Prevalence of SDHB, SDHC, and SDHD germline mutations in clinic patients with head and neck paragangliomas

Succinate dehydrogenase mutations in head and neck paragangliomas: A systematic review and meta-analysis of individual patients' data

BACKGROUND

Head and neck paragangliomas (HNPs) have been associated with gene mutations in the succinate dehydrogenase (SDH) complex, but the clinical significance remains unclear. We sought to explore the demographics, clinical characteristics, treatment methods, and outcomes of SDH-mutated HNPs.

METHODS

Databases were systematically searched. Pooled event ratio and relative 95% confidence intervals were calculated for dichotomous outcomes. Meta-regression was performed. Cochran's Q test and I2 test assessed heterogeneity. Funnel plot and Egger's regression test assessed publication bias.

RESULTS

Forty-two studies with 8849 patients were included. Meta-regression revealed a significant correlation between multifocality and SDHD mutations (0.03 ± 0.006, p < 0.0001) and between distant metastases and SDHB mutations (0.06 ± 0.023, p = 0.008). There was no correlation between sex, age, tumor size, or familial occurrences and SDH-related mutations.

CONCLUSION

Multifocality of HNPs correlates with the SDHD mutational subtype, and metastases correlate with the SDHB subtype. Knowledge of HNP phenotypes associated with SDH-related mutations has the potential to influence the management approach to such HNPs.

Comprehensive Investigation of Angiogenesis, PASS Score and Immunohistochemical Factors in Risk Assessment of Malignancy for Paraganglioma and Pheochromocytoma

A challenging task in routine practice is finding the distinction between benign and malignant paragangliomas and pheochromocytomas. The aim of this study is to conduct a comparative analysis of angiogenesis by assessing intratumoral microvascular density (MVD) with immunohistochemical (IHC) markers (CD31, CD34, CD105, ERG), and S100 immunoreactivity, Ki67 proliferative index, succinate dehydrogenase B (SDHB) expressiveness, tumor size with one the most utilized score Pheochromocytoma of Adrenal Gland Scales Score (PASS), using tissue microarray (TMA) with 115 tumor samples, 61 benign (PASS < 4) and 54 potentially malignant (PASS ≥ 4). We found no notable difference between intratumoral MVD and potentially malignant behavior. The group of potentially malignant tumors is significantly larger in size, has lower intratumoral MVD, and a decreased number of S100 labeled sustentacular cells. Both groups have low proliferative activity (mean Ki67 is 1.02 and 1.22, respectively). Most tumors maintain SDHB expression, only 6 cases (5.2%) showed a loss of expression (4 of them in PASS < 4 group and 2 in PASS ≥ 4). PASS score is easily available for assessment and complemented with markers of biological behavior to complete the risk stratification algorithm. Size is directly related to PASS score and malignancy. Intratumoral MVD is extensively developed but it is not crucial in evaluating the malignant potential.

High incidence of occult familial SDHD cases amongst Czech patients with head and neck paragangliomas

Introduction

Head and neck paragangliomas (HNPGLs) are rare neuroendocrine tumors, which are mostly benign in nature. Amongst all genes, Succinate Dehydrogenase Subunit D (SDHD) is the most commonly mutated in familial HNPGLs. In about 30% of HNPGLs, germline mutations in SDHD can also occur in the absence of positive family history, thus giving rise to "occult familial" cases. Our aim was to evaluate the pattern of SDHD germline mutations in Czech patients with HNPGLs.

Materials and methods

We analyzed a total of 105 patients with HNPGLs from the Otorhinolaryngology departments of 2 tertiary centers between 2006 - 2021. All underwent complex diagnostic work-up and were also consented for genetic analysis.

Results

Eighty patients aged 13-76 years were included; around 60% with multiple PGLs were males. Carotid body tumor was the most frequently diagnosed tumor. Germline SDHD mutation was found in only 12% of the Czech patients; approximately 78% of those harboring the mutation had negative family history. The mutation traits had higher affiliation for multiple tumors with nearly 70% patients of ≤ 40 years of age.

Conclusion

An SDHD mutation variant was shared amongst unrelated patients but no founder-effect was established. Our findings confirmed that the pattern of SDHD mutation distribution amongst HNPGLs in Czech Republic differs from most studies worldwide.

Research progress on the pathogenesis of the SDHB mutation and related diseases

With the improvement of genetic testing technology in diseases in recent years, researchers have a more detailed and clear understanding of the source of cancers. Succinate dehydrogenase B (SDHB), a mitochondrial gene, is related to the metabolic activities of cells and tissues throughout the body. The mutations of SDHB have been found in pheochromocytoma, paraganglioma and other cancers, and is proved to affect the occurrence and progress of those cancers due to the important structural functions. The importance of SDHB is attracting more and more attention of researchers, however, reviews on the structure and function of SDHB, as well as on the mechanism of its carcinogenesis is inadequate. This paper reviews the relationship between SDHB mutations and related cancers, discusses the molecular mechanism of SDHB mutations that may lead to tumor formation, analyzes the mutation spectrum, structural domains, and penetrance of SDHB and sorts out some of the previously discovered diseases. For the patients with SDHB mutation, it is recommended that people in SDHB mutation families undergo regular genetic testing or SDHB immunohistochemistry (IHC). The purpose of this paper is hopefully to provide some reference and help for follow-up researches on SDHB.

Multi-Disciplinary Approach to Skull Base Paragangliomas

The treatment of skull base paragangliomas has moved towards the use of cranial nerve preservation strategies, using radiation therapy and subtotal resection in instances when aiming for gross total resection would be expected to cause increased morbidity compared to the natural history of the tumor itself. The goal of this study was to analyze the role of surgery in patients with skull base paragangliomas treated with CyberKnife stereotactic radiosurgery (SRS) for definitive tumor control. A retrospective review identified 22 patients (median age 65.5 years, 50% female) treated with SRS from 2010-2022. Fourteen patients (63.6%) underwent microsurgical resection. Gross total resection was performed in four patients for tympanic paraganglioma (n = 2), contralateral paraganglioma (n = 1), and intracranial tumor with multiple cranial neuropathies (n = 1). Partial/subtotal resection was performed for the treatment of pulsatile tinnitus and conductive hearing loss (n = 6), chronic otitis and otorrhea (n = 2), intracranial extension (n = 1), or episodic vertigo due to perilymphatic fistula (n = 1). Eighteen patients had clinical and imaging follow-up for a mean (SD) of 4.5 (3.4) years after SRS, with all patients having clinical and radiological tumor control and no mortalities. Surgery remains an important component in the multidisciplinary treatment of skull base paraganglioma when considering other outcomes besides local tumor control.

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.

Pyruvate transamination and NAD biosynthesis enable proliferation of succinate dehydrogenase-deficient cells by supporting aerobic glycolysis

Succinate dehydrogenase (SDH) is the mitochondrial enzyme converting succinate to fumarate in the tricarboxylic acid (TCA) cycle. SDH acts as a tumor suppressor with germline loss-of-function mutations in its encoding genes predisposing to aggressive familial neuroendocrine and renal cancer syndromes. Lack of SDH activity disrupts the TCA cycle, imposes Warburg-like bioenergetic features, and commits cells to rely on pyruvate carboxylation for anabolic needs. However, the spectrum of metabolic adaptations enabling SDH-deficient tumors to cope with a dysfunctional TCA cycle remains largely unresolved. By using previously characterized Sdhb-deleted kidney mouse cells, here we found that SDH deficiency commits cells to rely on mitochondrial glutamate-pyruvate transaminase (GPT2) activity for proliferation. We showed that GPT2-dependent alanine biosynthesis is crucial to sustain reductive carboxylation of glutamine, thereby circumventing the TCA cycle truncation determined by SDH loss. By driving the reductive TCA cycle anaplerosis, GPT2 activity fuels a metabolic circuit maintaining a favorable intracellular NAD+ pool to enable glycolysis, thus meeting the energetic demands of SDH-deficient cells. As a metabolic syllogism, SDH deficiency confers sensitivity to NAD+ depletion achieved by pharmacological inhibition of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of the NAD+ salvage pathway. Beyond identifying an epistatic functional relationship between two metabolic genes in the control of SDH-deficient cell fitness, this study disclosed a metabolic strategy to increase the sensitivity of tumors to interventions limiting NAD availability.

