Parasympathetic paragangliomas are part of the Von Hippel-Lindau syndrome

Expression of Hemangioblast Proteins in von Hippel-Lindau Disease Related Tumors

Von Hippel-Lindau (VHL) disease is a hereditary tumor syndrome that targets a highly selective subset of organs causing specific types of tumors. The biological basis for this principle of organ selectivity and tumor specificity is not well understood. VHL-associated hemangioblastomas share similar molecular and morphological features with embryonic blood and vascular precursor cells. Therefore, we suggest that VHL hemangioblastomas are derived from developmentally arrested hemangioblastic lineage keeping their potential of further differentiation. Due to these common features, it is of major interest to investigate whether VHL-associated tumors other than hemangioblastoma also share these pathways and molecular features. The expression of hemangioblast proteins has not yet been assessed in other VHL-related tumors. To gain a better understanding of VHL tumorigenesis, the expression of hemangioblastic proteins in different VHL-associated tumors was investigated. The expression of embryonic hemangioblast proteins Brachyury and TAL1 (T-cell acute lymphocytic leukemia protein 1) was assessed by immunohistochemistry staining on 75 VHL-related tumors of 51 patients: 47 hemangioblastomas, 13 clear cell renal cell carcinomas, 8 pheochromocytomas, 5 pancreatic neuroendocrine tumors, and 2 extra-adrenal paragangliomas. Brachyury and TAL1 expression was, respectively, observed in 26% and 93% of cerebellar hemangioblastomas, 55% and 95% of spinal hemangioblastomas, 23% and 92% of clear cell renal cell carcinomas, 38% and 88% of pheochromocytomas, 60% and 100% of pancreatic neuroendocrine tumors, and 50% and 100% of paragangliomas. We concluded that the expression of hemangioblast proteins in different VHL-associated tumors indicates a common embryological origin of these lesions. This may also explain the specific topographic distribution of VHL-associated tumors.

Retroperitoneal paraganglioma with loss of heterozygosity of the von Hippel-Lindau gene: a case report and review of the literature

Von Hippel-Lindau (VHL) disease is an autosomal dominant disease related to germline mutations in VHL. In VHL disease, pheochromocytoma develops in 10%-20% of patients because of germline mutations and loss of heterozygosity of VHL. However, the rate of paraganglioma associated with VHL is low compared with that of pheochromocytoma, and the reason is unknown. In this study, we performed germline and somatic mutation analyses of retroperitoneal paraganglioma that developed in a patient with clinically diagnosed VHL disease and investigated the tumorigenic mechanism of paraganglioma. The patient was a 25-year-old woman who was considered to have VHL disease on the basis of her family history. She was referred to our clinic to investigate a tumor at the bifurcation of the common iliac artery. The tumor was diagnosed as retroperitoneal paraganglioma by clinical evaluations. A left renal cell carcinoma was also suspected. Polymerase chain reaction direct sequencing analysis and polymorphic microsatellite analysis within the VHL locus suggested that loss of heterozygosity of VHL was associated with paraganglioma and renal cell carcinoma. Multiplex ligation-dependent probe amplification analysis showed a loss of the copy number of VHL exons in paraganglioma. These results suggest that VHL disease contributes to the development of paraganglioma. A literature review showed no reported common missense variants involved in the progression of paraganglioma. The loss of heterozygosity of VHL can be a tumorigenic mechanism of retroperitoneal paraganglioma in VHL disease. However, the low rate of paraganglioma compared with pheochromocytoma is not explained by their genetic background alone.

Suprasellar paraganglioma in a clinical setting of von Hippel-Lindau syndrome

A man in his 20s presented to the neurosurgery department 2 years ago with headache and blurred vision. He was diagnosed to have a suprasellar mass on neuroimaging. Best-corrected visual acuity in the right eye was 6/36 and that in the left eye was 6/60. Automated visual fields showed a temporal hemianopia in the right eye and an advanced field defect in the left eye. His hormonal profile was normal, and he underwent partial excision of suprasellar tumour, which was a histopathologically proven paraganglioma (PGL). Subsequently, the patient underwent radiotherapy and his vision and visual fields showed improvement. Follow-up examination 3 years later showed a left retinal capillary hemangioblastoma (RCH), which was treated with green laser photocoagulation, resulting in complete sclerosis. This case is unique because of the extremely rare coexistence of a sellar PGL and RCH, which to our knowledge has not been reported so far.

Genetics of Pheochromocytomas and Paragangliomas Determine the Therapeutical Approach

Pheochromocytomas and paragangliomas are the most heritable endocrine tumors. In addition to the inherited mutation other driver mutations have also been identified in tumor tissues. All these genetic alterations are clustered in distinct groups which determine the pathomechanisms. Most of these tumors are benign and their surgical removal will resolve patient management. However, 5–15% of them are malignant and therapeutical possibilities for them are limited. This review provides a brief insight about the tumorigenesis associated with pheochromocytomas/paragangliomas in order to present them as potential therapeutical targets.

