15 YEARS OF PARAGANGLIOMA: Genetics and mechanism of pheochromocytoma-paraganglioma syndromes characterized by germline SDHB and SDHD mutations

A retrospective study of paraganglioma of the urinary bladder and literature review

Objective

To review and summarize the characteristics and therapy of paraganglioma of the urinary bladder (PUB).

Method

Patients who underwent the operation in Peking Union Medical College Hospital between January 2012 and December 2021 were reviewed for this retrospective study.

Results

A total of 29 patients, comprising 9 (31%) men and 20 (69%) women, were included. The main manifestations were hypertension, palpitation, and micturition syncope. Eight patients had an increased 24-h urinary catecholamine, and seven of them had increased norepinephrine. Normetanephrine in seven patients was increased. Six of 18 metaiodobenzylguanidine and 8 of 22 octreotide scans were positive. In total, 15 cases underwent laparoscopic partial cystectomy and 14 underwent transurethral resection of bladder tumor. In all patients, the immunohistochemical index of Melan-A, AE1/AE3, and α-inhibin were negative, and chromogranin A, S-100, and succinate dehydrogenase were positive. The Ki-67 of 28/29 cases was under 5%, and 1 case with a Ki-67 of 20% was diagnosed with malignant PUB. A total of 27 patients had a regular follow-up, 2 patients were lost during the follow-up, 3 patients had a recurrence, and 1 of these patients died within 1 year of surgery. The symptoms all disappeared or were relieved after the surgery.

Conclusion

The transurethral surgery approach fits PUB tumors with a size <3 cm or that protrudes into the bladder and can significantly reduce the postoperative hospital stay. Early detection and treatment are effective, and regular review is necessary after the surgery.

Reduced Risk of Corporal Tumors in Patients With Head and Neck Paragangliomas With p.Pro81Leu Mutations

OBJECTIVE

Patients with head and neck paragangliomas who are positive for the SDHD p.Pro81Leu (P81L) mutation are thought to have a distinct phenotype from other SDHx mutations, but few studies have focused on this mutation. The objective of this study was to determine the hazard of developing a second primary, metastatic, or recurrent paraganglioma in SDHx patients with or without P81L.

STUDY DESIGN

Retrospective chart review of 60 patients with head and neck paragangliomas and genetic testing, followed for a median of 9 years.

SETTING

Single academic medical center.

METHODS

Univariable Cox proportional hazards regression evaluated second primary and recurrent paragangliomas in patients with SDHD P81L, SDHx non-P81L, and nonhereditary paraganglioma.

RESULTS

This series comprised 31 patients without SDHx, 14 with SDHD P81L, and 15 with other SDHx mutations. At a median 9 years of follow-up, corporal (not head and neck) second primary paragangliomas occurred in 31% of patients with SDHx non-P81L mutations, compared with 0% and 4% of patients with SDHD P81L and without SDHx mutations, respectively. Second corporal paragangliomas were more likely in patients with SDHx non-P81L mutations than in those without a mutation (hazard ratio = 5.461, 95% confidence interval: 0.596-50.030, p = .13).

CONCLUSION

This is the first study to report a lower likelihood of corporal tumors for patients with head and neck paragangliomas with SDH mutations positive for P81L. Larger studies are needed to determine if head and neck paraganglioma patients with P81L qualify for less intensive imaging surveillance to screen for second primary paragangliomas outside the head and neck.

Complex II Biology in Aging, Health, and Disease

Aging is associated with a decline in mitochondrial function which may contribute to age-related diseases such as neurodegeneration, cancer, and cardiovascular diseases. Recently, mitochondrial Complex II has emerged as an important player in the aging process. Mitochondrial Complex II converts succinate to fumarate and plays an essential role in both the tricarboxylic acid (TCA) cycle and the electron transport chain (ETC). The dysfunction of Complex II not only limits mitochondrial energy production; it may also promote oxidative stress, contributing, over time, to cellular damage, aging, and disease. Intriguingly, succinate, the substrate for Complex II which accumulates during mitochondrial dysfunction, has been shown to have widespread effects as a signaling molecule. Here, we review recent advances related to understanding the function of Complex II, succinate signaling, and their combined roles in aging and aging-related diseases.

Genetic impairment of succinate metabolism disrupts bioenergetic sensing in adrenal neuroendocrine cancer

Metabolic dysfunction mutations can impair energy sensing and cause cancer. Loss of function of the mitochondrial tricarboxylic acid (TCA) cycle enzyme subunit succinate dehydrogenase B (SDHB) results in various forms of cancer typified by pheochromocytoma (PC). Here we delineate a signaling cascade where the loss of SDHB induces the Warburg effect, triggers dysregulation of [Ca²⁺]_i, and aberrantly activates calpain and protein kinase Cdk5, through conversion of its cofactor from p35 to p25. Consequently, aberrant Cdk5 initiates a phospho-signaling cascade where GSK3 inhibition inactivates energy sensing by AMP kinase through dephosphorylation of the AMP kinase γ subunit, PRKAG2. Overexpression of p25-GFP in mouse adrenal chromaffin cells also elicits this phosphorylation signaling and causes PC. A potent Cdk5 inhibitor, MRT3-007, reverses this phospho-cascade, invoking a senescence-like phenotype. This therapeutic approach halted tumor progression in vivo. Thus, we reveal an important mechanistic feature of metabolic sensing and demonstrate that its dysregulation underlies tumor progression in PC and likely other cancers.

