Identification of Isocitrate Dehydrogenase 2 (IDH2) Mutation in Carotid Body Paraganglioma.

Carotid body paragangliomas (PGLs) are rare neuroendocrine tumors that develop within the adventitia of the medial aspect of the carotid bifurcation. Carotid body PGLs comprise about 65% of head and neck paragangliomas, however, their genetic background remains elusive. In the present study, we report one case of carotid body PGL with a somatic mutation in the gene encoding isocitrate dehydrogenase 2 (IDH2). The missense mutation in IDH2 resulted in R172G amino acid substitution, which exhibits neomorphic activity and production of D-2-hydroxyglutarate.

Immunohistochemistry and Mutation Analysis of SDHx Genes in Carotid Paragangliomas.

Carotid paragangliomas (CPGLs) are rare neuroendocrine tumors often associated with mutations in SDHx genes. The immunohistochemistry of succinate dehydrogenase (SDH) subunits has been considered a useful instrument for the prediction of SDHx mutations in paragangliomas/pheochromocytomas. We compared the mutation status of SDHx genes with the immunohistochemical (IHC) staining of SDH subunits in CPGLs. To identify pathogenic/likely pathogenic variants in SDHx genes, exome sequencing data analysis among 42 CPGL patients was performed. IHC staining of SDH subunits was carried out for all CPGLs studied. We encountered SDHx variants in 38% (16/42) of the cases in SDHx genes. IHC showed negative (5/15) or weak diffuse (10/15) SDHB staining in most tumors with variants in any of SDHx (94%, 15/16). In SDHA-mutated CPGL, SDHA expression was completely absent and weak diffuse SDHB staining was detected. Positive immunoreactivity for all SDH subunits was found in one case with a variant in SDHD. Notably, CPGL samples without variants in SDHx also demonstrated negative (2/11) or weak diffuse (9/11) SDHB staining (42%, 11/26). Obtained results indicate that SDH immunohistochemistry does not fully reflect the presence of mutations in the genes; diagnostic effectiveness of this method was 71%. However, given the high sensitivity of SDHB immunohistochemistry, it could be used for initial identifications of patients potentially carrying SDHx mutations for recommendation of genetic testing.

Carotid body paragangliomas and matrix metalloproteinases.

BACKGROUND: The carotid body tumors (CBTs) are relatively rare neoplasms and may present into benign or life threatening malignant forms. Matrix metalloproteinases (MMPs) are often involved in vascular and cancer diseases. Objective of this study is to study the relationship between CBTs and MMPs. METHODS: We performed a multicenter study on 14 patients with CBTs. All tumors were resected. For each patient, we evaluated the MMPs' levels in both plasma (enzyme-linked immunosorbent assay [ELISA] test) and tissue samples (Western blot analysis). These MMPs' plasma levels were compared with the MMPs' plasma levels of healthy patients. RESULTS: Eleven patients had benign CBTs, whereas 3 patients had malignant CBTs. ELISA findings revealed significant higher levels (P < 0.01) of MMP-1, -2, -3, -8, and -9 in patients with paraganglioma with respect to healthy patients. Patients with malignant CBTs showed significantly higher levels (P < 0.01) of MMP-1, -2, and -3 compared with patients with benign CBTs. CONCLUSIONS: Because this is an exploratory study, the experience on this casuistry showed that MMPs' evaluation may help clinicians and surgeons to formulate a more rapid and clear diagnosis on CBTs' behavior. However, other studies on a large group of patients may be useful to validate these observations.

Contiguous bilateral head and neck paragangliomas in a carrier of the SDHB germline mutation.

Paragangliomas are extremely rare neoplasms with multicentric presentation usually linked to familial tumor syndromes. This patient presented with the uncommon combination of concurrent bilateral carotid body tumors and a unilateral glomus jugulare mass that demonstrated vascular continuity. During treatment, the patient was found to be heterozygous for the SDHB germline mutation, an autosomal dominant genotype of the familial paraganglioma syndromes associated with increased malignancy. The unique profile of the SDHB patient as regards primary evaluation, surgical considerations, and extended surveillance was explored and has led to a proposed treatment algorithm for these patients.