Pheochromocytoma and paraganglioma: germline genetics and hereditary syndromes

Pheochromocytomas (PCCs) and paragangliomas (PGLs) are neuroendocrine tumors arising from the adrenal medulla and extra-adrenal ganglia, respectively. Approximately 15-25% of PCC/PGL can become metastatic. Up to 30-40% of patients with PCC/PGL have a germline pathogenic variant in a known susceptibility gene for PCC/PGL; therefore, all patients with PCC/PGL should undergo clinical genetic testing. Most of the susceptibility genes are associated with variable penetrance for PCC/PGL and are associated with different syndromes, which include susceptibility for other tumors and conditions. The objective of this review is to provide an overview of the germline susceptibility genes for PCC/PGL, the associated clinical syndromes, and recommended surveillance.

Pathogenicity of VHL variants in families with non-syndromic von Hippel-Lindau phenotypes: An integrated evaluation of germline and somatic genomic results

Von Hippel-Lindau (VHL) syndrome is a hereditary tumor syndrome associated with germline loss-of-function pathogenic variants (PVs) in the VHL gene. VHL is classically associated with a high penetrance for many different tumor types. The same tumors may be sporadic in the setting of somatic VHL PVs. With more large-scale genome sequencing, variants with low penetrance or variable expressivity are identified. This has introduced challenges in patient management and the clinical interpretation of germline VHL variants identified in non-classic families. Herein, we report individuals from 3 non-classic families with VHL variants who presented with unexpected or non-syndromic phenotypes, but often with a VHL component tumor. In family 1, two siblings, age 61, with pathogenic VHL p.Leu188Val presented with clear cell renal cell carcinoma and lobular breast cancer. In family 2, the proband, age 82, was found to have pathogenic germline VHL p.Tyr98His on testing for metastatic bladder cancer. In family 3, four members carried germline VHL p.Pro81Ser (variant of uncertain significance), after the proband, age 40, presented with cerebellar hemangioblastoma. None of the individuals in the above three families met clinical criteria of classic VHL, suggesting germline VHL p.Leu188Val, p.Y98H, and p.Tyr98His may be low penetrant variants. Large studies are needed to evaluate penetrance and possible effect of genetic and non-genetic modifiers. Somatic sequencing performed on their respective tumors could help discern the etiology of the component tumors, highlighting the role of somatic evaluation in these cases. Paired examination of somatic and germline findings provided a more complete landscape of genome alterations in cancer development.

Abdominal paraaortic paraganglioma: Management of intraoperative hemodynamic emergencies during elective resection procedures (A case presentation)

Paragangliomas are extremely rare neuroendocrine tumors. We report a case of a 44-year-old man with hypertension who presented a tumoral mass located retroperitoneally at the aortic bifurcation which included both the common iliac arteries and the posterior left iliac vein, who experienced an unpredictable intraoperative cardiac arrest with electromechanical dissociation at 5 min after laparotomy. After successful resuscitation and hemodynamic stability, the lesion was fully excised. In the course of tumor manipulation, the patient developed a major hypertensive crisis with peak systolic blood pressure over 280 mmHg. Pathologic examination revealed the presence of diffuse proliferation of large and medium-sized mature adipocytes consistent with paraganglioma diagnosis. The patient was discharged at home on the seventh postoperative day. He did not present evidence of recurrence at the one-year follow-up. In conclusion, paragangliomas can require particular management due to their location but also due to their capacity to discharge substances which might induce life-threatening intraoperative complications.

Von Hippel-Lindau Disease: Current Challenges and Future Prospects

Understanding of molecular mechanisms of tumor growth has an increasing impact on the development of diagnostics and targeted therapy of human neoplasia. In this review, we summarize the current knowledge on molecular mechanisms and their clinical implications in von Hippel-Lindau (VHL) disease. This autosomal dominant tumor syndrome usually manifests in young adulthood and predisposes affected patients to the development of benign and malignant tumors of different organ systems mainly including the nervous system and internal organs. A consequent screening and timely preventive treatment of lesions are crucial for patients affected by VHL disease. Surgical indications and treatment have been evaluated and optimized over many years. In the last decade, pharmacological therapies have been evolving, but are largely still at an experimental stage. Effective pharmacological therapy as well as detection of biomarkers is based on the understanding of the molecular basis of disease. The molecular basis of von Hippel-Lindau disease is the loss of function of the VHL protein and subsequent accumulation of hypoxia-inducible factor with downstream effects on cellular metabolism and differentiation. Organs affected by VHL disease may develop frank tumors. More characteristically, however, they reveal multiple separate microscopic foci of neoplastic cell proliferation. The exact mechanisms of tumorigenesis in VHL disease are, however, still not entirely understood and knowledge on biomarkers and targeted therapy is scarce.

Metabolic Drivers in Hereditary Cancer Syndromes

Cancer is a multifaceted disease in which inherited genetic variants can be important drivers of tumorigenesis. The discovery that germline mutations of metabolic genes predispose to familial forms of cancer caused a shift in our understanding of how metabolism contributes to tumorigenesis, providing evidence that metabolic alterations can be oncogenic. In this review, we focus on mitochondrial enzymes whose mutations predispose to familial cancer, and we fully appraise their involvement in cancer formation and progression. Elucidating the molecular mechanisms that orchestrate transformation in these diverse tumors may answer key biological questions about tumor formation and evolution, leading to the identification of new therapeutic targets of intervention.

Von Hippel-Lindau "Black Forest" mutation inherited in a large Chinese family

Background

The Von Hippel-Lindau (VHL) p.Tyr98His (Y98H) mutation is designated as the "Black Forest" founder mutation and has been previously reported in Western countries. This study reports the first recorded Chinese VHL family with the "Black Forest" mutation in Asia.