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.

Clinical and histopathological principles for the diagnosis of a recurrent paraganglioma of the jugular foramen initially diagnosed as a middle ear adenoma: illustrative case

BACKGROUND

Paragangliomas (PGLs) are rare neoplasms that may be associated with hereditary PGL syndromes and variable risk of metastasis. Middle ear adenomas are extremely rare tumors with no known hereditary predisposition and extremely low risk of metastasis. Although often easily differentiated, they may share clinical and pathological features that misdirect and confuse the diagnosis.

OBSERVATIONS

The authors discussed a 35-year-old woman with left-sided hearing loss and bleeding from the external ear canal who presented to an outside hospital. She underwent resection of a middle ear and mastoid mass, initially diagnosed as a middle ear adenoma with neuroendocrine features, with later mastoidectomy and ligation of the sigmoid sinus with microsurgical excision of persistent tumor in the jugular foramen and temporal bone. Histopathologically, her tumor was vascular, composed of benign-appearing epithelioid cells with “salt and pepper” neuroendocrine chromatin arranged in vague nests. Lesional cells were GATA3-immunopositive, glucagon-negative, and succinate dehydrogenase-immunonegative, consistent with PGL rather than middle ear adenoma, and required further workup for hereditary PGL syndromes.

LESSONS

This case demonstrates potential challenges in differentiating a PGL from a middle ear adenoma. The authors offer clinical, histopathological, and imaging principles to aid in diagnosis and workup.

Sunitinib Treatment for Advanced Paraganglioma: Case Report of a Novel SDHD Gene Mutation Variant and Systematic Review of the Literature

Background

Paragangliomas (PGLs) are neuroendocrine neoplasms arising from chromaffin cells of sympathetic or parasympathetic paraganglia. Systemic therapies have been used only in metastatic PGLs. Antiangiogenic agents, such as sunitinib, could be a viable therapeutic choice in the subgroup of patients with SDH-positive PGLs. We describe the case of a man with Familial Paraganglioma Syndrome type 1 (FPGL) related to a novel mutation in SDHD gene treated with sunitinib. Furthermore, we performed a systematic review of the literature aimed to address the following question: is sunitinib treatment effective in patients with advanced/progressive/metastatic PGL?

Methods

We performed a data search using MEDLINE, Cochrane Library, and Scopus between April 2019 and September 2020. We included studies reporting data on clinical or biological characteristics, or clinical outcomes of patients with PGLs treated with sunitinib.

Results

The search leaded to the selection of 25 publications. Data from case reports and case series showed that disease control rate (DCR = stable disease + partial response + complete response) was achieved in 34.7% of cases under sunitinib treatment. In 39% of patients DCR was followed by progressive disease (PD) or tumor relapse, 26.1% patients showed PD. Data from clinical trials showed that DCR was 83%, and the median progression free survival was 13.4 months.

Discussion

Data from the present literature review suggested that sunitinib could be a viable therapeutic option in advanced/progressive/metastatic inoperable PGLs. However, further trials on the efficacy of sunitinib in FPGL and sporadic PGL are needed.

SDHB-Associated Paraganglioma Syndrome in Africa-A Need for Greater Genetic Testing

A germline mutation is identified in almost 40% of pheochromocytoma/paraganglioma (PPGL) syndromes. Genetic testing and counseling are essential for the management of index cases as well as presymptomatic identification and preemptive management of affected family members. Mutations in the genes encoding the mitochondrial enzyme succinate dehydrogenase (SDH) are well described in patients with hereditary PPGL. Among patients of African ancestry, the prevalence, phenotype, germline mutation spectrum, and penetrance of SDH mutations is poorly characterized. We describe a multifocal paraganglioma in a young African male with an underlying missense succinate dehydrogenase subunit B (SDHB) mutation and a history of 3 first-degree relatives who died at young ages from suspected cardiovascular causes. The same SDHB mutation, Class V variant c.724C>A p.(Arg242Ser), was detected in one of his asymptomatic siblings. As there are limited data describing hereditary PPGL syndromes in Africa, this report of an SDHB-associated PPGL is a notable contribution to the literature in this growing field. Due to the noteworthy clinical implications of PPGL mutations, this work highlights the existing need for broader genetic screening among African patients with PPGL despite the limited healthcare resources available in this region.

Prognostic Nomograms for Predicting Overall Survival and Cancer-Specific Survival of Patients With Malignant Pheochromocytoma and Paraganglioma

BACKGROUND

Malignant pheochromocytoma and paraganglioma (PPGL) are rare tumors with few prognostic tools. This study aimed to construct nomograms for predicting 3- and 5-year survival for patients with malignant PPGL.