Synchronous carotid body and thoracic paraganglioma associated with a germline SDHC mutation.

Paraganglionic tumors are rare. A germline mutation responsible for a familial pattern of paragangliomas (PGLs) has been identified on the genes encoding for the subunits of succinate dehydrogenase (SDH). Manifestations of those with a succinate dehydrogenase subunit C (SDHC) germline mutation have been almost exclusively reported as single head and neck paragangliomas (HNPGLs). We present a 32-year-old man with a familial SDHC mutation who manifests synchronous PGLs of the carotid body and the thoracic aortopulmonary window. To our knowledge, this is the first report of such a presentation for this mutation.

Inhibition of succinate dehydrogenase dysregulates histone modification in mammalian cells.

Remodelling of mitochondrial metabolism is a hallmark of cancer. Mutations in the genes encoding succinate dehydrogenase (SDH), a key Krebs cycle component, are associated with hereditary predisposition to pheochromocytoma and paraganglioma, through mechanisms which are largely unknown. Recently, the jumonji-domain histone demethylases have emerged as a novel family of 2-oxoglutarate-dependent chromatin modifiers with credible functions in tumourigenesis. Using pharmacological and siRNA methodologies we show that increased methylation of histone H3 is a general consequence of SDH loss-of-function in cultured mammalian cells and can be reversed by overexpression of the JMJD3 histone demethylase. ChIP analysis revealed that the core promoter of IGFBP7, which encodes a secreted protein upregulated after loss of SDHB, showed decreased occupancy by H3K27me3 in the absence of SDH. Finally, we provide the first evidence that the chief (type I) cell is the major methylated histone-immunoreactive constituent of paraganglioma. These results support the notion that loss of mitochondrial function alters epigenetic processes and might provide a signature methylation mark for paraganglioma.

Role of the genetic study in the management of carotid body tumor in paraganglioma syndrome.

Diagnosis of carotid body tumor (CBT) was made in a 36 years old woman. The pre-operative examination included genetic analysis of the succinate dehydrogenase that showed a mutation in his subunit D responsible of multiple paraganglioma at slow growth. Subsequently a thoraco-abdominal CT and indium(111) octreotide body scan were performed and another paraganglioma was detected in the anterior mediastinum. CBT was surgically removed; differently the thoracic lesion due to his benign genetic profile was not treated. During a 3-years follow-up the thoracic paraganglioma as expected, didn't increase. Genetic analysis of succinate dehydrogenase, should be performed in the management of CBT.

Increased urinary dopamine excretion in association with bilateral carotid body tumours-- clinical, biochemical and genetic findings.

This report describes a rare case of a patient with increased urinary dopamine excretion in association with bilateral carotid body tumours. Excretion of adrenaline, noradrenaline, metadrenaline, normetadrenaline and 4-hydroxy-3-methoxymandelic acid (HMMA) were within the reference ranges, and an (123)I-meta-iodobenzylguanidine (MIBG) scan showed uptake in the neck masses, with no other abnormal uptake anywhere else in the body. The patient is being managed conservatively as the tumours are not amenable to resection on account of their size and vascularity. There are only four previous case reports of dopamine-secreting tumours of the carotid body described in the literature, all of whom were women. The tumours were unilateral in three cases and bilateral in the fourth case. Familial cases of carotid body tumours have a higher prevalence of bilateral tumours than non-familial cases. Recent reports in the literature have suggested that a significant number of patients with extra-adrenal catecholamine-secreting paragangliomas have a genetic mutation in one of the identified susceptibility genes for catecholamine-secreting tumours, despite having no other affected family members, and a mutation has been found in the succinate dehydrogenase gene for this patient.

Carotid body paraganglioma and SDHD mutation in a Greek family.

