from systemic metastatic cancer.

Conclusion

From our literature review, most metastatic lesions in these composite tumors originated from neoplasms of the lung and kidney. Approximately 63% patients presented with ophthalmoplegia as the initial symptom while 23% displayed hormonal abnormalities. Postoperative mortality had a median of 3.5 months. In our patient, the presence of VHL and Notch2 mutations in both tumors highlights the possibility of using next-generation sequencing to help identify therapeutic targets even in complex composite neoplasms.

The tumour microenvironment of pituitary neuroendocrine tumours

The tumour microenvironment (TME) includes a variety of non-neoplastic cells and non-cellular elements such as cytokines, growth factors and enzymes surrounding tumour cells. The TME emerged as a key modulator of tumour initiation, progression and invasion, with extensive data available in many cancers, but little is known in pituitary tumours. However, the understanding of the TME of pituitary tumours has advanced thanks to active research in this field over the last decade. Different immune and stromal cell subpopulations, and several cytokines, growth factors and matrix remodelling enzymes, have been characterised in pituitary tumours. Studying the TME in pituitary tumours may lead to a better understanding of tumourigenic mechanisms, identification of biomarkers useful to predict aggressive disease, and development of novel therapies. This review summarises the current knowledge on the different TME cellular/non-cellular elements in pituitary tumours and provides an overview of their role in tumourigenesis, biological behaviour and clinical outcomes.

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.

Aggressive pituitary tumors in the young and elderly

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

Potential markers of disease behavior in acromegaly and gigantism

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

Acromegaly in the setting of Tatton-Brown-Rahman Syndrome

PURPOSE

Tatton-Brown-Rahman syndrome (TBRS) is a newly defined genetic entity characterized by overgrowth and intellectual disability, resulting from germline mutations in the gene encoding DNA methyltransferase 3 alpha (DNMT3A). Affected individuals with benign and malignant tumors have been reported; to our knowledge pituitary adenomas (and other tumors identified in our patient) have not yet been described in this syndrome.

CASE

We report the case of a 34-year-old woman with TBRS who developed a GH-secreting pituitary macroadenoma and other benign tumors and cystic lesions involving diverse organ systems. Whole-exome sequencing revealed a heterozygous, likely pathogenic variant (c.700_709 del10, p. Gly234ArgfsX79) in exon7 of DNMT3A, and a heterozygous variant of uncertain significance (c.25 C>T, p.Arg9Trp) in exon 1 of the gene encoding aryl hydrocarbon receptor-interacting protein (AIP). The patient failed somatostatin analog treatment, and underwent surgery. The tumor retained AIP expression, and analysis of tumor DNA indicated the presence of both AIP alleles, consistent with no loss of heterozygosity. These findings suggest that the AIP variant was not the primary driver of pituitary adenoma development.

CONCLUSION

Our case suggests that TBRS might be associated with pituitary adenoma and a broader spectrum of tumors than previously thought, making long-term follow up of these patients crucial to identify tumors early, and to elucidate the clinical spectrum of the disorder for optimization of management.

The Genetics of Pituitary Adenomas

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

Genetics of Pituitary Tumours

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

[Interdisciplinary Management of Sellar Masses]

Interdisciplinary Management of Sellar Masses Abstract. Sellar masses may present with an impairment of pituitary function (hypopituitarism), hormone hypersecretion (prolactinoma, acromegaly, glucocorticoid excess) or neurological symptoms (visual impairment, headache). An increasing number of them is discovered as an incidentaloma. Among the various entities, benign pituitary adenomas and cystic lesions are most frequently encountered. The work-up includes a laboratory evaluation for hormone hyper- or hyposecretion and an MRI of the pituitary gland. If the optic chiasm is compromised, a visual field examination is mandatory. Except for prolactinomas, symptomatic sellar masses are usually resected via an endoscopic transsphenoidal approach. If a total resection is not feasible because of the invasion of surrounding structures, debulking to relieve pressure from the optic chiasm is the primary goal and radiotherapy may be considered. Residual hormone excess can be treated medically. In the early postoperative period special attention to the development and treatment of disordered body water homeostasis and hypopituitarism is crucial. Interdisciplinary work-up and decision making are of utmost importance and will offer the best management.