METHODS

The patient data was retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. A total of 764 patients diagnosed with malignant PPGL from 1975 to 2016 were included in this study. The patients were randomly divided into two cohorts; the training cohort (n = 536) and the validation cohort (n = 228). Univariate analysis, Lasso regression, and multivariate Cox analysis were used to identify independent prognostic factors, which were then utilized to construct survival nomograms. The nomograms were used to predict 3- and 5-year overall survival (OS) and cancer-specific survival (CSS) for patients with malignant PPGL. The prediction accuracy of the nomogram was assessed using the concordance index (C-index), receiver operating characteristic (ROC) curves and calibration curves. Decision curve analysis (DCAs) was used to evaluate the performance of survival models.

RESULTS

Age, gender, tumor type, tumor stage, or surgery were independent prognostic factors for OS in patients with malignant PPGL, while age, tumor stage, or surgery were independent prognostic factors for CSS (P <.05). Based on these factors, we successfully constructed the OS and CSS nomograms. The C-indexes were 0.747 and 0.742 for the OS and CSS nomograms, respectively. In addition, both the calibration curves and ROC curves for the model exhibited reliable performance.

CONCLUSION

We successfully constructed nomograms for predicting the OS and CSS of patients with malignant PPGL. The nomograms could inform personalized clinical management of the patients.

A narrative review of the role of fibroblasts in the growth and development of neurogenic tumors

Neurogenic tumors, a group of tumors arising from neurogenic elements, could theoretically appear in every region of human bodies wherever nerves exist. Patients with these tumors suffer from both physical and psychological problems. However, as a relatively rare tumor type, therapies are relatively scarce for these tumors due to the limited understanding of the underlying mechanisms. Recently, a tailored tumor microenvironment containing multiple types of nonneoplastic cells has been considered to play an essential role in tumor survival, growth, and metastasis. Fibroblasts are a crucial constituent of the tumor microenvironment and have been found to promote tumor growth via multiple mechanisms. However, the understanding of the pivotal role of fibroblasts in the tumorigenesis and development of the neurogenic tumors is still incomplete, and studies in this area show differences in rates of progression among different neurogenic tumor subtypes. Nevertheless, all these neural crest-originated neoplasms show some similarities in the tumor microenvironment, indicating that studies of one subtype of neurogenic tumor might assist in clarifying the underlying mechanisms of other subtypes. This review aims to provide current studies showing the impacts of fibroblasts on major benign/malignant subtypes of neurogenic tumors, including neurofibromatosis type 1, neuroblastomas, pheochromocytomas, and malignant peripheral nerve sheath tumors. Multiple related mechanisms such as the fibroblasts regulating the tumor inflammation, angiogenesis, metabolism, and microenvironment establishment have been studied up to present. Consistently, we focus on how studies on various subtypes of these neurogenic tumors contribute to the establishment of potential future directions for further studies in this area. Clarifying the underlying mechanisms by which fibroblasts promote the growth and metastasis of neurogenic tumors will indicate new therapeutic targets for further clinical treatment.

Intrinsic and Extrinsic Modulators of the Epithelial to Mesenchymal Transition: Driving the Fate of Tumor Microenvironment

The epithelial to mesenchymal transition (EMT) is an evolutionarily conserved process. In cancer, EMT can activate biochemical changes in tumor cells that enable the destruction of the cellular polarity, leading to the acquisition of invasive capabilities. EMT regulation can be triggered by intrinsic and extrinsic signaling, allowing the tumor to adapt to the microenvironment demand in the different stages of tumor progression. In concomitance, tumor cells undergoing EMT actively interact with the surrounding tumor microenvironment (TME) constituted by cell components and extracellular matrix as well as cell secretome elements. As a result, the TME is in turn modulated by the EMT process toward an aggressive behavior. The current review presents the intrinsic and extrinsic modulators of EMT and their relationship with the TME, focusing on the non-cell-derived components, such as secreted metabolites, extracellular matrix, as well as extracellular vesicles. Moreover, we explore how these modulators can be suitable targets for anticancer therapy and personalized medicine.

Imaging Features of Succinate Dehydrogenase-deficient Pheochromocytoma-Paraganglioma Syndromes

Pheochromocytoma (PC) and paraganglioma (PGL) are rare neuroendocrine tumors that occur throughout the body from the base of the skull to the pelvis. Sympathetic catecholamine-secreting tumors may be associated with hyperadrenergic symptoms and long-term morbidity if they are untreated. Typically biochemically silent, head and neck PGLs may result in cranial nerve palsies and symptoms due to localized mass effect. Tumors can arise sporadically or as part of an inheritable PC-PGL syndrome. Up to 40% of tumors are recognized to be associated with germline mutations in an increasing array of susceptibility genes, including those that appear to arise sporadically. Most commonly, up to 25% of all PC-PGLs are associated with mutations in one of the succinate dehydrogenase (SDH) enzyme subunit genes. The resulting familial PC-PGL syndrome varies according to the affected enzyme subunit (most commonly SDHB and SDHD mutations) with respect to tumor prevalence, location, age of onset, and risk of malignancy. Patients with SDH enzyme mutations have increased lifetime risk of developing multifocal tumors and malignancy. Early recognition of individuals at high risk, genetic testing, screening of family members, and lifelong surveillance programs are recommended, but not without health, economic, and psychologic implications. Anatomic and functional imaging is key to diagnosis, staging, treatment planning, and lifelong surveillance of these individuals. Radiologists must be aware of the imaging appearance of these varied tumors.^©RSNA, 2019.