Paraganglioma of the Head and Neck: A Review

OBJECTIVE

To review the epidemiology, presentation, diagnosis, and management of head and neck paragangliomas.

METHODS

A literature review of english language papers with focus on most current literature.

RESULTS

Paragangliomas (PGLs) are a group of neuroendocrine tumors that arise in the parasympathetic or sympathetic ganglia. Head and neck PGLs (HNPGLs) comprise 65% to 70% of all PGLs and account for 0.6% of all head and neck cancers. The majority of HNPGLs are benign, and 6% to 19% of all HNPGLs develop metastasis outside the tumor site and significantly compromise survival. PGLs can have a familial etiology with germline sequence variations in different susceptibility genes, with the gene encoding succinate dehydrogenase being the most common sequence variation, or they can arise from somatic sequence variations or fusion genes. Workup includes biochemical testing to rule out secretory components, although it is rare in HNPGLs. In addition, imaging modalities, such as computed tomography and magnetic resonance imaging, help in monitoring in surgical planning. Functional imaging with DOTATATE-positron emission tomography, 18F-fluorodeoxyglucose, or 18F-fluorohydroxyphenylalanine may be necessary to rule out sites of metastases. The management of HNPGLs is complex depending on pathology, location, and aggressiveness of the tumor. Treatment ranges from observation to resection to systemic treatment. Similarly, the prognosis ranges from a normal life expectancy to a 5-year survival of 11.8% in patients with distant metastasis.

CONCLUSION

Our review is a comprehensive summary of the incidence, mortality, pathogenesis, presentation, workup and management of HNPGLs.

Application of the shear wave elastography in the assessment of carotid body tumors: A preliminary study

Objectives

To evaluate the elasticity of carotid body tumors (CBTs) by two-dimensional shear wave elastography (SWE).

Methods

22 pathologically or clinically confirmed CBTs in 16 patients were scanned by SWE. The maximum elasticity value (Emax) and its standard deviation (SDmax) in kPa and m/s for CBTs were obtained by placing a round ROI (2-3 mm) on the stiffest region of the CBTs. Elasticity value was compared between hard and soft groups at manual palpation, benign and malignant groups and among three Shamblin types. The area under the receiver operating characteristic curve (AUC) analysis was performed to evaluate the performance of SWE in the malignancy prediction of CBTs. Sensitivity, specificity and accuracy were calculated. The cut-off value was obtained by using the Youden index.

Results

There were 19 benign CBTs and 3 malignant CBTs. Emax (kPa and m/s) and SDmax (kPa) were significantly higher in the hard group than in the soft group at manual palpation (P<0.05); The distribution of Emax in kPa and m/s and SDmax in kPa were different in the three Shamblin types (P<0.05), Emax (kPa and m/s)increased from shambling I to Shambling II and Shambling III; Emax (kPa and m/s) were significantly higher in the malignant CBTs than in the benign ones (P<0.05). Emax in kPa and m/s had the similar AUC value (AUC=0.947, P=1.0000) for the prediction of malignant CBTs. Emax in kPa with the cut-off 124.9kPa showed a sensitivity of 100.0%, specificity of 94.7%, and an accuracy of 95.5% (Z=8.500, P<0.0001); Emax in m/s with the cut-off 5.9m/s showed a sensitivity of 100.0%, specificity of 89.5% and an accuracy of 90.9% for the prediction of malignant CBTs (Z=9.143, P<0.0001).

Conclusions

Quantitative analysis of SWE obtained the good performance in the elasticity assessment of CBTs.

Clinical presentation and diagnostic evaluation of pheochromocytoma: case series and literature review

BACKGROUND

Pheochromocytoma is a rare tumor frequently overlooked mainly due to the wide range of its clinical presentation, which may vary from entirely untypical signs and symptoms to life-threatening complications.

METHODS

The present study aims to present a case series recently treated in our center, with emphasis placed on patients' specific characteristics, clinical presentation and diagnostic evaluation. Relevant literature and current guidelines are being briefly reviewed to summarize screening for pheochromocytoma and appropriate diagnostic procedures.

RESULTS

While the classic symptoms include headache, palpitations and sweating with permanent or paroxysmal hypertension, a wide range of clinical manifestations may be attributed to pheochromocytoma. The initial screening test is measurement of plasma or 24-hour urine metanephrine levels. Abdominal computerized tomography with intravenous contrast infusion is suggested as the imaging examination of choice, whereas magnetic resonance imaging should be preferred over CT in exceptional cases. 123I-metaiodobenzylguanidine scintigraphy is particularly useful for establishing the diagnosis of pheochromocytoma and should be further applied to detect or exclude possible metastatic lesions.

CONCLUSION

Early diagnosis of pheochromocytoma is of great significance not only because it represents a curable form of secondary hypertension, but also because it is often related to familial syndromes, malignancy or metastatic disease. Physicians need to be familiar with relevant clinical manifestations and diagnostic steps to raise clinical suspiction of pheochromocytoma and establish a timely diagnosis.

A Case for Genetic Testing in Isolated Tympanic Paragangliomas

OBJECTIVE

The aim of this study is to describe two clinical cases, which we believe highlight the need to consider routine genetic testing of all patients with new diagnosis of a tympanic paraganglioma (PGL).

PATIENTS

Two patients seen in the ENT clinic at a tertiary center with a diagnosis of isolated tympanic PGL, without family history.

INTERVENTION

Since 2016, all patients with newly diagnosed isolated tympanic PGL (glomus tympanicum) are offered review by the clinical genetic team and genetic testing of a panel of paraganglioma/phaeochromocytoma predisposition genes. Previously only those with multiple PGL or a family history were tested.

MAIN OUTCOME MEASURES

We describe the results of genetic testing, the clinical course and discuss the ongoing implications for management.

RESULTS

Both cases were identified to have a pathogenic variant in the SDHB gene after initial surgery. The clinical course for both cases was complicated by disease recurrence, as well as metastatic and secretory disease in one case. Knowledge of genetic status has influenced ongoing management, with annual MRI surveillance for other SDH-related tumors.

CONCLUSION

These two cases reinforce the importance of offering genetic testing for all cases of isolated tympanic PGL. The discovery of a significant underlying genetic variant may affect management decisions and subsequent follow-up.

Giant carotid chemodectoma treated with a combination of surgery and CyberKnife radiotherapy: a case report and review of the literature

Background

Paragangliomas are rare vascular neuroendocrine tumors that develop in the extra-adrenal paraganglion tissue. They occur most commonly at the carotid bifurcation, where they are known as carotid body tumors. Most paragangliomas are benign, locally aggressive, infiltrative tumors. Approximately 10% of patients with paragangliomas develop distant metastases, 10% present with multiple or bilateral tumors (mostly carotid body tumors), and 10% have a family history of paragangliomas. The malignant transformation of carotid body tumors has been reported in 6% of cases.