Methods

Paired whole-exome sequencing (WES), Sanger sequencing and immunohistochemistry (IHC) were performed on samples from a large Chinese family to confirm the causative mutation and mutation carriers in the family. Clinical manifestations of the family were summarized and compared with those reported from other patients with the VHL Y98H mutation.

Results

The Chinese pheochromocytoma (PCC) family was identified as a VHL type 2 family with a Y98H mutation. There were 4 VHL patients and 11 currently healthy individuals with the mutation. Copy number analysis and SDHB IHC were performed to exclude interference from other pathogenic genes of PCC or paraganglioma (PGL).

Conclusions

We report the first recorded instance of a Chinese VHL type 2 family with the "Black Forest" mutation by using WES and Sanger sequencing, which widens the currently recorded presence of the "Black Forest" mutation to China and potentially elsewhere in Asia and indicates that the "Black Forest" mutation does not uniquely evolve in occidental countries. A personalized surveillance approach, which may be more appropriate for affected families, has been recommended to improve quality of life.

Pheochromocytoma/Paraganglioma: Is This a Genetic Disorder?

Pheochromocytomas and paragangliomas (PCC/PGL) are neuroendocrine tumors of the adrenal medulla and extra-adrenal ganglia which often over-secrete catecholamines leading to cardiovascular morbidity and even mortality. These unique tumors have the highest heritability of all solid tumor types with up to 35-40% of patients with PCC/PGL having a germline predisposition. PURPOSE OF REVIEW: To review the germline susceptibility genes and clinical syndromes associated with PCC/PGL. RECENT FINDINGS: There are over 12 PCC/PGL susceptibility genes identified in a wide range of pathways. Each gene is associated with a clinical syndrome with varying penetrance for both primary and metastatic PCC/PGL and often includes increased risk for additional tumors besides PCC/PGL. Patients with sporadic or hereditary PCC/PGL should be monitored for life given the risk of multiple primary tumors, recurrence, and metastatic disease. All patients with PCC/PGL should be referred for consideration for clinical genetic testing given the high heritability of disease.

Molecular Alterations in Dog Pheochromocytomas and Paragangliomas

8658860258318000Recently, genetic alterations in the genes encoding succinate dehydrogenase subunit B and D (SDHB and SDHD) were identified in pet dogs that presented with spontaneously arising pheochromocytomas (PCC) and paragangliomas (PGL; together PPGL), suggesting dogs might be an interesting comparative model for the study of human PPGL. To study whether canine PPGL resembled human PPGL, we investigated a series of 50 canine PPGLs by immunohistochemistry to determine the expression of synaptophysin (SYP), tyrosine hydroxylase (TH) and succinate dehydrogenase subunit A (SDHA) and B (SDHB). In parallel, 25 canine PPGLs were screened for mutations in SDHB and SDHD by Sanger sequencing. To detect large chromosomal alterations, single nucleotide polymorphism (SNP) arrays were performed for 11 PPGLs, including cases for which fresh frozen tissue was available. The immunohistochemical markers stained positive in the majority of canine PPGLs. Genetic screening of the canine tumors revealed the previously described variants in four cases; SDHB p.Arg38Gln (n = 1) and SDHD p.Lys122Arg (n = 3). Furthermore, the SNP arrays revealed large chromosomal alterations of which the loss of chromosome 5, partly homologous to human chromosome 1p and chromosome 11, was the most frequent finding (100% of the six cases with chromosomal alterations). In conclusion, canine and human PPGLs show similar genomic alterations, suggestive of common interspecies PPGL-related pathways.

Role of VHL, HIF1A and SDH on the expression of miR-210: Implications for tumoral pseudo-hypoxic fate

The hypoxia-inducible factor 1α (HIF-1α) and its microRNA target, miR-210, are candidate tumor-drivers of metabolic reprogramming in cancer. Neuroendocrine neoplasms such as paragangliomas (PGLs) are particularly appealing for understanding the cancer metabolic adjustments because of their associations with deregulations of metabolic enzymes, such as succinate dehydrogenase (SDH), and the von Hippel Lindau (VHL) gene involved in HIF-1α stabilization. However, the role of miR-210 in the pathogenesis of SDH-related tumors remains an unmet challenge. Herein is described an in vivo genetic analysis of the role of VHL, HIF1A and SDH on miR-210 by using knockout murine models, siRNA gene silencing, and analyses of human tumors. HIF-1α knockout abolished hypoxia-induced miR-210 expression in vivo but did not alter its constitutive expression in paraganglia. Normoxic miR-210 levels substantially increased by complete, but not partial, VHL silencing in paraganglia of knockout VHL-mice and by over-expression of p76del-mutated pVHL. Similarly, VHL-mutated PGLs, not those with decreased VHL-gene/mRNA dosage, over-expressed miR-210 and accumulate HIF-1α in most tumor cells. Ablation of SDH activity in SDHD-null cell lines or reduction of the SDHD or SDHB protein levels elicited by siRNA-induced gene silencing did not induce miR-210 whereas the presence of SDH mutations in PGLs and tumor-derived cell lines was associated with mild increase of miR-210 and the presence of a heterogeneous, HIF-1α-positive and HIF-1α-negative, tumor cell population. Thus, activation of HIF-1α is likely an early event in VHL-defective PGLs directly linked to VHL mutations, but it is a late event favored but not directly triggered by SDHx mutations. This combined analysis provides insights into the mechanisms of HIF-1α/miR-210 regulation in normal and tumor tissues potentially useful for understanding the pathogenesis of cancer and other diseases sharing similar underpinnings.