The role of mitochondrial-related nuclear genes in age-related common disease

Mitochondria are critical organelles that provide energy as ATP to the cell. Besides 37 genes encoded by mitochondrial genome, it has been estimated that over 1500 nuclear genes are required for mitochondrial structure and function. Thus, mutations of many genes in the nuclear genome cause dysfunction of mitochondria that can lead to many severe conditions. Mitochondrial dysfunction often results in reduced ATP synthesis, higher levels of reactive oxygen species (ROS), imbalanced mitochondrial dynamics, and other detrimental effects. In addition to rare primary mitochondrial disorders, these mitochondrial-related genes are often associated with many common diseases. For example, in neurodegenerative diseases such as Parkinson's, Alzheimer's, and Huntington disease, mitochondrialand energy metabolism abnormalities can greatly affect brain function. Cancer cells are also known to exhibit repressed mitochondrial ATP production in favor of glycolysis, which fuels the aggressive proliferation and metastasis of tumor tissues, leading many to speculate on a possible relationship between compromised mitochondrial function and cancer. The association between mitochondrial dysfunction and diabetes is also unsurprising, given the organelle's crucial role in cellular energy utilization. Here, we will discuss the multiple lines of evidence connecting mitochondrial dysfunction associated with mitochondria-related nuclear genes to many of the well-known disease genes that also underlie common disease.

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.

Natural History and Management of Familial Paraganglioma Syndrome Type 1: Long-Term Data from a Large Family

Head and neck paragangliomas are the most common clinical features of familial paraganglioma syndrome type 1 caused by succinate dehydrogenase complex subunit D (SDHD) mutation. The clinical management of this syndrome is still unclear. In this study we propose a diagnostic algorithm for SDHD mutation carriers based on our family case series and literature review. After genetic diagnosis, first evaluation should include biochemical examination and whole-body imaging. In case of lesion detection, nuclear medicine examination is required for staging and tumor characterization. The study summarizes the diagnostic accuracy of different functional imaging techniques in SDHD mutation carriers. 18F-3,4-dihydroxyphenylalanine (18F-DOPA) positron emission tomography (PET)-computed tomography (CT) is considered the gold standard. If it is not available, 123I-Metaiodobenzylguanidine (MIBG) could be used also for predicting response to radiometabolic therapy. 18F-fluoro-2-deoxy-D-glucose (18F-FDG) PET-CT has a prognostic role since high uptake identifies more aggressive cases. Finally, 68Ga-peptides PET-CT is a promising diagnostic technique, demonstrating the best diagnostic accuracy in our and in other published case series, even if this finding still needs to be confirmed in larger studies. Periodic follow-up should consist of annual biochemical and ultrasonographic screening and biannual magnetic resonance examination to identify biochemical silent tumors early.

Recurrence and Progression of Head and Neck Paragangliomas after Treatment

OBJECTIVE

To characterize the recurrence of head and neck paragangliomas and the factors associated with disease progression after treatment.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary care center.

SUBJECTS AND METHODS

In total, 173 adults with 189 paragangliomas (41.3% carotid body, 29.1% glomus jugulare, 19.0% glomus tympanicum, and 10.6% glomus vagale) treated between 1990 and 2010 were evaluated to determine the incidence and risk of recurrence using Cox proportional hazards.

RESULTS

The mean (SD) follow-up duration was 8.6 (9.1) years. The incidence was 2.92 recurrences per 100 person-years. The rate of recurrence was 8.2% (95% confidence interval [CI], 3.7-12.7) after 4 years and 17.1% (95% CI, 10.2-24.0) after 10 years. Glomus jugulare tumors were more likely to recur (hazard ratio [HR], 3.69; 95% CI, 1.70-8.01; P < .001) while carotid body tumors were less likely (HR, 0.44; 95% CI, 0.21-0.97; P = .041). Radiation had a lower risk of recurrence or progression compared to surgical excision (HR, 0.30; 95% CI, 0.10-.94; P = .040). Recurrence was associated with right-sided paragangliomas (HR, 3.60; 95% CI, 1.63-7.75; P = .001). The median time to recurrence was 18.4 years. Six (3.2%) patients developed metastasis, which was more common with local recurrence (9.5% vs 1.4%, P = .015).

CONCLUSIONS

Recurrence is more common with glomus jugulare tumors and less common with carotid body tumors. Radiation may have a lower risk of recurrence or progression than surgery for some paraganglioma types. Metastasis is rare but more likely with recurrent disease. Surveillance neck imaging is recommended every several years for decades after treatment.

