Genetic analysis in the diagnosis of familial paragangliomas

Research in the genetics of pheochromocytoma and paraganglioma: a bibliometric analysis from 2002 to 2022

Over the past two decades, there has been a significant growth in articles focusing on the genetics of pheochromocytoma and paraganglioma (PPGL). We used bibliometric methods to investigate the historical changes and trend in PPGL research. There was a total of 1263 articles published in English from 2002 to 2022 included in our study. The number of annual publications and citations in this field has been increasing in the past 20 years. Furthermore, most of the publications originated from the European countries and the United States. The co-occurrence analysis showed close cooperation between different countries, institutions, or authors. The dual-map discipline analysis revealed that majority articles focused on four disciplines: #2 (Medicine, Medical, Clinical), #4 (Molecular, Biology, Immunology), #5 (Health, Nursing, Medicine), and #8 (Molecular, Biology, Genetics). The hotspot analysis revealed the keywords that have been landmark for PPGL genetics research in different time periods, and there was continued interest in gene mutations, especially on SDHX family genes. In conclusion, this study displays the current status of research and future trends in the genetics of PPGL. In future, more in-depth research should concentrate on crucial mutation genes and their specific mechanisms to assist in molecular target therapy. It is hoped that this study may help to provide directions for future research on genes and PPGL.

Intraoperative Scintigraphy With Portable Gamma Camera for the Localization of Interaortocaval Paraganglioma

ABSTRACT

A 15-year-old adolescent girl diagnosed of interaortocaval paraganglioma with a positive 123I-MIGB SPECT/CT and 1 unsuccessful prior surgery was operated on with the assistance of a handheld gamma camera. Once the lesion was located and removed, 2 images were taken, one of the surgical field (without 123I-MIGB uptake) and another of the tumor ex vivo (with high 123I-MIGB uptake), confirming that the lesion had been satisfactorily excised. This case highlights the use of a portable gamma camera as a useful tool to locate this rare tumor, with a SPECT/CT positive for 123I-MIGB and a difficult anatomical location suspected.

FDG PET-CT imaging in head and neck paragangliomas: A centre experience

Head and neck paragangliomas (HNPGLs) are rare tumours with ~ 30% genetic mutations, mainly in succinate dehydrogenase (SDHx) genes. The utility of FDG PET-CT in HNPGLs is questioned by recent developments in novel radiotracers. We therefore performed a retrospective study in a single tertiary referral centre to address the utility of FDG PET/CT in HNPGLs.

METHODS

Clinical data on genetic testing and follow-up were collected for patients who had FDG PET-CT scans from 2004 to 2016. Receiver operator characteristic (ROC) analysis was used to compare standardized uptake values (SUVs), metabolic tumour volume (MTV) and total lesion glycolysis (TLG) between lesions in patients who had a clinically related event: event (+) and those who did not: event (-). Similarly, we compared PET parameters between SDHx+ patients and a control group with low probability of mutation.

RESULTS

Of 153 HNPGL patients, 73 (29 SDHx+) with 93 FDG-positive lesions were identified: 53.8% of lesions were assessed in a pre-therapeutic setting. In comparison with a reference extracted from clinicoradiological database, FDG PET-CT showed good performance to detect HNPGLs (96.6% accuracy). In this study population, 16 disease progression, 1 recurrence and 1 death were recorded and event (+) patients had lesions with higher SUVmax (p = .03 and p = .02, respectively). Conversely, there were no differences in PET parameters between lesions in SDHx+ patients and controls with low probability of SDHx+ mutations.

CONCLUSIONS

FDG PET-CT has clinical utility in HNPGLs, mostly before local treatment. There were no significant differences in PET parameters between SDHx patients and a sporadic HNPGL population. However, regardless of SDHx mutation status, a high SUVmax was associated with more clinical events and prompts to a closer follow-up.