Von Hippel-Lindau disease: a single gene, several hereditary tumors

The Von Hippel-Lindau (VHL) disease is an autosomal dominant disorder characterized by the predisposition for multiple tumors caused by germline mutations in the tumor suppressor gene VHL. This disease is associated with a high morbidity and mortality and presents a variable expression, with different phenotypes from family to family, affecting different organs during the lifetime. The main manifestations of VHL are hemangioblastomas of the central nervous system and retina, renal carcinomas and cysts, bilateral pheochromocytomas, cystic and solid tumors of the pancreas, cystadenomas of the epididymis, and endolymphatic sac tumors. The discovery of any of the syndrome components should raise suspicion of this disease and other stigmas must then be investigated. Due to the complexities associated with management of the various VHL manifestation, the diagnosis and the follow-up of this syndrome is a challenge in the clinical practice and a multidisciplinary approach is needed. The particular relevance to endocrinologists is the detection of pheochromocytomas in 35% and islet cell tumors in 17% of VHL patients, which can be associated with hypertension, hypoglycemia, cardiac arrhythmias, and carcinoid syndrome. The purpose of this review is to define the Von Hippel-Lindau syndrome addressing its clinical aspects and classification, the importance of genetic counseling and to propose a protocol for clinical follow-up.

PRECISION MEDICINE: AN UPDATE ON GENOTYPE/BIOCHEMICAL PHENOTYPE RELATIONSHIPS IN PHEOCHROMOCYTOMA/PARAGANGLIOMA PATIENTS

OBJECTIVE

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors known to produce and secrete high levels of circulating catecholamines and their metabolites. The biochemical characteristics of these tumors can be used to divide them into three major phenotypes. The adrenergic, noradrenergic and dopaminergic phenotypes are defined by predominant elevations in epinephrine and metanephrine, norepinephrine and normetanephrine, and dopamine and 3-methoxytyramine, respectively. There are over 15 well-identified tumor-susceptibility genes responsible for approximately 40% of the cases. The objective of this review article is to outline specific genotype/biochemical phenotype relationships.

METHODS

Literature review.

RESULTS

None.

CONCLUSION

Biochemical phenotype of PPGL is determined by the underlying genetic mutation and the associated molecular pathway. Identification of genotype/biochemical relationships is valuable in prioritizing testing for specific genes, making treatment decisions and monitoring disease progression.

ABBREVIATIONS

3-MT = 3-methoxytyramine; EPAS1 = endothelial pas domain protein 1; FH = fumarate hydratase; HIF2A = hypoxia inducible factor type 2A; MEN2 = multiple endocrine neoplasia type 2; NF1 = neurofibromatosis type 1; PNMT = phenylethanolamine N-methyltransferase; PPGL = pheochromocytoma and paraganglioma; RET = rearranged during transfection; SDH = succinate dehydrogenase; SDHAF2 = succinate dehydrogenase complex assembly factor 2; TCA = tricarboxylic acid; TH = tyrosine hydroxylase; TMEM127 = transmembrane protein 127; VHL = von Hippel-Lindau.

Diagnosis and Management of Hereditary Phaeochromocytoma and Paraganglioma

About 30% of phaeochromocytomas or paragangliomas are genetic. Whilst some individuals will have clinical features or a family history of inherited cancer syndrome such as neurofibromatosis type 1 (NF1) or multiple endocrine neoplasia 2 (MEN2), the majority will present as an isolated case. To date, 14 genes have been described in which pathogenic mutations have been demonstrated to cause paraganglioma or phaeochromocytoma . Many cases with a pathogenic mutation may be at risk of developing further tumours. Therefore, identification of genetic cases is important in the long-term management of these individuals, ensuring that they are entered into a surveillance programme. Mutation testing also facilitates cascade testing within the family, allowing identification of other at-risk individuals. Many algorithms have been described to facilitate cost-effective genetic testing sequentially of these genes, with phenotypically driven pathways. New genetic technologies including next-generation sequencing and whole-exome sequencing will allow much quicker, cheaper and extensive testing of individuals in whom a genetic aetiology is suspected.

Endocrine manifestations of von Hippel-Lindau disease

von Hippel-Lindau (VHL) disease is an autosomal dominant disorder caused by heterozygous mutations in the VHL tumor suppressor gene that is characterized by the occurrence of multiple endocrine and nonendocrine lesions. This review focuses on the endocrine manifestations of VHL disease. Pancreatic neuroendocrine proliferations (ductuloinsular complexes, islet dysplasia, endocrine microadenoma, and neuroendocrine tumors), pheochromocytomas, and extra-adrenal paragangliomas are important endocrine manifestations of VHL disease. They frequently display characteristic clinical, biochemical, and histopathologic features that, although not pathognomonic, can be helpful in suggesting VHL disease as the underlying etiology and distinguishing these tumors from sporadic cases. Recent improvements in treatment and outcomes of renal cell carcinomas have allowed pancreatic neuroendocrine tumors to emerge as a significant source of metastatic disease, making the accurate recognition and classification of these neoplasms by the pathologist of utmost importance to determine prognosis, treatment, and follow-up strategies for affected patients.