SDHx-related pheochromocytoma/paraganglioma - genetic, clinical, and treatment outcomes in a series of 30 patients from a single center

PURPOSE

Germline mutations in the four genes that encode the succinate dehydrogenase complex (SDHx) are a risk factor for developing pheochromocytomas and/or paragangliomas. The precise genotype-phenotype correlations are still uncertain and the most common SDHx genetic defects in the Portuguese population are poorly described. The objectives of our study were to characterize the genetic alterations, clinical features, and treatment outcomes of a cohort of SDHx-related pheochromocytomas and/or paragangliomas patients.

METHODS

Single center, retrospective analysis based on the presence of a SDHx mutation in cases diagnosed from 1986 until October 2016.

RESULTS

Thirty cases were included. The mean age at diagnosis was 36.8 years (±15.4 years) and 53.3% were females. Remission was observed in 33.3% and stable disease (including partial responses) in 53.0%. SDHC and SDHD patients were prone to develop single and multiple head and neck paragangliomas, respectively. SDHB patients carried an increased risk of malignancy. Deletions in SDHB exon-1 and in SDHD exon-4 were the most common genetic findings. SDHB patients and head and neck paragangliomas had the worse prognosis, the former related to malignancy, and the latter to cranial nerve deficits, unresectable disease, and multimodality interventions. Peptide receptor radionuclide therapy and radioactive iodine MIBG therapy proved to be ineffective. Radiotherapy represented a good alternative in unresectable head and neck paragangliomas and in bone metastases.

CONCLUSION

This single center study is the most complete Portuguese cohort in the literature and helps to understand the behavior of tumors based on their genotype and anatomical location.

Mitochondrial DNA Variants and Common Diseases: A Mathematical Model for the Diversity of Age-Related mtDNA Mutations

The mitochondrion is the only organelle in the human cell, besides the nucleus, with its own DNA (mtDNA). Since the mitochondrion is critical to the energy metabolism of the eukaryotic cell, it should be unsurprising, then, that a primary driver of cellular aging and related diseases is mtDNA instability over the life of an individual. The mutation rate of mammalian mtDNA is significantly higher than the mutation rate observed for nuclear DNA, due to the poor fidelity of DNA polymerase and the ROS-saturated environment present within the mitochondrion. In this review, we will discuss the current literature showing that mitochondrial dysfunction can contribute to age-related common diseases such as cancer, diabetes, and other commonly occurring diseases. We will then turn our attention to the likely role that mtDNA mutation plays in aging and senescence. Finally, we will use this context to develop a mathematical formula for estimating for the accumulation of somatic mtDNA mutations with age. This resulting model shows that almost 90% of non-proliferating cells would be expected to have at least 100 mutations per cell by the age of 70, and almost no cells would have fewer than 10 mutations, suggesting that mtDNA mutations may contribute significantly to many adult onset diseases.

Non-canonical roles for metabolic enzymes and intermediates in malignant progression and metastasis

Metabolic alterations are established as a hallmark of cancer. Such hallmark changes in cancer metabolism are characterized by reprogramming of energy-producing pathways and increases in the generation of biosynthetic intermediates to meet the needs of rapidly proliferating tumor cells. Various metabolic phenotypes such as aerobic glycolysis, increased glutamine consumption, and lipolysis have also been associated with the process of metastasis. However, in addition to the energy and biosynthetic alterations, a number of secondary functions of enzymes and metabolites are emerging that specifically contribute to metastasis. Here, we describe atypical intracellular roles of metabolic enzymes, extracellular functions of metabolic enzymes, roles of metabolites as signaling molecules, and epigenetic regulation mediated by altered metabolism, all of which can affect metastatic progression. We highlight how some of these mechanisms are already being exploited for therapeutic purposes, and discuss how others show similar potential.

[Hereditary pheochromocytoma and paraganglioma: screening and follow-up strategies in asymptomatic mutation carriers]

The management of pheochromocytoma and paraganglioma has deeply evolved over the last years due to the discovery of novel genes of susceptibility, especially SDHx, MAX and TMEM127. While the modalities of diagnosis and management of patients presenting with hereditary pheochromocytoma and paraganglioma are now well defined, screening and follow-up strategies for asymptomatic mutation carriers remain a matter of debate. This raises major questions as these asymptomatic patients will require a lifelong follow-up. The aim of this review is an attempt to give insights on the optimal screening and follow-up strategies of asymptomatic carriers of SDHx, MAX and TMEM127 mutations, with additional thoughts on the forensic and psychological aspects of the management of such patients with rare diseases.