AIP and MEN1 mutations and AIP immunohistochemistry in pituitary adenomas in a tertiary referral center

BACKGROUND

Pituitary adenomas have a high disease burden due to tumor growth/invasion and disordered hormonal secretion. Germline mutations in genes such as MEN1 and AIP are associated with early onset of aggressive pituitary adenomas that can be resistant to medical therapy.

AIMS

We performed a retrospective screening study using published risk criteria to assess the frequency of AIP and MEN1 mutations in pituitary adenoma patients in a tertiary referral center.

METHODS

Pituitary adenoma patients with pediatric/adolescent onset, macroadenomas occurring ≤30 years of age, familial isolated pituitary adenoma (FIPA) kindreds and acromegaly or prolactinoma cases that were uncontrolled by medical therapy were studied genetically. We also assessed whether immunohistochemical staining for AIP (AIP-IHC) in somatotropinomas was associated with somatostatin analogs (SSA) response.

RESULTS

Fifty-five patients met the study criteria and underwent genetic screening for AIP/MEN1 mutations. No mutations were identified and large deletions/duplications were ruled out using MLPA. In a cohort of sporadic somatotropinomas, low AIP-IHC tumors were significantly larger (P = 0.002) and were more frequently sparsely granulated (P = 0.046) than high AIP-IHC tumors. No significant relationship between AIP-IHC and SSA responses was seen.

CONCLUSIONS

Germline mutations in AIP/MEN1 in pituitary adenoma patients are rare and the use of general risk criteria did not identify cases in a large tertiary-referral setting. In acromegaly, low AIP-IHC was related to larger tumor size and more frequent sparsely granulated subtype but no relationship with SSA responsiveness was seen. The genetics of pituitary adenomas remains largely unexplained and AIP screening criteria could be significantly refined to focus on large, aggressive tumors in young patients.

Advances and controversies in the classification and grading of pituitary tumors

BACKGROUND

Pituitary tumors are common lesions, and they represent the second most frequent primary brain tumor. Their classification has undergone several changes over time. The World Health Organization conducts periodic expert review/consensus meetings and publishes the results as recommendations for changes in classification, based on advances in molecular and genetic advances. This paper summarizes the results of the 2017 WHO Classification, which recommends several important changes.

PURPOSE

This paper provides a review of the major changes and issues leading to an understanding of the basis for a new pituitary tumor classification. They include the rejection and modification of prior conceptual and pathological characteristics of these neoplasms. There is also considerable concern related to invasive and recurrent pituitary tumors which follow a less benign course than the typical pituitary adenoma.

METHODS

A review of the outcome data for the previously designated "atypical" pituitary tumor category revealed that the former criteria were not adequate to support their ability to predict with accuracy the clinical course of a given tumor. A similar review was accomplished regarding the role of the p53 tumor suppressor mutation. Again, there was no reliable contribution of p53 status to tumor aggressiveness. Other changes have occurred regarding the cytogenetic lineage of the various subtypes of pituitary adenoma. The transcription factors Pit-1, SF-1, and TPit play a major role in determining tumor subtypes and have become part of the classification criteria.

RESULTS

These advances now help provide the background for more reliable and consistent classification of pituitary adenomas. Further definition of aggressive characteristics such as cavernous sinus and dural invasion remain to be considered in the quest to make more accurate prognostic projections based on histopathological analysis.

CONCLUSIONS

The 2017 WHO Classification of Pituitary Tumors provides a more solid basis for accurate and reliable prognostic assessment of these lesions. Further progress undoubtedly will be made as the recommendations of this update are incorporated in to routine use.

Three Novel MEN1 Variants in AIP-Negative Familial Isolated Pituitary Adenoma Patients

OBJECTIVES

Pituitary adenomas (PAs) may rarely occur in well-defined hereditary conditions, like multiple endocrine neoplasia type 1 (MEN1) syndrome and familial isolated pituitary adenoma (FIPA) associated with germline mutations in MEN1 and AIP, respectively. This study aimed to assess MEN1 genetic abnormalities in AIP mutation-negative FIPA patients, not associated with MEN1 components.