Paragangliomas/Pheochromocytomas: clinically oriented genetic testing

Paragangliomas are rare neuroendocrine tumors that arise in the sympathetic or parasympathetic nervous system. Sympathetic paragangliomas are mainly found in the adrenal medulla (designated pheochromocytomas) but may also have a thoracic, abdominal, or pelvic localization. Parasympathetic paragangliomas are generally located at the head or neck. Knowledge concerning the familial forms of paragangliomas has greatly improved in recent years. Additionally to the genes involved in the classical syndromic forms: VHL gene (von Hippel-Lindau), RET gene (Multiple Endocrine Neoplasia type 2), and NF1 gene (Neurofibromatosis type 1), 10 novel genes have so far been implicated in the occurrence of paragangliomas/pheochromocytomas: SDHA, SDHB, SDHC, SDHD, SDHAF2, TMEM127, MAX, EGLN1, HIF2A, and KIF1B. It is currently accepted that about 35% of the paragangliomas cases are due to germline mutations in one of these genes. Furthermore, somatic mutations of RET, VHL, NF1, MAX, HIF2A, and H-RAS can also be detected. The identification of the mutation responsible for the paraganglioma/pheochromocytoma phenotype in a patient may be crucial in determining the treatment and allowing specific follow-up guidelines, ultimately leading to a better prognosis. Herein, we summarize the most relevant aspects regarding the genetics and clinical aspects of the syndromic and nonsyndromic forms of pheochromocytoma/paraganglioma aiming to provide an algorithm for genetic testing.

Paragangliomas: update on differential diagnostic considerations, composite tumors, and recent genetic developments

Recent developments in molecular genetics have expanded the spectrum of disorders associated with pheochromocytomas (PCCs) and extra-adrenal paragangliomas (PGLs) and have increased the roles of pathologists in helping to guide patient care. At least 30% of these tumors are now known to be hereditary, and germline mutations of at least 10 genes are known to cause the tumors to develop. Genotype-phenotype correlations have been identified, including differences in tumor distribution, catecholamine production, and risk of metastasis, and types of tumors not previously associated with PCC/PGL are now considered in the spectrum of hereditary disease. Important new findings are that mutations of succinate dehydrogenase genes SDHA, SDHB, SDHC, SDHD, and SDHAF2 (collectively "SDHx") are responsible for a large percentage of hereditary PCC/PGL and that SDHB mutations are strongly correlated with extra-adrenal tumor location, metastasis, and poor prognosis. Further, gastrointestinal stromal tumors and renal tumors are now associated with SDHx mutations. A PCC or PGL caused by any of the hereditary susceptibility genes can present as a solitary, apparently sporadic, tumor, and substantial numbers of patients presenting with apparently sporadic tumors harbor occult germline mutations of susceptibility genes. Current roles of pathologists are differential diagnosis of primary tumors and metastases, identification of clues to occult hereditary disease, and triaging of patients for optimal genetic testing by immunohistochemical staining of tumor tissue for the loss of SDHB and SDHA protein. Diagnostic pitfalls are posed by morphological variants of PCC/PGL, unusual anatomic sites of occurrence, and coexisting neuroendocrine tumors of other types in some hereditary syndromes. These pitfalls can be avoided by judicious use of appropriate immunohistochemical stains. Aside from loss of staining for SDHB, criteria for predicting risk of metastasis are still controversial, and "malignancy" is diagnosed only after metastases have occurred. All PCCs/PGLs are considered to pose some risk of metastasis, and long-term follow-up is advised.

Genetics of hereditary head and neck paragangliomas

BACKGROUND

The purpose of this study was to give an overview on hereditary syndromes associated with head and neck paragangliomas (HNPGs).

METHODS

Our methods were the review and discussion of the pertinent literature.

RESULTS

About one third of all patients with HNPGs are carriers of germline mutations. Hereditary HNPGs have been described in association with mutations of 10 different genes. Mutations of the genes succinate dehydrogenase subunit D (SDHD), succinate dehydrogenase complex assembly factor 2 gene (SDHAF2), succinate dehydrogenase subunit C (SDHC), and succinate dehydrogenase subunit B (SDHB) are the cause of paraganglioma syndromes (PGLs) 1, 2, 3, and 4. Succinate dehydrogenase subunit A (SDHA), von Hippel-Lindau (VHL), and transmembrane protein 127 (TMEM127) gene mutations also harbor the risk for HNPG development. HNPGs in patients with rearranged during transfection (RET), neurofibromatosis type 1 (NF1), and MYC-associated factor X (MAX) gene mutations have been described very infrequently.

CONCLUSION

All patients with HNPGs should be offered a molecular genetic screening. This screening may usually be restricted to mutations of the genes SDHD, SDHB, and SDHC. Certain clinical parameters can help to set up the order in which those genes should be tested.