Paragangliomas of the Head and Neck

Paragangliomas of the head and neck are rare vascular skull-base tumors derived from the paraganglionic system with an estimated incidence of 1:30,000 accounting for 3% of all paragangliomas. The most common paraganglioma locations of the head and neck in descending order are the carotid body, jugular, tympanic, and vagal paragangliomas. This article discusses the clinical characterics, normal anatamy, imaging findings and protocols, pathology, staging, and differential diagnosis for paragangliomas of the head and neck.

Connecting molecular pathways to hereditary cancer risk syndromes

An understanding of the genetic causes and molecular pathways of hereditary cancer syndromes has historically informed our knowledge and treatment of all types of cancers. For this review, we focus on three rare syndromes and their associated genetic mutations including BAP1, TP53, and SDHx (SDHA, SDHB, SDHC, SDHD, SDHAF2). BAP1 encodes an enzyme that catalyzes the removal of ubiquitin from protein substrates, and germline mutations of BAP1 cause a novel cancer syndrome characterized by high incidence of benign atypical melanocytic tumors, uveal melanomas, cutaneous melanomas, malignant mesotheliomas, and potentially other cancers. TP53 mutations cause Li-Fraumeni syndrome (LFS), a highly penetrant cancer syndrome associated with multiple tumors including but not limited to sarcomas, breast cancers, brain tumors, and adrenocortical carcinomas. Genomic modifiers for tumor risk and genotype-phenotype correlations in LFS are beginning to be identified. SDH is a mitochondrial enzyme complex involved in the tricarboxylic acid (TCA) cycle, and germline SDHx mutations lead to increased succinate with subsequent paragangliomas, pheochromocytomas, renal cell carcinomas (RCCs), gastrointestinal stromal tumors (GISTs), and other rarer cancers. In all of these syndromes, the molecular pathways have informed our understanding of tumor risk and successful early tumor surveillance and screening programs.

Stereotactic LINAC-Radiosurgery for Glomus Jugulare Tumors: A Long-Term Follow-Up of 27 Patients

BACKGROUND

The optimal treatment of glomus jugulare tumors (GJTs) remains controversial. Due to the critical location, microsurgery still provides high treatment-related morbidity and a decreased quality of life. Thus, we performed stereotactical radiosurgery (SRS) for the treatment of GJTs and evaluated the long-term outcome.

METHODS

Between 1991 and 2011, 32 patients with GJTs underwent SRS using a linear accelerator (LINAC) either as primary or salvage therapy. Twenty-seven patients (median age 59.9 years, range 28.7-79.9 years) with a follow-up greater than five years (median 11 years, range 5.3-22.1 years) were selected for retrospective analysis. The median therapeutic single dose applied to the tumor surface was 15 Gy (range 11-20 Gy) and the median tumor volume was 9.5 ml (range 2.8-51 ml).

RESULTS

Following LINAC-SRS, 10 of 27 patients showed a significant improvement of their previous neurological complaints, whereas 12 patients remained unchanged. Five patients died during follow-up due to old age or other, not treatment-related reasons. MR-imaging showed a partial remission in 12 and a stable disease in 15 patients. No tumor progression was observed. The actuarial overall survival rates after five, ten and 20 years were 100%, 95.2% and 79.4%, respectively.

CONCLUSIONS

Stereotactic LINAC-Radiosurgery can achieve an excellent long-term tumor control beside a low rate of morbidity in the treatment of GJTs. It should be considered as an alternative therapy regime to surgical resection or fractionated external beam radiation either as primary, adjuvant or salvage therapy.