Network-based analysis of oligodendrogliomas predicts novel cancer gene candidates within the region of the 1p/19q co-deletion

Oligodendrogliomas are primary human brain tumors with a characteristic 1p/19q co-deletion of important prognostic relevance, but little is known about the pathology of this chromosomal mutation. We developed a network-based approach to identify novel cancer gene candidates in the region of the 1p/19q co-deletion. Gene regulatory networks were learned from gene expression and copy number data of 178 oligodendrogliomas and further used to quantify putative impacts of differentially expressed genes of the 1p/19q region on cancer-relevant pathways. We predicted 8 genes with strong impact on signaling pathways and 14 genes with strong impact on metabolic pathways widespread across the region of the 1p/19 co-deletion. Many of these candidates (e.g. ELTD1, SDHB, SEPW1, SLC17A7, SZRD1, THAP3, ZBTB17) are likely to push, whereas others (e.g. CAP1, HBXIP, KLK6, PARK7, PTAFR) might counteract oligodendroglioma development. For example, ELTD1, a functionally validated glioblastoma oncogene located on 1p, was overexpressed. Further, the known glioblastoma tumor suppressor SLC17A7 located on 19q was underexpressed. Moreover, known epigenetic alterations triggered by mutated SDHB in paragangliomas suggest that underexpressed SDHB in oligodendrogliomas may support and possibly enhance the epigenetic reprogramming induced by the IDH-mutation. We further analyzed rarely observed deletions and duplications of chromosomal arms within oligodendroglioma subcohorts identifying putative oncogenes and tumor suppressors that possibly influence the development of oligodendroglioma subgroups. Our in-depth computational study contributes to a better understanding of the pathology of the 1p/19q co-deletion and other chromosomal arm mutations. This might open opportunities for functional validations and new therapeutic strategies.

Co-Occurrence of Pheochromocytoma-Paraganglioma and Cyanotic Congenital Heart Disease: A Case Report and Literature Review

Pheochromocytoma and paraganglioma (PHEO-PGL) and cyanotic congenital heart disease (CCHD) are both rare diseases. We reported a 30-year-old patient with a right adrenal gland nodule and a retroperitoneal mass and history of functional single atrium and ventricle. ¹²³I-metaiodobenzylguanidine scintigraphy showed intense uptake in both lesions. Laboratory investigation demonstrated elevated urinary norepinephrine. Preoperative α-blockade was initiated. A successful open resection of right adrenal and retroperitoneal masses was performed. Pathological examination confirmed PHEO-PGL. Postoperative urinary norepinephrine returned to normal level. A systematic case review in English publications in PubMed and EMBASE suggested a hypothesis that there may exist a possible link between PHEO-PGL and hypoxia from CCHD, which was also indicated in our case. Due to higher risk for PHEO-PGL, a lower threshold of suspicion should be considered in CCHD patients. Therefore, active screening and early treatment of PHEO-PGL are recommended in CCHD patients and clinicians should keep on a long-term follow-up to monitor PHEO-PGL recurrence if hypoxia is not corrected.

N-Glycomic Profiling of Pheochromocytomas and Paragangliomas Separates Metastatic and Nonmetastatic Disease

CONTEXT

No effective methods for separating primary pheochromocytomas and paragangliomas with metastatic potential are currently available. The identification of specific asparagine-linked glycan (N-glycan) structures, which are associated with metastasized pheochromocytomas and paragangliomas, may serve as a diagnostic tool.

OBJECTIVE

To identify differences in N-glycomic profiles of primary metastasized and nonmetastasized pheochromocytomas and paragangliomas.

SETTING

This study was conducted at Helsinki University Hospital, University of Helsinki, and Glykos Finland Ltd. and included 16 pheochromocytomas and paragangliomas: 8 primary metastasized pheochromocytomas or paragangliomas and 8 nonmetastasized tumors.

METHODS

N-glycan structures were analyzed with matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) profiling of formalin-fixed, paraffin-embedded tissue samples.

MAIN OUTCOME MEASURE

N-glycan profile of tumor tissue.

RESULTS

Four groups of neutral N-glycan signals were more abundant in metastasized tumors than in nonmetastasized tumors: complex-type N-glycan signals of cancer-associated terminal N-acetylglucosamine, multifucosylated glycans (complex fucosylation), hybrid-type N-glycans, and fucosylated pauci-mannose-type N-glycans. Three groups of acidic N-glycans were more abundant in metastasized tumors: multifucosylated glycans, acid ester-modified (sulfated or phosphorylated) glycans, and hybrid-type/monoantennary N-glycans. Fucosylation and complex fucosylation were significantly more abundant in metastasized paragangliomas and pheochromocytomas than in nonmetastasized tumors for individual tests but were over the false positivity critical rate, when adjusted for multiplicity testing.

CONCLUSIONS

MALDI-TOF MS profiling of primary pheochromocytomas and paragangliomas can identify diseases with metastatic potential based on their different N-glycan profiles. Thus, malignancy-linked N-glycan structures may serve as potential diagnostic tools for pheochromocytomas and paragangliomas.