Case presentation

We present the case of a 64 year-old Caucasian woman with a gigantic glomic tumor mass in the neck. Twenty years before the consultation, the patient had undergone an unsuccessful attempt to remove the mass. Over the last 3 years, the patient had felt enlargement of the mass at an increased rate, almost doubling the prior size. Angio magnetic resonance imaging showed a 9 cm paratracheal mass on the left cervical side that laterally displaced the sternocleidomastoid muscle and 2 c m of the trachea. Due to the change in the tumor behavior, the maxillofacial team at Ruber International Hospital decided to remove the tumor surgically after embolization. During the surgery the tumor was gently dissected from the carotid an removed from the carotid bifurcation uneventfully. Two small nodes adhering tightly to the internal carotid adventitia and the posterior torn hole were left in place to avoid any potentially life-threatening complications. The final biopsy confirmed the initial diagnosis of carotid body paraganglioma and showed a Ki-67 expression of 19%. Due to the aggressive growth behavior and high Ki-67 expression of the tumor, the patient was referred to the CyberKnife Unit of Ruber International Hospital for treatment of the remaining nodes.

Conclusions

The management of cervical paragangliomas is difficult and remains a challenge. Although the likelihood of tumor control is high with surgical or radiotherapeutic treatments, we currently lack consensus regarding the best treatment option. Nevertheless, in selected complex cases, such as the case we present, the combination of surgery and radiosurgery may allow complete local tumor control with minimal morbidity.

LncRNA expression and SDHB mutations in pheochromocytomas and paragangliomas

Although pheochromocytomas and paragangliomas (PPGLs) are usual low-grade neoplasms, the metastatic forms of these lesions are associated with high morbidity and mortality. Recent studies have discovered multiple aberrantly expressed long non-coding RNAs (lncRNAs) in cancers that may have regulatory roles in tumor pathogenesis and metastasis; however, the roles of some lncRNAs in PPGLs are still unknown. The expression levels of lncRNAs including metastasis-associated lung adenocarcinoma transcript (MALAT1), prostate cancer antigen 3 (PCA3), and HOX transcript antisense intergenic RNA (HOTAIR) in PPGLs were analyzed by in situ hybridization, using two tissue microarrays (TMAs). The pheochromocytoma (PCC) TMA consisted of normal adrenal medulla (N = 25), non-metastatic PCCs (N = 76) and metastatic PCCs (N = 5) while the paraganglioma (PGL) TMA had 73 non-metastatic PGLs and 5 metastatic PGLs. Immunohistochemical staining was performed on all samples with an anti-SDHB antibody. The correlations between lncRNA expression, loss of SDHB expression and clinical characteristics including tumor progression and disease prognosis were investigated. The expression levels of MALAT1 and PCA3 were significantly elevated (2.5-3.9 folds) in both non-metastatic and metastatic PCCs compared to normal adrenal medulla, although there were no significant differences between the non-metastatic and metastatic neoplasms. In contrast to non-metastatic PGLs, metastatic PGLs had significantly upregulated expression of MALAT1, PCA3, and HOTAIR. SDHB loss was more frequently observed in PGLs (25 of 78), especially in metastatic PGLs (5 of 5), compared to PCCs (2 of 81) and in 0 of 5 metastatic PCCs. Patients with SDHB loss, in contrast to SDHB retained, were younger at diagnosis, had higher rates of tumor recurrence, metastatic disease, and mortality. In addition, PGLs with SDHB loss had significantly increased expression of PCA3 compared to tumors with intact SDHB expression. Our findings suggest that specific lncRNAs may be involved in the SDHx signaling pathways in the tumorigenesis and in the development of PPGL.

Kidney cancer: from genes to therapy

Renal cell carcinoma incidence is rising worldwide with increasing subtype stratification by the World Health Organization. Each subtype has unique genetic alterations, cell biology changes and clinical findings. Such genetic alterations offer the potential for individualized therapeutic approaches that are rapidly progressing. This review highlights the most common subtypes of renal cell carcinoma, including both hereditary and sporadic forms, with a focus on genetic changes, clinical findings and ongoing clinical trials.

Genetic approaches to understand cellular responses to oxygen availability

Oxygen-sensing mechanisms have evolved to allow organisms to respond and adapt to oxygen availability. In metazoans, oxygen-sensing is predominantly mediated by the hypoxia inducible factors (HIFs). These transcription factors are stabilised when oxygen is limiting, activating genes involved in angiogenesis, cell growth, pH regulation and metabolism to reset cell function and adapt to the cellular environment. However, the recognition that other cellular pathways and enzymes can also respond to changes in oxygen abundance provides further complexity. Dissecting this interplay of oxygen-sensing mechanisms has been a key research goal. Here, we review how genetic approaches have contributed to our knowledge of oxygen-sensing pathways which to date have been predominantly focused on the HIF pathway. We discuss how genetic studies have advanced the field and outline the implications and limitations of such approaches for the development of therapies targeting oxygen-sensing mechanisms in human disease.

Genetic Variants in Patients with Multiple Head and Neck Paragangliomas: Dilemma in Management

Multiple head and neck paragangliomas (HNPGLs) are neuroendocrine tumors of a mostly benign nature that can be associated with a syndrome, precipitated by the presence of a germline mutation. Familial forms of the disease are usually seen with mutations of SDHx genes, especially the SDHD gene. SDHB mutations are predisposed to malignant tumors. We found 6 patients with multiple tumors amongst 30 patients with HNPGLs during the period of 2016 to 2021. We discuss the phenotypic and genetic patterns in our patients with multiple HNPGLs and explore the management possibilities related to the disease. Fifty percent of our patients had incidental findings of HNPGLs. Twenty-one biochemically silent tumors were found. Four patients had germline mutations, and only one had a positive family history. Three out of five underwent surgery without permanent complications. Preventative measures (genetic counselling and tumor surveillance) represent the gold standard in effectively controlling the disease in index patients and their relatives. In terms of treatment, apart from surgical and radiotherapeutic interventions, new therapeutic measures such as gene targeted therapy have contributed very sparsely. With the lack of standardized protocols, management of patients with multiple HNPGLs still remains very challenging, especially in those with sporadic or malignant forms of the disease.

Glutamine Metabolism in Cancer

Metabolism is a fundamental process for all cellular functions. For decades, there has been growing evidence of a relationship between metabolism and malignant cell proliferation. Unlike normal differentiated cells, cancer cells have reprogrammed metabolism in order to fulfill their energy requirements. These cells display crucial modifications in many metabolic pathways, such as glycolysis and glutaminolysis, which include the tricarboxylic acid (TCA) cycle, the electron transport chain (ETC), and the pentose phosphate pathway (PPP) [1]. Since the discovery of the Warburg effect, it has been shown that the metabolism of cancer cells plays a critical role in cancer survival and growth. More recent research suggests that the involvement of glutamine in cancer metabolism is more significant than previously thought. Glutamine, a nonessential amino acid with both amine and amide functional groups, is the most abundant amino acid circulating in the bloodstream [2]. This chapter discusses the characteristic features of glutamine metabolism in cancers and the therapeutic options to target glutamine metabolism for cancer treatment.

Head and neck paragangliomas in Norway, importance of genetics, updated diagnostic workup and treatment

BACKGROUND

Head and neck paragangliomas (HNPG) are rare and predominantly benign tumours, originating from the neuroendocrine paraganglionic system. A considerable proportion of HNPGs are hereditary, depending on the population.