METHODS

Among 20 patients evaluated in 13 FIPA families, 12 were previously reported as AIP mutation-negative. In this study, 6 new families with 8 patients were recruited. All patients were subjected to multiplex ligation-dependent probe amplification to detect copy number variations in AIP and MEN1, and AIP sequencing was performed in additional patients. AIP mutation-negative patients were subjected to MEN1 sequencing.

RESULTS

Our cohort revealed only 3 novel heterozygous MEN1 variants including c.1846T>A p.(*616Argext*21), rs778272737:T>C, and rs972128957:C>T in 2 families, with patients diagnosed with Cushing disease, nonfunction al adenoma, and acromegaly, respectively. Among them, c.1846T>A p. (*616Argext*21) is a stop codon read-through, whereas the others are 3'UTR variations. MEN1 variation frequency was detected as 15%.

CONCLUSIONS

MEN1 alterations can be of significance in FIPA patients and screening could be offered to AIP mutation-negative patients without MEN1 features. Further studies are needed to clarify the role of MEN1 in FIPA patients.

A. Phosphodiesterases and cAMP Pathway in Pituitary Diseases

Human phosphodiesterases (PDEs) comprise a complex superfamily of enzymes derived from 24 genes separated into 11 PDE gene families (PDEs 1-11), expressed in different tissues and cells, including heart and brain. The isoforms PDE4, PDE7, and PDE8 are specific for the second messenger cAMP, which is responsible for mediating diverse physiological actions involving different hormones and neurotransmitters. The cAMP pathway plays an important role in the development and function of endocrine tissues while phosphodiesterases are responsible for ensuring the appropriate intensity of the actions of this pathway by hydrolyzing cAMP to its inactive form 5'-AMP. PDE1, PDE2, PDE4, and PDE11A are highly expressed in the pituitary, and overexpression of some PDE4 isoforms have been demonstrated in different pituitary adenoma subtypes. This observed over-expression in pituitary adenomas, although of unknown etiology, has been considered a compensatory response to tumorigenesis. PDE4A4/5 has a unique interaction with the co-chaperone aryl hydrocarbon receptor-interacting protein (AIP), a protein implicated in somatotroph tumorigenesis via germline loss-of-function mutations. Based on the association of low PDE4A4 expression with germline AIP-mutation-positive samples, the available data suggest that lack of AIP hinders the upregulation of PDE4A4 protein seen in sporadic somatotrophinomas. This unique disturbance of the cAMP-PDE pathway observed in the majority of AIP-mutation positive adenomas could contribute to their well-described poor response to somatostatin analogs and may support a role in tumorigenesis.

Clinical Relevance of Genetic Analysis in Patients With Pituitary Adenomas: A Systematic Review

Pituitary adenomas (PA) are amongst the most prevalent intracranial tumors, causing complications by hormonal overproduction or deficiency and tumor mass effects, with 95% of cases occurring sporadically. Associated germline mutations (AIP, MEN1, CDKN1B, PRKAR1A, SDHx) and Xq26.3 microduplications are increasingly identified, but the clinical consequences in sporadic PA remain unclear. This systematic review evaluates predictors of a genetic cause of sporadic PA and the consequences for treatment outcome. We undertook a sensitive MEDLINE/Pubmed, EMBASE, and Web of Science search with critical appraisal of identified studies. Thirty-seven studies on predictors of mutations and 10 studies on the influence on treatment outcome were included. AIP and MEN1 mutations were associated with young age of PA diagnosis. AIP mutations were also associated with gigantism and macroadenomas at time of diagnosis. Xq26.3 microduplications were associated with PA below the age of five. AIP and MEN1 mutation analysis is therefore recommended in young patients (≤30 years). AIP mutation analysis is specifically recommended for patients with PA induced gigantism and macroadenoma. Screening for Xq26.3 microduplications is advisable in children below the age of five with increased growth velocity due to PA. There is no evidence supporting mutation analysis of other genes in sporadic PA. MEN1 mutation related prolactinoma respond well to dopamine agonists while AIP mutation associated somatotroph and lactotroph adenoma are frequently resistant to medical treatment. In patients harboring an Xq26.3 microduplication treatment is challenging, although outcome is not different from other patients with PA induced gigantism. Effective use of genetic analysis may lead to early disease identification, while knowledge of the impact of germline mutations on susceptibility to various treatment modalities helps to determine therapeutic strategies, possibly lowering disease morbidity.