Connecting molecular pathways to hereditary cancer risk syndromes

An understanding of the genetic causes and molecular pathways of hereditary cancer syndromes has historically informed our knowledge and treatment of all types of cancers. For this review, we focus on three rare syndromes and their associated genetic mutations including BAP1, TP53, and SDHx (SDHA, SDHB, SDHC, SDHD, SDHAF2). BAP1 encodes an enzyme that catalyzes the removal of ubiquitin from protein substrates, and germline mutations of BAP1 cause a novel cancer syndrome characterized by high incidence of benign atypical melanocytic tumors, uveal melanomas, cutaneous melanomas, malignant mesotheliomas, and potentially other cancers. TP53 mutations cause Li-Fraumeni syndrome (LFS), a highly penetrant cancer syndrome associated with multiple tumors including but not limited to sarcomas, breast cancers, brain tumors, and adrenocortical carcinomas. Genomic modifiers for tumor risk and genotype-phenotype correlations in LFS are beginning to be identified. SDH is a mitochondrial enzyme complex involved in the tricarboxylic acid (TCA) cycle, and germline SDHx mutations lead to increased succinate with subsequent paragangliomas, pheochromocytomas, renal cell carcinomas (RCCs), gastrointestinal stromal tumors (GISTs), and other rarer cancers. In all of these syndromes, the molecular pathways have informed our understanding of tumor risk and successful early tumor surveillance and screening programs.

Stereotactic radiosurgery as the primary treatment for new and recurrent paragangliomas: is open surgical resection still the treatment of choice?

OBJECTIVE

Paragangliomas (PGs) or glomus tumors are rare, and publications comparing treatment alternatives are few. We sought to analyze our experience with stereotactic radiosurgery (SRS), review the literature, and develop treatment guidelines.

METHODS

We retrospectively examined the outcomes of 41 PGs in 36 patients treated with SRS at Stanford. Our data from medical records, telephone interviews, and imaging studies were combined with previously reported SRS data and compared to results following other treatments.

RESULTS

With a median clinical follow-up of 4.8 years (3.9 years radiographic), local control was 100%. Complications included increase in preexistent vertigo in one patient and transient cranial neuropathies in two patients. Published surgical series describe a lower local control rate as well as more frequent and severe complications. Published radiation therapy (RT) series document a slightly lower local control rate than SRS, but SRS can be delivered more quickly and conveniently. Open surgery and other combinations of treatments appear to be required for several subpopulations of PG patients.

CONCLUSIONS

We feel that SRS should be the primary treatment for most new and recurrent PGs. Even some very large PGs are appropriate for SRS. RT remains an appropriate option in some centers, especially those where SRS is not available. PGs occurring in the youngest patients, catecholamine secreting PGs, and PGs causing rapidly progressing neurologic deficits may be more appropriate for open resection. Metastatic PGs may benefit from combinations of chemotherapy and SRS or RT. Treatment guidelines are proposed.

Paraganglioma: the role of genetic counselling and radiological screening

Paragangliomas are rare tumours of the autonomic nervous system that occur in both sporadic and hereditary forms. They are usually benign tumours with low mortality, but can cause significant morbidity related to mass effect. Genetic predisposition to develop paraganglioma can occur within known tumour syndromes and familial tumours tend to present at a younger age and at multiple sites compared to sporadic tumours. Tumours should be diagnosed and excised as early as possible, as studies have shown morbidity to be directly related to tumour size. We present a case of a 14-year-old boy with multiple paraganglioma and a strong family history of paraganglioma. He suffered significant morbidity at resection of an extra-adrenal retroperitoneal tumour due to late diagnosis and was later unable to undergo excision of a head and neck paraganglioma due to its size and relation to neurovascular structures in the neck. We review the current literature on suggested genetic counselling (psychological counselling and DNA analysis) and radiological screening guidelines and recommend that genetic counselling should be offered to all patients with a family history of paraganglioma from the age of 5 years. Those positive for paternal paraganglioma locus gene should then undergo regular radiological screening with MRI.

Mutation analysis of the SDHD gene in four kindreds with familial paraganglioma: description of one novel germline mutation