AIMS/OBJECTIVES

The purpose of this study was to estimate the rate of hereditary HNPGs in a Scandinavian (Norwegian) population, report long-term experience with HNPGs and offer all patients diagnosed an updated follow-up, with emphasis on identifying hereditary HNPGs through genetic screening and multifocality by 18 F-2-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT).

MATERIAL AND METHODS

Our study was a partly retrospective and partly prospective cohort study. It included patients with HNPG diagnosed at Oslo University Hospital (OUH), Rikshospitalet between 1990 and 2017. The patients underwent genetic testing, ¹⁸F-FDG PET/CT and measurement of catecholamines and meta-nephrines in the plasma. All resection specimens and biopsies were subjected to histopathological review. The genetic testing protocol consisted of testing for mutations in the following genes; SDHD, SDHB, SDHC, VHL and RET.

RESULTS

Sixty-three patients were included in the study with a median age of 49 years (range 12 - 80). Cranial nerve dysfunction was present upon diagnosis in 13%, and 14% had multifocal paraganglioma (PG) disease. Fifty-six patients (89% of all the patients) underwent genetic testing, and 29% of these had a PG related mutation. Seven of the eight patients (88%) with multifocal PGs who underwent genetic testing had a mutation. In two of the patients, the ¹⁸F-FDG PET/CT revealed unknown and subclinical multifocality.

CONCLUSIONS AND SIGNIFICANCE

This is the first study with systematic genetic workup and PET/CT imaging in Scandinavia of HNPG patients. The mutation rate was within the lower range reported in the literature with respect to HNPGs. Combining genetic testing and PET/CT imaging in the diagnostic workup of HNPGs is valuable.

From Diagnosis to Therapy-PET Imaging for Pheochromocytomas and Paragangliomas

PURPOSE OF REVIEW

Pheochromocytoma and paraganglioma (PPGLs) are neuroendocrine tumors with diverse clinical presentations. PPGLs can be sporadic but often are associated with various syndromes, which can have variable clinical presentations. A thorough workup is therefore critical for staging, treatment, and follow-up. Imaging is an essential part of the workup and diagnosis of PPGLs.

RECENT FINDINGS

Improvements in cross-sectional imaging with radionuclides have increased specificity and sensitivity for identifying and treating PPGLs. Furthermore, a variety of targets on PPGLs has allowed for optimal imaging with radionuclides that can be used for staging and treatment. Currently, radionuclides are being evaluated for staging and treatment of PPGLs. Developing novel radionuclides that can identify disease sites and target them simultaneously provides a potential for improving survival and outcomes in patients with PPGLs. Given the clinical diversity among PPGLs, expanding the therapeutic arsenal against locally advanced or metastatic PPGLs can allow clinicians to evaluate and treat PPGLs thoroughly.

Carney Triad, Carney-Stratakis Syndrome, 3PAS and Other Tumors Due to SDH Deficiency

Succinate dehydrogenase (SDH) is a key respiratory enzyme that links Krebs cycle and electron transport chain and is comprised of four subunits SDHA, SDHB, SDHC and SDHD. All SDH-deficient tumors are caused by or secondary to loss of SDH activity. As many as half of the familial cases of paragangliomas (PGLs) and pheochromocytomas (PHEOs) are due to mutations of the SDHx subunits. Gastrointestinal stromal tumors (GISTs) associated with SDH deficiency are negative for KIT/PDGFRA mutations and present with distinctive clinical features such as early onset (usually childhood or adolescence) and almost exclusively gastric location. SDH-deficient GISTs may be part of distinct clinical syndromes, Carney-Stratakis syndrome (CSS) or dyad and Carney triad (CT). CSS is also known as the dyad of GIST and PGL; it affects both genders equally and is inherited in an autosomal dominant manner with incomplete penetrance. CT is a very rare disease; PGL, GIST and pulmonary chondromas constitute CT which shows female predilection and may be a mosaic disorder. Even though there is some overlap between CT and CSS, as both are due to SDH deficiency, CSS is caused by inactivating germline mutations in genes encoding for the SDH subunits, while CT is mostly caused by a specific pattern of methylation of the SDHC gene and may be due to germline mosaicism of the responsible genetic defect.

The versatile biochemistry of iron in macrophage effector functions

Macrophages are mononuclear phagocytes with remarkable polarization ability that allow them to have tissue-specific functions during development, homeostasis, inflammatory and infectious disease. One particular trophic factor in the tissue environment is iron, which is intimately linked to macrophage effector functions. Macrophages have a well-described role in the control of systemic iron levels, but their activation state is also depending on iron-containing proteins/enzymes. Haemoproteins, dioxygenases and iron-sulphur (Fe-S) enzymes are iron-binding proteins that have bactericidal, metabolic and epigenetic-related functions, essential to shape the context-dependent macrophage polarization. In this review, I describe mainly pro-inflammatory macrophage polarization focussing on the role of iron biochemistry in selected haemoproteins and Fe-S enzymes. I show how iron, as part of haem or Fe-S clusters, participates in the cellular control of pro-inflammatory redox reactions in parallel with its role as enzymatic cofactor. I highlight a possible coordinated regulation of haemoproteins and Fe-S enzymes during classical macrophage activation. Finally, I describe tryptophan and α-ketoglutarate metabolism as two essential effector pathways in macrophages that use diverse iron biochemistry at different enzymatic steps. Through these pathways, I show how iron participates in the regulation of essential metabolites that shape macrophage function.

Mutation profiling in eight cases of vagal paragangliomas

Background

Vagal paragangliomas (VPGLs) belong to a group of rare head and neck neuroendocrine tumors. VPGLs arise from the vagus nerve and are less common than carotid paragangliomas. Both diagnostics and therapy of the tumors raise significant challenges. Besides, the genetic and molecular mechanisms behind VPGL pathogenesis are poorly understood.

Methods

The collection of VPGLs obtained from 8 patients of Russian population was used in the study. Exome library preparation and high-throughput sequencing of VPGLs were performed using an Illumina technology.

Results

Based on exome analysis, we identified pathogenic/likely pathogenic variants of the SDHx genes, frequently mutated in paragangliomas/pheochromocytomas. SDHB variants were found in three patients, whereas SDHD was mutated in two cases. Moreover, likely pathogenic missense variants were also detected in SDHAF3 and SDHAF4 genes encoding for assembly factors for the succinate dehydrogenase (SDH) complex. In a patient, we found a novel variant of the IDH2 gene that was predicted as pathogenic by a series of algorithms used (such as SIFT, PolyPhen2, FATHMM, MutationTaster, and LRT). Additionally, pathogenic/likely pathogenic variants were determined for several genes, including novel genes and some genes previously reported as associated with different types of tumors.

Conclusions

Results indicate a high heterogeneity among VPGLs, however, it seems that driver events in most cases are associated with mutations in the SDHx genes and SDH assembly factor-coding genes that lead to disruptions in the SDH complex.

The Tricarboxylic Acid Cycle at the Crossroad Between Cancer and Immunity

Significance: The tricarboxylic acid (TCA) cycle is a housekeeping metabolic pathway essential for generation of energy and biosynthetic intermediates. Alterations of the TCA cycle play a pivotal role in oncogenesis and inflammation. As such, some metabolic vulnerabilities, imposed by TCA cycle dysfunction in cancer, have been identified. Similarly, the TCA cycle appeared as an actionable pathway in immunopathologies. Recent Advances: Metabolic changes accompanying cell transformation have been usually considered as adaptive mechanisms to malignant transformation. The identification of oncogenic mutations in some TCA cycle enzymes changed this view, indicating altered mitochondrial metabolism as an instrumental mechanism for cancer initiation. Similarly, the observation that TCA cycle-derived metabolites have multiple signaling roles in immune cells supports the idea of this pathway as a metabolic rheostat of immune responses. Critical Issues: This review summarizes the crucial role of the TCA cycle in pathophysiology describing the post-translational and epigenetic impact of oncometabolites accumulation in cancer and immune cells. Future Directions: Additional studies will be necessary to further explore the role of oncometabolites in paracrine signaling and to identify genuine metabolic and nutritional liabilities imposed by TCA cycle dysfunction in cancer, hardly to be escaped by resistance mechanisms.