The microenvironment induces collective migration in SDHB-silenced mouse pheochromocytoma spheroids

Pheochromocytomas (Pheos) and paragangliomas (PGLs) are neuroendocrine tumors. Approximately 30-40% of Pheos/PGLs are due to germline mutations in one of the susceptibility genes, including those encoding the succinate dehydrogenase subunits A-D (SDHA-D). Up to 2/3 of patients affected by SDHB mutated Pheo/PGL develop metastatic disease with no successful cure at present. Here, for the first time, we evaluated the effects of SDHB silencing in a three dimension (3D) culture using spheroids of a mouse Pheo cell line silenced or not (wild type/wt/control) for the SDHB subunit. We investigated the role of the microenvironment on spheroid growth and migration/invasion by co-culturing SDHB-silenced or wt spheroids with primary cancer-activated fibroblasts (CAFs). When spheroids were co-cultured with fibroblasts, SDHB-silenced cells showed a significant increase in matrigel invasion as demonstrated by the computation of the migratory areas (P < 0.001). Moreover, cells detaching from the SDHB-silenced spheroids moved collectively, unlike the cells of wt spheroids that moved individually. Additionally, SDHB-silenced spheroids developed long filamentous formations along which clusters of cells migrated far away from the spheroid, whereas these structures were not present in wt spheroids. We found that lactate, largely secreted by CAFs, plays a specific role in promoting migration only of SDHB-silenced cells. In this study, we demonstrated that SDHB silencing per se increases tumor cell migration/invasion and that microenvironment, as represented by CAFs, plays a pivotal role in enhancing collective migration/invasion in Pheo SDHB-silenced tumor cells, suggesting their role in increasing the tumor metastasizing potential.

Functioning metastatic paraganglioma of the urinary bladder in a 10-year-old child

Paragangliomas of the urinary bladder are very rare tumours representing less than 1% of bladder tumours. Preoperative diagnosis is essential to avoid perioperative complications related to catecholamine release. A high index of suspicion should be maintained when the classical symptoms of voiding-related paroxysms of headache, palpitation and dizziness are present. We present a rare case of malignant paraganglioma of the urinary bladder in a 10-year-old boy. The patient had the classic presentation. We review the radiological diagnostic tools and findings of this rare entity.

Malignant pheochromocytoma-paraganglioma: pathogenesis, TNM staging, and current clinical trials

PURPOSE OF REVIEW

Pheochromocytomas and paragangliomas (PPGs) are rare neuroendocrine tumors. Over the last 15 years, substantial progress has been made toward understanding the clinical aspects and molecular origins of this disease. Nevertheless, predicting and managing malignancy remains the biggest challenge in clinical practice. The natural history of patients with malignant PPGs has not yet been described, and their prognosis varies. Currently, the diagnosis of malignant PPGs relies on the presence of metastases, by which time the disease is usually advanced. Better understanding of the clinical and molecular characteristics of patients with malignant PPGs has spurred several prospective clinical trials.

RECENT FINDINGS

Several molecular targeted therapies, a novel radiopharmaceutical medication that targets the catecholamine transporter, and immunotherapy are under evaluation for the treatment of patients with malignant PPGs. Furthermore, the identification of clinical predictors of malignancy and survival has led to the first TNM staging classification for PPGs.

SUMMARY

Prospective clinical trials are providing patients with therapeutic options beyond systemic chemotherapy. The knowledge derived from these trials and from the evaluation of the TNM staging in clinical practice will help to clarify how to most effectively treat malignant PPGs.

Metabolic reprogramming and epithelial-to-mesenchymal transition in cancer

Several lines of evidence indicate that during transformation epithelial cancer cells can acquire mesenchymal features via a process called epithelial-to-mesenchymal transition (EMT). This process endows cancer cells with increased invasive and migratory capacity, enabling tumour dissemination and metastasis. EMT is associated with a complex metabolic reprogramming, orchestrated by EMT transcription factors, which support the energy requirements of increased motility and growth in harsh environmental conditions. The discovery that mutations in metabolic genes such as FH, SDH and IDH activate EMT provided further evidence that EMT and metabolism are intertwined. In this review, we discuss the role of EMT in cancer and the underpinning metabolic reprogramming. We also put forward the hypothesis that, by altering chromatin structure and function, metabolic pathways engaged by EMT are necessary for its full activation.

Nasal Cavity Paraganglioma: Literature Review and Discussion of a Rare Case

Paragangliomas can be found from the skull base to the sacrum. Sinonasal paragangliomas are infrequent. A 16-year-old female reported spontaneous discrete bilateral epistaxis once a month beginning when she was 3 years of age. Computed tomography showed an expansive hypervascular mass occupying the right nasal cavity and nasopharynx. Sinonasal paragangliomas usually occur in middle-aged women. Radiologic investigation is essential for the diagnosis of sinonasal paragangliomas and evaluating extension of the lesion. Endoscopic and conventional approaches are effective, and preoperative embolization is paramount for reducing bleeding risk. Histopathological features cannot differentiate benign from malignant paragangliomas, and since metastasis may eventually occur, follow-up must be carried out for a long period of time.