Current and future trends in the anatomical and functional imaging of head and neck paragangliomas

Head and neck paragangliomas (HNPGLs) account for approximately 3% of all paragangliomas (PGLs). Most often, HNPGLs are benign, nonsecreting, and slowly progressing. The initial physical examination and biochemical diagnosis usually adds very little to the proper diagnosis of these tumors, and, therefore, radiologists and nuclear medicine physicians play a pivotal role in providing the initial diagnosis, the locoregional staging, and the plan for detecting potential multicentric or metastatic lesions. Based on several current studies, the most accurate use of HNPGL-specific initial and subsequent imaging modalities must be guided by the knowledge of genetics and the specifically measured biochemical profile of these tumors for the proper management of these patients. Thus, this short review article presents the application of the most up-to-date anatomical and functional imaging approaches to HNPGLs tightly linked to the clinical management of these patients. Based on the most recent studies, 18F-FDOPA PET/CT has been shown to be a useful addition to anatomical imaging in the preoperative localization and molecular assessment of HNPGLs. It is estimated that the frequency of metabolically active PGLs on 18F-FDOPA PET/CT in this region is higher than 90%. For patients with hereditary PGL syndromes, (18)F-FDG-PET/CT should be reserved. Imaging of somatostatin receptors using Octreoscan or 68Ga-labeled somatostatin analogues plays an important role for selecting patients for targeted radiation therapy. This review also concludes that it is expected that in the near future, these patients will indeed benefit from new diagnostic approaches based on the identification of new targets by molecular profiling studies that will result in the development of novel PGL-specific radiopharmaceuticals.

The management of head-and-neck paragangliomas

Paragangliomas (PGLs) are tumours originating from neural crest-derived cells situated in the region of the autonomic nervous system ganglia. Head-and-neck PGLs (HNPGLs) originate from the sympathetic and parasympathetic paraganglia, most frequently from the carotid bodies and jugular, tympanic and vagal paraganglia, and are usually non-catecholamine secreting. Familial PGLs are considered to be rare, but recently genetic syndromes including multiple PGLs and/or phaeochromocytomas have been more thoroughly characterised. Nowadays, genetic screening for the genes frequently implicated in both familial and sporadic cases is routinely being recommended. HNPGLs are mostly benign, generally slow-growing tumours. Continuous growth leads to the involvement of adjacent neurovascular structures with increased morbidity rates and treatment-related complications. Optimal management mostly depends on tumour location, local involvement of neurovascular structures, estimated malignancy risk, patient age and general health. Surgery is the only treatment option offering the chance of cure but with significant morbidity rates, so a more conservative approach is usually considered, especially in the more difficult cases. Radiotherapy (fractionated or stereotactic radiosurgery) leads to tumour growth arrest and symptomatic improvement in the short term in many cases, but the long-term consequences are unclear. Early detection is essential in order to increase the chance of cure with a lower morbidity rate. The constant improvement in diagnostic imaging, surgical and radiation techniques has led to a safer management of these tumours, but there are still many therapeutic challenges, and no treatment algorithm has been agreed upon until now. The management of HNPGLs requires a multidisciplinary effort addressing the genetic, surgical, radiotherapeutic, oncological, neurological and endocrinological implications. Further progress in the understanding of their pathogenesis will lead to more effective screening and earlier diagnosis, both critical to successful treatment.

Identification of three new variants of SDHx genes in a cohort of Portuguese patients with extra-adrenal paragangliomas

BACKGROUND

Extra-adrenal paragangliomas (PGL) are rare neoplasms occurring in sporadic and familial forms, the latter mostly in association with germline mutations of SD- HB, SDHC or SDHD genes.

AIM

Characterize frequency and spectrum of germline mutations among a cohort of Portuguese patients with extra-adrenal PGL.

DESIGN

Molecular and clinical data were reviewed on 44 patients referred for genetic testing by a single laboratory.

RESULTS

Genetic analysis identified 11 patients with head and neck PGL (30.6%) positive for SD- Hx gene mutations (6 SDHD, 4 SDHB, 1 SDHC) and 4 patients with abdominal or pelvic PGL (50%) positive for SDHx gene mutations (4 SDHB). Large deletions made up about 20% of the mutations detected. Mutation carriers were younger and more frequently had multiple or malignant PGL than patients without mutations. Only 11% of the head and neck PGL were secretory. In contrast, 100% of the abdominal or pelvic PGL were secretory. Five patients had a malignant PGL (4 SDHB, 1 apparently sporadic). Three novel mutations were identified: two in the SDHD gene (c.411delT [p.Leu139PhefsX29] and c.371_390del20insGG [p.Ala124_Ala130delinsGly]), one in the SDHB gene (c.49A>G [p.Thr17Ala]). The SDHD variant c.411delT [p.Leu139PhefsX29] was present in 3 apparently unrelated patients. Molecular genetic testing of 22 relatives disclosed 16 mutation carriers.

CONCLUSIONS

Genetic analysis identified 15 patients (34.1%) and 16 at-risk individuals (72.7%) positive for SDHx gene mutations. The finding of three novel mutations broadens the mutational profile of the mitochondrial complex II succinate dehydrogenase genes reported in other large European series of patients with paragangliomas. Further studies are needed to clarify whether the high frequency of the SDHD variant c.411delT [p.Leu139PhefsX29] corresponds to a founder mutation.

Neurogenic tumors of soft tissue

Neurogenic tumors are an uncommon yet important category of soft tissue tumors in children and adolescents because of their frequent association with various genetic syndromes. The heterogeneous cellular composition of the peripheral nerve and the wide metaplastic capacity of the neural crest and its derivatives generate a variety of neoplasms with neurogenic differentiation. This article reviews the clinicopathologic features and differential diagnosis of neurogenic tumors in the first two decades of life, and highlights use of selected ancillary methods for diagnosis.