Polymorphisms and rare variants identified by next-generation sequencing confer risk for lung cancer in han Chinese population

BACKGROUND

Lung cancer is one of the leading causes of cancer death worldwide, and genetic risk factors account for a large part of its carcinogenesis. The low economic requirements and high efficiency of next-generation sequencing (NGS) make it widely used in detecting genetic alterations in pathogenesis.

METHODS

We performed targeted panel sequencing in 780 Han Chinese lung cancer patients using a commercial probe, and the correlations between dozens of susceptible sites were verified in 1113 healthy controls. This study used Fisher's exact test and Benjamini-Hochberg FDR correction to analyze the mutual exclusion between mutated genes, and Pearson's p was used to verify the correlations between mutations and lung cancer susceptibility.

RESULTS

Our results determined the mutation spectrum and showed that each lung cancer patient carried at least one DNA mutation. The most frequently mutated gene was BRCA2 (mutation rate,10.6 %.). The co-occurrence and mutual exclusion analysis of DNA damage related genes showed that gene ATM was mutually exclusive from MSH6. We conducted a further case-control study in different subtypes of lung cancer and the results described 14 mutations associated with adenocarcinoma, 9 with squamous cell carcinoma, and 4 with small cell lung cancer. These variants were novel de-novo germline mutations in lung cancer. Particularly, rs3864017 in FANCD2 showed a protective effect of lung adenocarcinoma for carriers (OR = 0.146, 95 % CI = 0.052∼0.405, P_adjusted = 3.37 × 10^-4).

CONCLUSIONS

18 candidate mutations might alter the risk of lung cancer in the Han Chinese population, including polymorphisms rs3864017(FANCD2), rs55740729(MSH6) and 16 rare variants. The underlying mechanisms of candidate genes in lung cancer remain unclear and we suggest more functional studies on exploring how these genes affect the risk of lung cancer.

Clinical characteristics and outcomes of SDHB-related pheochromocytoma and paraganglioma in children and adolescents

PURPOSE

Pheochromocytomas/paragangliomas (PHEOs/PGLs) are rare in children with only a few SDHB mutation-related cases. Previous studies on children were conducted in small cohorts. This large set of pediatric patients provides robust data in the evaluation of clinical outcomes.

METHODS

Sixty-four pediatric PHEO/PGL patients with SDHB germline mutations were included in the present study. The clinical presentation, disease course, and survival rate were evaluated.

RESULTS

Thirty-eight males and 26 females were diagnosed with PHEO/PGL at a median age of 13 years. The majority of patients displayed norepinephrine hypersecretion and 73.44% initially presented with a solitary tumor. Metastases developed in 70% of patients at the median age of 16 years and were mostly diagnosed first 2 years and in years 12-18 post-diagnosis. The presence of metastases at the time of diagnosis had a strong negative impact on survival in males but not in females. The estimated 5-, 10-, and 20-year survival rates were 100%, 97.14%, and 77.71%, respectively.

CONCLUSION

The present report has highlighted several important aspects in the management of pediatric patients with SDHB mutations associated-PHEO/PGL. Initial diagnostic evaluation of SDHB mutation carriers should be started at age of 5-6 years with initial work-up focusing on abdominal region. Thorough follow-up is crucial first 2 years post-diagnosis and more frequent follow-ups are needed in years 10-20 post-diagnosis due to the increased risk of metastases. Although this age group developed metastasis as early as 5 years from diagnosis, we have shown that the overall 20-year prognosis and survival are good.

Tumor-specific prognosis of mutation-positive patients with head and neck paragangliomas

BACKGROUND

Genetic testing to identify succinate dehydrogenase (SDH) mutations in patients with head and neck paraganglioma (HNP) has been in clinical practice for more than a decade. However, the recurrence and metachronous tumor occurrence risks in surgically treated mutation-positive patients are not well studied.

METHODS

Clinical and procedural details of consecutive patients who underwent excision for HNP from January 1996 to October 2016 were retrospectively reviewed. End points included recurrence, metachronous tumor detection, and mortality. Germline DNA was tested to identify mutations in SDHx genes. Patients were divided into three groups on the basis of genetic testing: group I, positive; group II, negative; and group III, unknown or offered but not tested.

RESULTS

HNP was diagnosed in 268 patients, 214 (147 female; mean age, 47 years) included in this study. Directed genetic testing was performed in 68; mutations were detected in SDH in 47 (69%), a majority SDHD. In group I, 47 patients had 64 procedures for 81 tumors (52 carotid body tumors [CBTs]); 17 (36%) were bilateral, 7 (15%) multiple, 3 (6%) functional, and 7 (15%) malignant. Residual tumor in 10 was significant in 2, managed by radiation therapy and reoperation. Local recurrence was detected in 12 patients (25%) at a median of 8 years; 11 metachronous mediastinal and retroperitoneal paragangliomas were detected in 8 (17%) at a median of 13 years. Systemic metastases occurred in five (10%). Six patients (13%) had more than one recurrence. In group II, 21 patients had 22 procedures for 23 tumors, 17 CBTs. Two (9%) were bilateral and two (9%) malignant. Excision was complete in all with no recurrence or systemic metastasis at last follow-up. For group III, 146 patients underwent 153 procedures for 156 tumors, 95 CBTs; 7 (5%) were bilateral, 2 (1%) multiple, 8 (5%) functional, and 1 (0.6%) malignant. Local recurrence was detected in nine (6%) at a median of 9 years and metachronous HNP in three (2%) at a median of 5 years. Systemic metastases occurred in two (1%). Mortality was 4% in group I and 3% in group III, none procedure or tumor related. Group I (mutation positive) had 10-year overall, recurrence-free, and metachronous tumor-free survival rates of 93%, 69.4%, and 73%, respectively, lower than the other groups (P < .001).

CONCLUSIONS

Bilateral, functional, malignant, recurrent, and metachronous tumors are more common in SDH mutation-positive patients with HNP. Overall survival in patients with HNP is high. Metachronous tumors or local recurrences occur late, and long-term follow-up is necessary.

Palliative Interventional Embolization for Finding of Ectopic Noradrenaline-Secreting Pheochromocytoma in the Nasal Cavity

A 52-year-old male who had chronic hypertension for several years presented with abrupt epistaxis. The CT scan revealed a 40 mm × 40 mm mass in the nasal cavity intended to the maxillary sinus and the base of skull. Nasal endoscope biopsy and serum/urinary catecholamine detection conformed an ectopic noradrenaline-secreting pheochromocytoma. The present research was to discuss the clinical characteristics of the rare pheochromocytoma and the palliative interventional embolization for it.