Consensus Statement on next-generation-sequencing-based diagnostic testing of hereditary phaeochromocytomas and paragangliomas

Phaeochromocytomas and paragangliomas (PPGLs) are neural-crest-derived tumours of the sympathetic or parasympathetic nervous system that are often inherited and are genetically heterogeneous. Genetic testing is recommended for patients with these tumours and for family members of patients with hereditary forms of PPGLs. Due to the large number of susceptibility genes implicated in the diagnosis of inherited PPGLs, next-generation sequencing (NGS) technology is ideally suited for carrying out genetic screening of these individuals. This Consensus Statement, formulated by a study group comprised of experts in the field, proposes specific recommendations for the use of diagnostic NGS in hereditary PPGLs. In brief, the study group recommends target gene panels for screening of germ line DNA, technical adaptations to address different modes of disease transmission, orthogonal validation of NGS findings, standardized classification of variant pathogenicity and uniform reporting of the findings. The use of supplementary assays, to aid in the interpretation of the results, and sequencing of tumour DNA, for identification of somatic mutations, is encouraged. In addition, the study group launches an initiative to develop a gene-centric curated database of PPGL variants, with annual re-evaluation of variants of unknown significance by an expert group for purposes of reclassification and clinical guidance.

Paragangliomas of the Head and Neck: An Overview from Diagnosis to Genetics

Paragangliomas (PGL) develop from the parasympathetic system in the head and neck (HN) and arise primarily in four distinct areas: Carotid body, vagal, middle ear, and larynx. Globally, the diagnosis and morphologic features are the same regardless of anatomic site, however the incidence, frequency of genetic alterations/syndromes and differential diagnosis vary. It is now recognized that nearly 40% of all HN PGLs are hereditary, including a significant subset without a known family history. Now pathologists are central to the evaluation for diagnosis and further management of patients with HNPGLs. Specifically, SDHB immunohistochemical evaluation is an excellent screening tool to detect tumors with alterations in the SDH family of genes that represent the majority of hereditary cases in HNPGL. Similarly, SDHB immunohistochemical analysis allows for screening of PGL syndrome associated tumors (gastrointestinal stromal tumor (GIST), renal cell carcinoma (RCC), and pituitary adenomas) that have now been linked by their overlapping gene alterations. Awareness of the spectrum of these syndromes, and their associated tumors, positions the pathologist to augment patient care and surveillance.

Update from the 4th Edition of the World Health Organization Classification of Head and Neck Tumours: Paragangliomas

Updated editions of The World Health Organization Classification of Tumours Pathology & Genetics for both Head and Neck Tumours and Tumours of Endocrine Organs took place in 2016 based on consensus conferences. These editions present unification of concepts in paragangliomas and highlight expanding knowledge of their etiology. There is a major emphasis in the new bluebooks on familial/syndromic paragangliomas, representing ~40% of all head and neck paragangliomas. Ancillary use of immunohistochemical evaluation, specifically of SDHB, allows the pathologist to screen for a large subset of these potentially hereditary cases. In addition, similarly to other neuroendocrine tumors, paragangliomas are now considered to represent a continuum of risk, and are assessed in terms of risk stratification. Tumors with SDHB mutations pose the highest risk for metastasis. There is currently no validated or endorsed histologic grading system. Paragangliomas remain tumors of undetermined biologic potential and should not be termed benign.

Outcomes of annual surveillance imaging in an adult and paediatric cohort of succinate dehydrogenase B mutation carriers

OBJECTIVE

For 'asymptomatic carriers' of the succinate dehydrogenase subunit B (SDHB) gene mutations, there is currently no consensus as to the appropriate modality or frequency of surveillance imaging. We present the results of a surveillance programme of SDHB mutation carriers.

DESIGN

Review of clinical outcomes of a surveillance regimen in patients identified to have an SDHB gene mutation, based on annual MRI, in a single UK tertiary referral centre.

PATIENTS

A total of 92 patients were identified with an SDHB gene mutation. a total of 27 index patients presented with symptoms, and 65 patients were identified as asymptomatic carriers.

MEASUREMENTS

Annual MRI of the abdomen, with alternate year MRI of the neck, thorax and pelvis. Presence of an SDHB-related tumour included paraganglioma (PGL), phaeochromocytoma (PCC), renal cell carcinoma (RCC) and gastrointestinal stromal tumour (GIST).

RESULTS

A total of 43 PGLs, eight PCCs and one RCC occurred in the 27 index patients (23 solitary, four synchronous, five metachronous). A further 15 SDHB-related tumours (11 PGLs, three RCCs, one GIST) were identified in the asymptomatic carriers on surveillance screening (25% of screened carriers): 10 on the first surveillance imaging and five on subsequent imaging 2-6 years later. A total of 11 patients had malignant disease.

CONCLUSIONS

SDHB-related tumours are picked up as early as 2 years after initial negative surveillance scan. We believe the high malignancy rate and early identification rate of tumours justifies the use of 1-2 yearly imaging protocols and MRI-based imaging could form the mainstay of surveillance in this patient group thereby minimizing radiation exposure.

Nasal paraganglioma: differential diagnosis from a radiologic and pathologic perspective

A 33-year-old Asian male presented with spontaneous nosebleeds and olfactory sense problems for the past several years. CT scan and MRI demonstrated a large soft tissue mass in the nasal cavity and paranasal sinus with avid and homogeneous contrast enhancement, focal osseous destruction and a non-enhancing cyst at the intracranial tumour–brain margin. After complete endonasal resection, histopathological examination revealed a paraganglioma. This case highlights the non-specific imaging features of a rare paraganglioma of the anterior skull base and the differential diagnosis from both radiological and pathological perspective.