Pheochromocytoma and paraganglioma: understanding the complexities of the genetic background

Pheochromocytomas and paragangliomas (PCC/PGL) are tumors derived from the adrenal medulla or extra-adrenal ganglia, respectively. They are rare and often benign tumors that are associated with high morbidity and mortality due to mass effect and high circulating catecholamines. Although most PCCs and PGLs are thought to be sporadic, over one third are associated with 10 known susceptibility genes. Mutations in three genes causing well characterized tumor syndromes are associated with an increased risk of developing PCCs and PGLs, including VHL (von Hippel-Lindau disease), NF1 (Neurofibromatosis Type 1), and RET (Multiple Endocrine Neoplasia Type 2). Mutations in any of the succinate dehydrogenase (SDH) complex subunit genes (SDHA, SDHB, SDHC, SDHD) can lead to PCCs and PGLs with variable penetrance, as can mutations in the subunit cofactor, SDHAF2. Recently, two additional genes have been identified, TMEM127 and MAX. Although these tumors are rare in the general population, occurring in two to eight per million people, they are more commonly associated with an inherited mutation than any other cancer type. This review summarizes the known germline and somatic mutations leading to the development of PCC and PGL, as well as biochemical profiling for PCCs/PGLs and screening of mutation carriers.

Paragangliomas and paraganglioma syndromes

Paragangliomas are rare tumors of neural crest origin. They are benign in the majority of cases and are characterized by a strong vascularisation.

In the head and neck region they most commonly occur as carotid body tumors. Jugulotympanic and especially vagal paragangliomas are seen less frequently. Complete surgical resection represents the only curative treatment option even though resection of locally advanced tumors regularly results in lesions of the lower cranial nerves and major vessels.

Appoximately 30% of all head and neck paragangliomas (HNPs) are hereditary and associated with different tumor syndromes. The paraganglioma syndromes 1, 3 and 4 (PGL 1, 3 and 4) make up the majority of those familial cases. PGL 1 is associated with mutations of the succinate dehydrogenase subunit D (SDHD) gene, PGL 3 is caused by SDHC and PGL 4 by SDHB gene mutations. Multiple HNPs and the occurance of HNPs together with pheochromocytomas are seen in SDHD as well as SDHB mutation carriers. In patients with SDHB mutations the risk for the development of malignant paraganglial tumors is significantly higher compared to SDHC and SDHD patients as well as patients with sporadic tumors. SDHC mutation carriers almost exclusively present with benign HNP that are unifocal in the majority of cases. The role of transmission is autosomal dominant for all three symptoms. Interestingly, there is a “parent-of-origin-dependent-inheritance” in subjects with SDHD gene mutations. This means that the disease phenotype may only become present if the mutation is inherited through the paternal line. We recommend screening for mutations of the genes SDHB, SDHC and SDHD in patients with HNPs. Certain clinical parameters can help to set up the order in which the three genes should be tested.

Head and neck paragangliomas: genetic spectrum and clinical variability in 79 consecutive patients

Head and neck paragangliomas (HNPGLs) are neural crest-derived tumors. In comparison with paragangliomas located in the abdomen and the chest, which are generally catecholamine secreting (sPGLs) and sympathetic in origin, HNPGLs are, in fact, parasympathetic in origin and are generally nonsecreting. Overall, 79 consecutive patients with HNPGL were examined for mutations in SDHA, SDHB, SDHC, SDHD, SDHAF2, VHL, MAX, and TMEM127 genes by PCR/sequencing. According to a detailed family history (FH) and clinical, laboratory (including metanephrines), and instrumental examinations, patients were divided into three groups: a) patients with a positive FH for HNPGL (index cases only), b) patients with a negative FH and multiple HNPGLs (synchronous or metachronous) or HNPGL associated with an sPGL, and c) patients with negative FH and single HNPGL. The ten patients in group a) proved to be SDHD mutation carriers. The 16 patients in group b) proved to be SDHD mutation carriers. Among the 53 patients in group c), ten presented with germ-line mutations (three SDHB, three SDHD, two VHL, and two SDHAF2). An sPGL was found at diagnosis or followed up in five patients (6.3%), all were SDHD mutation carriers. No SDHC, SDHA, MAX, and TMEM127 mutations were found. In SDHD mutation carriers, none of the patients affected by HNPGL associated with sPGL presented missense mutations. In conclusion, a positive FH or the presence of multiple HNPGLs is a strong predictor for germ-line mutations, which are also present in 18.8% of patients carefully classified as sporadic. The most frequently mutated gene so far is SDHD but others, including SDHB, SDHAF2, and VHL, may also be affected.

Sporadic or familial head neck paragangliomas enrolled in a single center: clinical presentation and genotype/phenotype correlations

BACKGROUND

The purpose of this study was to investigate clinical features and prevalence of germline mutations of patients with head/neck paragangliomas.

METHODS

Genetic analysis on known susceptibility genes for paragangliomas (VHL, RET, SDHB, SDHC, SDHD, and SDHAF2) was performed in 17 consecutive patients with head/neck paraganglioma (age range, 14-82 years) and 17 relatives.