A PATIENT WITH AN ATYPIC NECK MASS LESION

An 81-year-old woman presented with a history of essential hypertension for eight years and an asymptomatic multinodular goiter that had been incidentally discovered on neck ultrasonography two years ago and an-isohypoechoic mass lesion located adjacent to the right lobe inferior pole of the thyroid gland. Parathyroid adenoma or lymphadenopathy were the differential diagnosis. After two years, the endocrine surgeon decided to operate her multinodular goiter and her probably benign lesion. Intraoperatively, the blood pressure and pulse rate increased markedly and intravenous antihypertensive treatment was administered. She was discharged after blood pressure control. A 2 mm micromedullary thyroid carcinoma with C-cell hyperplasia located on the left lobe of the thyroid was detected. The aforementioned mass lesion was also reported as typical cervical paraganglioma. Because of concomitant medullary thyroid carcinoma with C-cell hyperplasia and paraganglioma the patient was subjected to genetic counseling and molecular testing for hereditary cancer syndromes. A variation of the succinate dehydrogenase gene D (SDHD) NM_003002.3: c.325C> T (Gln109Term) has been reported as the disease-causing mutation. Herein we present a case diagnosed for neck paraganglioma and medullary thyroid carcinoma after an intraoperative hypertensive crisis.

Genetic and epigenetic differences of benign and malignant pheochromocytomas and paragangliomas (PPGLs)

Pheochromocytomas and paragangliomas (PPGLs) are tumors arising from the adrenal medulla and sympathetic/parasympathetic paraganglia, respectively. According to Th e Cancer Genome Atlas (TCGA), approximately 40% of PPGLs are due to germ line mutations in one of 16 susceptibility genes, and a further 30% are due to somatic alterations in at least seven main genes (VHL, EPAS1, CSDE1, MAX, HRAS, NF1, RET, and possibly KIF1B). Th e diagnosis of malignant PPGL was straight forward in most cases as it was defined as presence of PPGL in non-chromaffin tissues. Accordingly, there is an extreme need for new diagnostic marker(s) to identify tumors with malignant prospective. Th e aim of this study was to review all suggested genetic and epigenetic alterations that are remarkably different between benign and malignant PPGLs. It seems that more than two genetic mutation clusters in PPGLs and other genetic and methylation biomarkers could be targeted for malignancy discrimination in different studies.

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.

Level of plasma catecholamine predicts surgical outcomes of carotid body tumors: Retrospective cohort study

BACKGROUNDS

Carotid body tumors (CBTs) are rare neoplasms and some of them produce catecholamine. Although operations for catecholamine-producing CBTs are safe, the relationship between prognosis and endocrine function has not been analyzed before.

METHODS

Patients diagnosed with CBTs in our department between 2009 and 2018 were analyzed. Plasma catecholamine was examined as a variable of surgical outcomes and prognosis by using statistical methods.

RESULTS

Patients who suffered CBTs and underwent operations were divided into two groups according to their plasma catecholamine. Patients in the normal group had more or heavier surgical complications, such as neurological complications (P = .008) and blood loss (P = .03), than those in the high group. However, overall survival, local recurrence, and remote metastasis were not varied significantly in both groups.

CONCLUSIONS

A high level of plasma catecholamine was a predictor for the improved operative outcomes of CBTs. Hence, nonfunctional CBTs had further short-term surgical complications.

Thyroid Paraganglioma: Our Experience and Systematic Review of the Literature on a Rare Tumor

INTRODUCTION

Primary paraganglioma (PG) of the thyroid gland is an extremely rare neuroendocrine tumor with potential for misdiagnosis. We describe 2 cases of thyroid PG, suggest a possible diagnostic and therapeutic management strategy, and present a systematic review of the literature.

CASE REPORTS

Two 67-year-old women presented similarly with asymptomatic but rapidly growing thyroid nodules in which malignancy was suspected after fine needle aspiration biopsy, "THY 4" according to the 2014 SIAPEC classification, both undergoing total thyroidectomy. Unexpectedly, immunohistochemistry showed neuroendocrine cellular architecture that was negative for common markers of well-differentiated follicular neoplasms, thyroglobulin, thyroid transcription factor 1, cytokeratins and medullary thyroid cancer, calcitonin, carcinoembryonic antigen, whereas neuron-specific enolase, synaptophysin, chromogranin A, and S-100 protein were highly expressed, confirming the diagnosis of primary thyroid PG. The patients were both discharged on postoperative day 2, without any other therapy and are currently well without evidence of local recurrence of metastatic disease, after 4 years and 3 months of follow-up, respectively.

DISCUSSION

These are the only 2 cases of thyroid PG experienced in our center which specializes in thyroid surgery. Thyroid PG is a rare neuroendocrine neoplasm first described by Van Miert in 1964 with just over 50 cases reported in the literature. Our experience is concordant with the literature that the diagnosis of the primary PG of the thyroid is challenging, due to its low prevalence and the cytologic and histopathologic similarities with other more frequently diagnosed benign and malignant thyroid tumors. Immunohistochemistry is required for definitive diagnosis but gross tumor characteristics are also helpful for diagnosis. Surgical resection is the recommended standard treatment.

18F-FDOPA PET/CT Combined with MRI for Gross Tumor Volume Delineation in Patients with Skull Base Paraganglioma

In this simulation study, we assessed differences in gross tumor volume (GTV) in a series of skull base paragangliomas (SBPGLs) using magnetic resonance imaging (MRI), ¹⁸F-dihydroxyphenylalanine (¹⁸F-FDOPA) combined positron emission tomography/computed tomography (PET/CT), and ¹⁸F-FDOPA PET/MRI images obtained by rigid alignment of PET and MRI. GTV was delineated in 16 patients with SBPGLs on MRI (GTV_MRI), ¹⁸F-FDOPA PET/CT (GTV_PET), and combined PET/MRI (GTV_PET/MRI). GTV_PET/MRI was the union of GTV_MRI and GTV_PET after visual adjustment. Three observers delineated GTV_MRI and GTV_PET/MRI independently. Excellent interobserver reproducibility was found for both GTV_MRI and GTV_PET/MRI. GTV_PET and GTV_MRI were not significantly different. However, there was some spatial difference between the locations of GTV_MRI, GTV_PET, and GTV_PET/MRI. The Dice similarity coefficient median value was 0.4 between PET/CT and MRI, and 0.8 between MRI and PET/MRI. The combined use of PET/MRI produced a larger GTV than MRI alone. Nevertheless, both the target-delivered dose and organs-at-risk conservancy were respected when treatment was planned on the PET/MRI-matched data set. Future integration of ¹⁸F-FDOPA PET/CT into clinical practice will be necessary to evaluate the influence of this diagnostic modality on SBPGL therapeutic management. If the clinical utility of ¹⁸F-FDOPA PET/CT and/or PET/MRI is confirmed, GTV_PET/MRI should be considered for tailored radiotherapy planning in patients with SBPGL.

Tumor multifocality with vagus nerve involvement as a phenotypic marker of SDHD mutation in patients with head and neck paragangliomas: A 18 F-FDOPA PET/CT study

BACKGROUND

¹⁸ F-FDOPA PET/CT was proved to be a highly sensitive imaging method for detecting head and neck paraganglioma (HNPGL). The primary aim of the study was to evaluate the relationship between tumor characteristics and the SDHx-mutational status in a large series of patients with HNPGL evaluated by ¹⁸ F-FDOPA PET/CT.

METHODS

A total of 104 patients with HNPGL (65 sporadic/39 SDHx-mutated) were included.

RESULTS

In comparison to SDHB/SDC/SDHx-negative cases, patients with SDHD were younger at diagnosis and had a higher rate of multifocal, vagal, and carotid paraganglioma. In patients with SDHD, vagal paraganglia represented the primary site of tumor origin. Multicentric involvement of the vagus nerve alone or in association with other locations was found to be a typical feature of SDHD cases compared to other cases (odds ratio = 59.4).

CONCLUSION

The present study shows that tumor multifocality within the vagus nerve is a phenotypic marker of SDHD mutation. This information is essential in the choice of the therapeutic strategy.