The familial paraganglioma syndrome is an autosomal dominant disorder characterized by the presence of carotid body paragangliomas and, less frequently, paragangliomas of the glomus jugulare, glomus vagale, and adrenal pheochromocytomas. Germline mutations of the genes for succinate dehydrogenase subunits D, B, or C (SDHD, SDHB, SDHC) have been identified in some kindreds with familial paraganglioma. In this study, we report the clinicopathologic features of four different kindreds with familial paraganglioma, which were screened for germline mutations in the SDHD gene. DNA was obtained from tumor and normal tissue, as well as from peripheral blood. Mutation analysis was performed by single-strand conformation polymorphism analysis and DNA sequencing. SDHD germline mutations were detected in the affected family members of the four families, as well as in several asymptomatic carriers. An identical mutation in exon 4 of SDHD (334-337delACTG) was identified in two apparently unrelated kindreds. The third family showed a germline mutation in exon 2 (W43X). The mutations present in these three families had been previously described in Spanish families, suggesting a founder effect. The fourth family exhibited a mutation in exon 2 of SDHD (170-171delTT), which had not been previously identified. The affected family members of the four kindreds showed paragangliomas, located in the head and neck region, and all of them were benign. These results confirm that genetic testing of SDHD may be a powerful tool for the identification of the syndrome in patients with multiple or bilateral paragangliomas.

Complex tumors of the glomus jugulare: criteria, treatment, and outcome

Object

Tumors of the glomus jugulare are benign, slow-growing paragangliomas. Their natural history, surgical treatment, and outcome have been well addressed in the recent literature; however, there remains a subgroup of complex tumors—multiple, giant, malignant, neuropeptide-secreting lesions, and those treated previously by an intervention with an adverse outcome—that is high risk, presents surgical challenges, and is associated with treatment controversy. In this article the authors report on a series of patients with complex glomus jugulare tumors and focus on treatment decisions, avoidance of complications, surgical refinements, and patient outcomes.

Methods

In this retrospective study, the patient population was composed of 11 male and 32 female patients (mean age 47 years) with complex tumors of the glomus jugulare who were treated by the senior author within the past 20 years. These include 38 patients with giant tumors, 11 with multiple paragangliomas (seven bilateral and four ipsilateral), two with tumors that hypersecreted catecholamine, and one with a malignant tumor. Six patients had associated lesions: one dural arteriovenous malformation, one carotid artery (CA) aneurysm, two adrenal tumors, and two other cranial tumors.

All but one patient presented with neurological deficits. Cranial nerve deficits, particularly those associated with the lower cranial nerves, were the prominent feature. Twenty-eight patients underwent resection in an attempt at total removal, and gross-total resection was achieved in 24 patients. Particularly challenging were cases in which the patient had undergone prior embolization or CA occlusion, after which new feeding vessels from the internal CA and vertebrobasilar artery circulation developed.

The surgical technique was tailored to each patient and each tumor. It was modified to preserve facial nerve function, particularly in patients with bilateral tumors. Intrabulbar dissection was performed to increase the likelihood that the lower cranial nerves would be preserved. Each tumor was isolated to improve its resectability and prevent blood loss. No operative mortality occurred. In one patient hemiplegia developed postoperatively due to CA thrombosis, but the patient recovered after an endovascular injection of urokinase. In four patients a cerebrospinal fluid leak was treated through spinal drainage, and in five patients infection developed in the external ear canal. Two of these infections progressed to osteomyelitis of the temporal bone. There were two recurrences, one in a patient with a malignant tumor who eventually died of the disease.

Conclusions

Despite the challenges encountered in treating complex glomus jugulare tumors, resection is indicated and successful. Multiple tumors mandate a treatment plan that addresses the risk of bilateral cranial nerve deficits. The intra-bulbar dissection technique can be used with any tumor, as long as the tumor itself has not penetrated the wall of the jugular bulb or infiltrated the cranial nerves. Tumors that hypersecrete catecholamine require perioperative management and malignant tumors carry a poor prognosis.

Complex tumors of the glomus jugulare: criteria, treatment, and outcome

OBJECT

Tumors of the glomus jugulare are benign, slow-growing paragangliomas. Their natural history, surgical treatment, and outcome have been well addressed in the recent literature; however, there remains a subgroup of complex tumors--multiple, giant, malignant, neuropeptide-secreting lesions, and those treated previously by an intervention with an adverse outcome--that is high risk, presents surgical challenges, and is associated with treatment controversy. In this article the authors report on a series of patients with complex glomus jugulare tumors and focus on treatment decisions, avoidance of complications, surgical refinements, and patient outcomes.