RESULTS

Head/neck paragangliomas were usually symptomatic with "mass effect" (88.2%), without family history (82.3%), often multifocal (41.2%), never functioning, and malignant. Germline mutations were detected in 7 of 17 patients (41%; 6 SDHD and 1 SDHB). Patients with mutations were younger, with head/neck paragangliomas usually multifocal and with higher biologic aggressiveness than wild-type subjects. To date, 4 families have been studied and the prevalence of carriers was elevated (58.8%). These mutated relatives (age range, 17-71 years) were disease-free, except 4 patients in whom multiple head/neck paragangliomas were detected.

CONCLUSION

Adequate morpho-functional screening and follow-up and, if possible, genetic testing is advisable in patients with head/neck paraganglioma.

SDHA immunohistochemistry detects germline SDHA gene mutations in apparently sporadic paragangliomas and pheochromocytomas

CONTEXT

Pheochromocytoma-paraganglioma syndrome is caused by mutations in SDHB, SDHC, and SDHD, encoding subunits of succinate dehydrogenase (SDH), and in SDHAF2, required for flavination of SDHA. A recent report described a patient with an abdominal paraganglioma, immunohistochemically negative for SDHA, and identified a causal germline mutation in SDHA.

OBJECTIVE

In this study, we evaluated the significance of SDHA immunohistochemistry in the identification of new patients with SDHA mutations.

SETTING

This study was performed in the Erasmus Medical Center in Rotterdam (The Netherlands) and the Université Paris Descartes in Paris (France).

METHODS

We investigated 316 pheochromocytomas and paragangliomas for SDHA expression. Sequence analysis of SDHA was performed on all tumors that were immunohistochemically negative for SDHA and on a subset of tumors immunohistochemically positive for SDHA.

RESULTS

Six tumors were immunohistochemically negative for SDHA. Four tumors from Dutch patients showed a germline c.91C → T SDHA gene mutation (p.Arg31X). Another tumor (from France) carried a germline SDHA missense mutation c.1753C → T (p.Arg585Trp). Loss of the wild-type SDHA allele was confirmed by loss of heterozygosity analysis. Sequence analysis of 35 SDHA immunohistochemically positive tumors did not reveal additional SDHA mutations.

CONCLUSIONS

Our results demonstrate that SDHA immunohistochemistry on paraffin-embedded tumors can reveal the presence of SDHA germline mutations and allowed the identification of SDHA-related tumors in at least 3% of patients affected by apparently sporadic (para)sympathetic paragangliomas and pheochromocytomas.

Hot flushes, hypertension and haemodialysis

Hypertension is common in patients with end stage renal disease. However, in patients non-responsive to standard measures to control the blood pressure, non-renal causes should be considered. We present the case of a patient on haemodialysis with difficult to control blood pressure.

VHL disease

von Hippel-Lindau disease (VHL) disease increases susceptibility to several malignancies, including renal cell carcinoma, haemangioblastomas of the central nervous system or retina and phaeochromocytomas. The VHL tumour suppressor gene, responsible for the disease, encodes for a major regulator of the hypoxic response by targeting the transcription factor hypoxia inducible factor (HIF) for degradation. In this review, we present a synopsis of clinical features of the disease and emphasise unique aspects of VHL syndrome in the paediatric population. Genotype-phenotype associations based on the risk of phaeochromocytoma have pointed to the existence of additional, HIF-independent functions of VHL that remain underexplored. We also examine the progress on these pleiotropic roles of VHL, which contribute to explain clinical features of VHL disease. These advances have important translational implications and are likely to offer a new host of therapeutic options to individuals affected by the disease in the future.

A current review of the etiology, diagnosis, and treatment of pediatric pheochromocytoma and paraganglioma

CONTEXT

Pheochromocytomas and paragangliomas (PHEO/PGL) are neuroendocrine tumors that arise from sympathetic and parasympathetic paraganglia. Diagnosed rarely during childhood, PHEO/PGL are nonetheless important clinical entities, particularly given our evolving understanding of their pathophysiology.

EVIDENCE ACQUISITION

We identified articles through the U.S. National Library of Medicine by using the search terms pheochromocytoma and paraganglioma. Results were narrowed to manuscripts that included children and studies related to the genetics of PHEO/PGL. Web-based resources for genetic disorders were also used. For all articles, we performed subsequent reference searches and verification of source data.

EVIDENCE SYNTHESIS

Up to 20% of PHEO/PGL are diagnosed in children. Most are functional tumors, and clinical presentation includes symptoms related to catecholamine hypersecretion and/or tumor mass effect. Increasingly, PHEO/PGL are identified during presymptomatic screening in children with genetic syndromes associated with PHEO/PGL (multiple endocrine neoplasia type 2, von Hippel-Lindau disease, and the paraganglioma syndromes). Plasma and/or urine metanephrines are the best diagnostic test for a functional tumor, and the management of pediatric patients is similar to adults. Genetic counseling should be undertaken in all cases. Although most pediatric PHEO/PGL are benign, these tumors can occasionally metastasize, a condition for which no curative treatment exists.

CONCLUSIONS

Although PHEO/PGL are rarely diagnosed during childhood, the pediatric provider should be able to recognize and screen for such tumors, particularly in the context of a known genetic predisposition. Optimal care of these children includes a multidisciplinary team approach at centers experienced in the evaluation and treatment of these uncommon yet fascinating endocrine neoplasms.