Long-Term Outcome Following Stereotactic Radiosurgery for Glomus Jugulare Tumors: A Single Institution Experience of 20 Years

BACKGROUND

Glomus jugulare tumors (GJTs) are rare benign tumors, which pose significant treatment challenges due to proximity to critical structures.

OBJECTIVE

To evaluate the long-term clinical and radiological outcome in patients undergoing stereotactic radiosurgery (SRS) for GJTs through retrospective study.

METHODS

Forty-two patients with 43 GJTs were treated using Gamma Knife radiosurgery (GKRS; Elekta AB, Stockholm, Sweden) at our institute from 1997 to 2016. Clinical, imaging, and radiosurgery data were collected from an institutional review board approved database.

RESULTS

Most patients were females (n = 35, 83.3%) and median age was 61 yr (range 23-88 yr). Median tumor volume and diameter were 5 cc and 3 cm, respectively, with a median follow-up of 62.3 mo (3.4-218.6 mo). Overall, 20 patients (47.6%) improved clinically and 14 (33.3%) remained unchanged at last follow-up. New onset or worsening of hearing loss was noted in 6 patients (17.2%) after SRS. The median prescription dose to the tumor margin was 15 Gy (12-18 Gy). Median reduction in tumor volume and maximum tumor diameter at last follow-up was 33.3% and 11.54%, respectively. The 5-yr and 10-yr tumor control rates were 87% ± 6% and 69% ± 13%, respectively. There was no correlation between maximum or mean dose to the internal acoustic canal and post-GK hearing loss (P > .05).

CONCLUSION

SRS is safe and effective in patients with GJTs and results in durable, long-term control. SRS has lower morbidity than that associated with surgical resection, particularly lower cranial nerve dysfunction, and can be a first-line management option in these patients.

The spectrum of SDHD mutations in Russian patients with head and neck paraganglioma

AIM OF THE STUDY

It was found that the mutations in the SDHD gene, encoding one of subunits of the succinate dehydrogenase complex, lead to the development of head and neck paraganglioma (HNPGL). We analyzed this gene in 91 patients with HNPGL from Russia.

MATERIALS AND METHODS

DNA was isolated from the whole blood. A screening for mutations was performed by Sanger sequencing.

RESULTS

We revealed three missense mutations that have been described previously: p.Pro81Leu, p.His102Arg, p.Tyr114Cys. Moreover, we identified a novel potentially pathogenic variant (p.Trp105*).

CONCLUSIONS

We found that mutations in the SDHD gene were less common in Russian patients compared with the majority of European populations. It was shown that the p.His102Arg mutation is a major mutation in Russia. We confirmed the previous suggestion that a bilateral localization of the tumor and the carotid type represent a marker of the genetically determined form of HNPGL.

Pulmonary and mediastinal paragangliomas: rare endothoracic malignancies with challenging diagnosis and treatment

Background

Pulmonary and mediastinal paragangliomas are rare tumors that may have neuroendocrine activity or be non-functional, incidental, in asymptomatic patients, or causing mass effect symptoms. Although being low-grade tumors, they can display an aggressive behaviour, developing local infiltration and distant metastases. We report our experience with three endothoracic paragangliomas and a Literature review, to point out diagnostic difficulties and problems related to surgical treatment.

Methods

From 2009 to 2017, we treated 3 patients with histological diagnosis of paraganglioma: 2 pulmonary, 1 mediastinal. No one presented catecholamine-secreting syndromes; pulmonary cases were asymptomatic, while the mediastinal one had aspecific cough and dyspnea. Imaging diagnosis was based on chest computerized tomography (CT) and magnetic resonance imaging (MRI) scan. No patient had preoperative histological diagnosis. Intraoperative pathological examination was suggestive for malignancy: in pulmonary cases, wedge resection and lobectomy were performed; the middle mediastinal mass was completely removed after challenging dissection, isolation and section of numerous vascular pedicles.

Results

Postoperative course was uneventful in all cases. No patient received adjuvant treatments. At a median follow-up of 47 months (range, 6-102 months), two patients are alive, without local or distant recurrence; one patient died 6 months after surgery, due to disease progression.

Conclusions

Endothoracic paragangliomas, rare and often asymptomatic tumors, are of difficult diagnosis and should be considered malignant tumors, due to the potential aggressive behaviour of cases with high mitotic index and the frequent possibility of recurrence and metastases. Surgical resection is the treatment of choice and careful intraoperative manipulation is recommended, due to the high vascularity of these tumors, to prevent complications. After complete excision, long-term prognosis is generally good. However, even after surgical removal, a close, periodical and life-long follow-up is mandatory.

Risk Stratification on Pheochromocytoma and Paraganglioma from Laboratory and Clinical Medicine

Pheochromocytoma (PCC) and sympathetic paraganglioma (PGL) are rare neuroendocrine tumors characterized by catecholamine production in the adrenal medulla and extra-adrenal paraganglia. PCC and PGL (PPGL) with metastasis was termed malignant PPGL. However, the distinction between “benign” and “malignant” PPGLs has been debated. Currently, all PPGLs are believed to have some metastatic potential and are assigned malignant tumors (ICD-O/3) by the WHO Classification of Endocrine Organs (2017, 4th edition). Therefore, the previous categories benign and malignant PPGL have been eliminated in favor of risk stratification approach. The Grading of Adrenal Pheochromocytoma and Paraganglioma (GAPP) is a tool for risk stratification for predicting metastasis and the prognosis of patients. At least 30% of PPGLs are hereditary, with 20 genes identified and genotype-phenotype correlations clarified. Of these genes, VHL, RET and NF1 have been well investigated and are the primary cause of bilateral PCC. In addition, mutation of succinate dehydrogenase gene subunits SDHB and SDHD are strongly correlated with extra-adrenal location, younger age, multiple tumors, metastasis and poor prognosis. Disease stratification by catecholamine phenotype and molecular profiling correlates with histological grading by GAPP. PPGLs should be understood comprehensively based on clinical, biochemical, molecular and pathological data for patient care. A flow chart for pathological diagnosis is included.

A Novel SDHB IVS2-2A>C Mutation Is Responsible for Hereditary Pheochromocytoma/Paraganglioma Syndrome

Pheochromocytomas and paragangliomas are neuroendocrine tumors which arise from adrenal medulla, and sympathetic or parasympathetic nerves, respectively. Hereditary cases afflicted by both or either pheochromocytomas and paragangliomas have been reported: these are called hereditary pheochromocytoma/paraganglioma syndromes (HPPS). Many cases of HPPS are caused by mutations of one of the succinate dehydrogenase (SDH) genes; mainly SDHB and SDHD that encode subunits for the mitochondrial respiratory chain complex II. In this study, we investigated mutations of SDH genes in six HPPS patients from four Japanese pedigrees using peripheral blood lymphocytes (from one patient with pheochromocytoma and five patients with neck paraganglioma) and tumor tissues (from two patients with paraganglioma). Results showed that all of these pedigrees harbor germline mutations in one of the SDH genes. In two pedigrees, a novel IVS2-2A>C mutation in SDHB, at the acceptor-site in intron 2, was found, and the tumor RNA of the patient clearly showed frameshift caused by exon skipping. Each of the remaining two pedigrees harbors a reported missense mutation, R242H in SDHB or G106D in SDHD. Importantly, all these mutations are heterozygous in constitutional DNAs, and two-hit mutations were evident in tumor DNAs. We thus conclude that the newly identified IVS2-2A>C mutation in SDHB is responsible for HPPS. The novel mutation revealed by our study may contribute to improvement of clinical management for patients with HPPS.