METHODS

In this retrospective study, the patient population was composed of 11 male and 32 female patients (mean age 47 years) with complex tumors of the glomus jugulare who were treated by the senior author within the past 20 years. These include 38 patients with giant tumors, 11 with multiple paragangliomas (seven bilateral and four ipsilateral), two with tumors that hypersecreted catecholamine, and one with a malignant tumor. Six patients had associated lesions: one dural arteriovenous malformation, one carotid artery (CA) aneurysm, two adrenal tumors, and two other cranial tumors. All but one patient presented with neurological deficits. Cranial nerve deficits, particularly those associated with the lower cranial nerves, were the prominent feature. Twenty-eight patients underwent resection in an attempt at total removal, and gross-total resection was achieved in 24 patients. Particularly challenging were cases in which the patient had undergone prior embolization or CA occlusion, after which new feeding vessels from the internal CA and vertebrobasilar artery circulation developed. The surgical technique was tailored to each patient and each tumor. It was modified to preserve facial nerve function, particularly in patients with bilateral tumors. Intrabulbar dissection was performed to increase the likelihood that the lower cranial nerves would be preserved. Each tumor was isolated to improve its resectability and prevent blood loss. No operative mortality occurred. In one patient hemiplegia developed postoperatively due to CA thrombosis, but the patient recovered after an endovascular injection of urokinase. In four patients a cerebrospinal fluid leak was treated through spinal drainage, and in five patients infection developed in the external ear canal. Two of these infections progressed to osteomyelitis of the temporal bone. There were two recurrences, one in a patient with a malignant tumor who eventually died of the disease.

CONCLUSIONS

Despite the challenges encountered in treating complex glomus jugulare tumors, resection is indicated and successful. Multiple tumors mandate a treatment plan that addresses the risk of bilateral cranial nerve deficits. The intrabulbar dissection technique can be used with any tumor, as long as the tumor itself has not penetrated the wall of the jugular bulb or infiltrated the cranial nerves. Tumors that hypersecrete catecholamine require perioperative management and malignant tumors carry a poor prognosis.

Etiopathogenesis and clinical presentation of carotid body tumors

The carotid body (CB) is a highly specialized small organ located at the bifurcation of the common carotid artery in the neck and plays an important role in acute adaptation to hypoxia. The most common diseased state of the carotid body is its enlargement (i.e., the CB paraganglioma), which can be caused by a genetic predisposition (hereditary paraganglioma, PGL) and by chronic hypoxic stimulation. The CB is the most common tumor site in head and neck paragangliomas. Currently, inactivating germline mutations in the mitochondrial complex II subunits SDHB, SDHC, and SDHD have been identified as genetic risk factors for CB tumors (CBTs). Another locus at chromosome 11q13, identified by linkage analysis in a single family, may harbor a fourth susceptibility gene. Although CBTs are mostly slow-growing and benign, they can cause significant morbidity because of their proximity to major arteries and nerves in the head and neck. Here, we review the etiological factors implicated in the development of CBTs and provide information pertaining to their clinical presentation. Although CBTs are rare, they have the potential to provide unique insights for tumorigenesis and oxygen sensing and signaling mechanisms.

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

BACKGROUND

Paragangliomas are rare and highly heritable tumours of neuroectodermal origin that often develop in the head and neck region. Germline mutations in the mitochondrial complex II genes, SDHB, SDHC, and SDHD, cause hereditary paraganglioma (PGL).

METHODS

We assessed the frequency of SDHB, SDHC, and SDHD gene mutations by PCR amplification and sequencing in a set of head and neck paraganglioma patients who were previously managed in two otolaryngology clinics in the USA.