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.

Multifocal Paraganglioma and Pheochromocytoma Due to Truncated SDHD Mutation

OBJECTIVE

Pheochromocytoma and paraganglioma (PPGL) are rare autosomal dominant disorders derived from the neural crest chromaffin tissues of the autonomic nervous system. The succinate dehydrogenase complex subunit D (SDHD) gene has been implicated as one of the pathogenic genes. Although more than 100 SDHD mutations have been reported, the phenotype-genotype association remains unclear.

METHODS

We reported a case of a patient who presented with multifocal PPGLs and with a rare SDHD mutation, and reviewed the phenotype-genotype association of SDHD.

RESULTS

We identified a pathogenic variant of SDHD (c.170-1G>T, NM_003002.3), which caused the complete deletion of exon 3 in the transcript and resulted in a shorter and unstable SDHD mRNA. And truncated SDHD mutations were prone to cause multifocal PPGL, whereas missense SDHD mutations usually caused unifocal lesions.

CONCLUSION

This is the first report linking the c.170-1G>T variant to multifocal tumors. We recommend whole-body imaging examinations and close, regular follow-up for these patients, given the risk of multifocal tumor development.

Hereditary Paraganglioma Syndrome Associated with SDHD Gene Mutations: A Patient with Multicentric Presentation Treated with Radiotherapy. Case Report

Introduction

Extra-adrenal paragangliomas are rare tumors arising from neuroendocrine cells. Sporadic and hereditary forms have been recognized. Among the latter, the PGL1 and PGL4 syndromes are associated with a high risk of multiple localizations. The treatment of choice for paragangliomas is surgical resection, but in some cases surgery can be difficult due to particular or multiple tumor sites or may result in severe neurological deficits. In such cases radiotherapy can be an effective alternative. In this paper we describe the case of a patient affected by hereditary paraganglioma syndrome with multicentric presentation who was treated at our center by external radiotherapy.

Case report

A 55-year-old man presented in April 2008 with multiple paragangliomas: one in the left pontocerebellar angle, two in the middle neck, one mediastinal paraaortic mass, and an abdominal paraaortic lesion. The left pontocerebellar and mediastinal tumors were treated with three-dimensional conformal radiotherapy (3D-CRT) at total doses of 50.40 Gy and 55.80 Gy, respectively. The neck lesions were treated with intensity-modulated radiotherapy (IMRT) at a total dose of 55.80 Gy. The abdominal paraaortic lesion was surgically resected.

Results

No severe acute or late toxicity as evaluated with the EORTC-RTOG scale was observed. Fourteen months after the end of radiotherapy a whole body CT scan showed that the tumor lesions were stable in size and in their relations to contiguous structures. The arterial pressure was controlled by medical therapy and urine catecholamine levels were within the normal range.

Conclusions

We believe that in patients affected by unresectable paragangliomas radiotherapy is a safe and effective alternative to surgery. The use of high-dose conformity techniques such as 3D-CRT and IMRT will allow higher local control rates with relatively few side effects thanks to the possibility of dose escalation and reduction of the amount of irradiated healthy tissues.

Loss of maternal chromosome 11 is a signature event in SDHAF2, SDHD, and VHL-related paragangliomas, but less significant in SDHB-related paragangliomas

Germline mutations in the succinate dehydrogenase (SDHA, SDHB, SDHC, SDHD, SDHAF2) or Von Hippel-Lindau (VHL) genes cause hereditary paraganglioma/pheochromocytoma. While SDHB (1p36) and VHL (3p25) are associated with autosomal dominant disease, SDHD (11q23) and SDHAF2 (11q13) show a remarkable parent-of-origin effect whereby tumor formation is almost completely dependent on paternal transmission of the mutant allele. Loss of the entire maternal copy of chromosome 11 occurs frequently in SDHD-linked tumors, and has been suggested to be the basis for this typical inheritance pattern.Using fluorescent in situ hybridization, microsatellite marker and SNP array analysis, we demonstrate that loss of the entire copy of chromosome 11 is also frequent in SDHAF2-related PGLs, occurring in 89% of tumors. Analysis of two imprinted differentially methylated regions (DMR) in 11p15, H19-DMR and KvDMR, showed that this loss always affected the maternal copy of chromosome 11. Likewise, loss of maternal chromosome 11p15 was demonstrated in 85% of SDHD and 75% of VHL-related PGLs/PCCs. By contrast, both copies of chromosome 11 were found to be retained in 62% of SDHB-mutated PGLs/PCCs, while only 31% showed loss of maternal chromosome 11p15. Genome-wide copy number analysis revealed frequent loss of 1p in SDHB mutant tumors and show greater genomic instability compared to SDHD and SDHAF2.These results show that loss of the entire copy of maternal chromosome 11 is a highly specific and statistically significant event in SDHAF2, SDHD and VHL-related PGLs/PCCs, but is less significant in SDHB-mutated tumors, suggesting that these tumors have a distinct genetic etiology.

The emerging role and targetability of the TCA cycle in cancer metabolism

The tricarboxylic acid (TCA) cycle is a central route for oxidative phosphorylation in cells, and fulfills their bioenergetic, biosynthetic, and redox balance requirements. Despite early dogma that cancer cells bypass the TCA cycle and primarily utilize aerobic glycolysis, emerging evidence demonstrates that certain cancer cells, especially those with deregulated oncogene and tumor suppressor expression, rely heavily on the TCA cycle for energy production and macromolecule synthesis. As the field progresses, the importance of aberrant TCA cycle function in tumorigenesis and the potentials of applying small molecule inhibitors to perturb the enhanced cycle function for cancer treatment start to evolve. In this review, we summarize current knowledge about the fuels feeding the cycle, effects of oncogenes and tumor suppressors on fuel and cycle usage, common genetic alterations and deregulation of cycle enzymes, and potential therapeutic opportunities for targeting the TCA cycle in cancer cells. With the application of advanced technology and in vivo model organism studies, it is our hope that studies of this previously overlooked biochemical hub will provide fresh insights into cancer metabolism and tumorigenesis, subsequently revealing vulnerabilities for therapeutic interventions in various cancer types.

Metabologenomics of Phaeochromocytoma and Paraganglioma: An Integrated Approach for Personalised Biochemical and Genetic Testing

The tremendous advances over the past two decades in both clinical genetics and biochemical testing of chromaffin cell tumours have led to new considerations about how these aspects of laboratory medicine can be integrated to improve diagnosis and management of affected patients. With germline mutations in 15 genes now identified to be responsible for over a third of all cases of phaeochromocytomas and paragangliomas, these tumours are recognised to have one of the richest hereditary backgrounds among all neoplasms. Depending on the mutation, tumours show distinct differences in metabolic pathways that relate to or even directly impact clinical presentation. At the same time, there has been improved understanding about how catecholamines are synthesised, stored, secreted and metabolised by chromaffin cell tumours. Although the tumours may not always secrete catecholamines it has become clear that almost all continuously produce and metabolise catecholamines. This has not only fuelled changes in laboratory medicine, but has also assisted in recognition of genotype-biochemical phenotype relationships important for diagnostics and clinical care. In particular, differences in catecholamine and energy pathway metabolomes can guide genetic testing, assist with test interpretation and provide predictions about the nature, behaviour and imaging characteristics of the tumours. Conversely, results of genetic testing are important for guiding how routine biochemical testing should be employed and interpreted in surveillance programmes for at-risk patients. In these ways there are emerging needs for modern laboratory medicine to seamlessly integrate biochemical and genetic testing into the diagnosis and management of patients with chromaffin cell tumours.

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.