RESULTS

Fifty-five subjects were grouped into 10 families and 37 non-familial cases. Five of the non-familial cases had multiple tumours. Germline SDHD mutations were identified in five of 10 (50%) familial and two of 37 ( approximately 5%) non-familial cases. R38X, P81L, H102L, Q109X, and L128fsX134 mutations were identified in the familial cases and P81L was identified in the non-familial cases. Both non-familial cases had multiple tumours. P81L and R38X mutations have previously been reported in other PGL families and P81L was suggested as a founder mutation. Allelic analyses of different chromosomes carrying these mutations did not show common disease haplotypes, strongly suggesting that R38X and P81L are potentially recurrent mutations. Germline SDHB mutations were identified in two of 10 (20%) familial and one of 33 ( approximately 3%) non-familial cases. P131R and M71fsX80 were identified in the familial cases and Q59X was identified in the one non-familial case. The non-familial case had a solitary tumour. No mutations could be identified in the SDHC gene in the remaining four families and 20 sporadic cases.

CONCLUSIONS

Mutations in SDHD are the leading cause of head and neck paragangliomas in this clinic patient series. SDHD and SDHB mutations account for 70% of familial cases and approximately 8% of non-familial cases. These results also suggest that the commonness of the SDHD P81L mutation in North America is the result of both a founder effect and recurrent mutations.

The R22X mutation of the SDHD gene in hereditary paraganglioma abolishes the enzymatic activity of complex II in the mitochondrial respiratory chain and activates the hypoxia pathway

Hereditary paragangliomas are usually benign tumors of the autonomic nervous system that are composed of cells derived from the primitive neural crest. Even though three genes (SDHD, SDHC, and SDHB), which encode three protein subunits of cytochrome b of complex II in the mitochondrial respiratory chain, have been identified, the molecular mechanisms leading to tumorigenesis are unknown. We studied a family in which the father and his eldest son had bilateral neck paragangliomas, whereas the second son had a left carotid-body paraganglioma and an ectopic mediastinal pheochromocytoma. A nonsense mutation (R22X) in the SDHD gene was found in these three affected subjects. Loss of heterozygosity was observed for the maternal chromosome 11q21-q25 within the tumor but not in peripheral leukocytes. Assessment of the activity of respiratory-chain enzymes showed a complete and selective loss of complex II enzymatic activity in the inherited pheochromocytoma, that was not detected in six sporadic pheochromocytomas. In situ hybridization and immunohistochemistry experiments showed a high level of expression of markers of the angiogenic pathway. Real-time quantitative reverse transcriptase (RT)-PCR measurements confirmed that vascular endothelial growth factor and endothelial PAS domain protein 1 mRNA levels were significantly higher (three- and sixfold, respectively) than those observed in three sporadic benign pheochromocytomas. Thus, inactivation of the SDHD gene in hereditary paraganglioma is associated with a complete loss of mitochondrial complex II activity and with a high expression of angiogenic factors.

Novel mutations and the emergence of a common mutation in the SDHD gene causing familial paraganglioma

Familial paragangliomas (PGL) are slow-growing, highly vascular, generally benign neoplasms, usually of the head and neck, that arise from neural crest cells. This rare autosomal dominant disorder is highly penetrant and influenced by genomic imprinting through paternal transmission. Timely detection of these tumors may afford the affected individual the opportunity to avoid the potential serious morbidity associated with surgical removal and the mortality that may accompany local and distant metastases. Linkage to two distinct chromosomal loci, 11q13.1 and 11q23, has been previously reported. Recently, germline mutations in SDHD, a mitochondrial complex II gene on chromosome 11q23, have been demonstrated. We evaluated members of seven families with PGL, five previously studied and shown to have linkage to chromosome 11q23. The entire coding region of the SDHD gene was sequenced and yielded four novel mutations and one mutation shared in three of our unrelated families. Novel mutations found included a truncating mutation in exon 2, as well as a missense mutation, a deletion, and an insertion in exon 4. Three of our families had a common mutation in exon 3 (P81L) that has been reported and thought to be a founder mutation. A restriction enzyme assay was developed for initial screening of this mutation. Molecular analysis is now available and recommended for presymptomatic diagnosis in those at-risk individuals and for confirmatory diagnosis in those having PGL.