BACKGROUND: Carotid body (CB) is a highly specialized paraganglion originating from the neural crest ectoderm. CB paraganglion can be caused either by a genetic predisposition (hereditary paraganglia) or by chronic hypoxic stimulation. Germline mutations in any of the following genes: SDHD, SDHC, SDHB, PGL2 or other unknown genes, can cause paragangliomas (PGLs). MATERIALS AND METHODS: We studied a Greek family in which the two daughters had carotid body paraganglioma, whereas both parents did not. RNA extraction, reverse transcriptase polymerase chain reaction and direct DNA sequencing were performed, in order to identify SDHD mutations in all four exons. RESULTS: Our results revealed the existence of the missense mutation Y114C, in exon-4 of the SDHD gene, in the unaffected father and both affected sisters. CONCLUSION: DNA testing was performed, for the first time in Greece, on patients with carotid body tumor. This marks a new geographical location, in the literature, for this mutation.

Active succinate dehydrogenase (SDH) and lack of SDHD mutations in sporadic paragangliomas.

BACKGROUND: Paragangliomas are benign, slow-growing tumours of the head and neck region. The candidate gene for familial and some sporadic paragangliomas, SDHD (succinate dehydrogenase, subunit D), has been mapped to the PGL1 locus in 11q23.3. MATERIALS AND METHODS: Normal and tumour DNA of 17 patients with sporadic paragangliomas were analysed by sequencing (SDHD, SDHB and SDHC genes), fluorescence in situ hybridisation (FISH). In addition, loss of heterozygosity (LOH) and succinate dehydrogenase (SDH) enzyme activity assays were performed. RESULTS AND CONCLUSION: Only two patients from our collective showed SDH gene mutations, one in SDHD and one in SDHB, respectively. Moreover, SDH activity detected in 5/8 patients confirmed the fact that SDH inactivation is not a major event in sporadic paragangliomas. LOH and FISH analysis demonstrated a frequent loss of regions within chromosome 11, indicating that additional genes in 11q may play a role in tumour genesis of sporadic paragangliomas.

Novel mutations in the SDHD gene in pedigrees with familial carotid body paraganglioma and sensorineural hearing loss.

Paraganglioma (PGL) is a rare disorder characterized by tumors of the head and neck region. Between 10% and 50% of cases of PGL are familial, and the disease is autosomal dominant and subject to age-dependent penetrance and imprinting. The paraganglioma gene (PGL1) has been mapped to 11q22.3-q23, and recently germline mutations in the SDHD gene have been identified. The SDHD region contains another gene, DPP2/TIMM8B, the homolog of which causes dystonia and deafness seen in Mohr-Tranebjaerg syndrome. Using four PGL pedigrees, two of which exhibit coinheritance of PGL and sensorineural hearing loss or tinnitus, analysis of 14 microsatellite markers provided support for linkage to the PGL1 locus. Sequence analysis identified novel mutations in exon 1 and exon 3 of the SDHD gene, including a novel two base pair deletion in exon 3 creating a premature stop codon at position 67; a novel three base pair deletion in exon 3 resulting in the loss of Tyr-93; a missense mutation in exon 3 resulting in the substitution of Leu-81 for Pro-81; and a novel G-to-C substitution in exon 1 resulting in the substitution of Met-1 for Ile-1. No base changes were detected in the DPP2/TIMM8B gene. There was no apparent loss of heterozygosity at the site of the SDHD mutations. However, RT-PCR analysis of tumor samples showed monoallelic expression of the mutant (paternal) allele as expected for imprinting. This has not previously been shown for this disorder. The inheritance and expression of the SDHD gene is consistent with the PGL1 gene being subject to genomic imprinting.

[Risk of endocrine activation in interventions of paragangliomas in the head-neck area]. / Zum Risiko endokriner Aktivierung bei Eingriffen an Paragangliomen im Kopf-Hals-Bereich.

The intracytoplasmatic glycolytic enzyme neuron-specific enolase (NSE) can be found in cells of endocrine tissue and their derived tumours. The enzyme is not secreted but released if cells are destroyed, i.e. continuously in malignant tumours. The serum level of neuron-specific enolase (NSE) has been used as a marker for small cell carcinomas of the lung, glioblastomas and malignant phaeochromocytomas. In this investigation blood samples were taken prior to and following surgical manipulation of the tumour in 21 patients with paragangliomas of the head and neck region and 6 controls. 22 serum samples were obtained before angiography and two hours after angiography, 41 before surgery, during surgery and after surgery. The serum level of NSE was measured by NSE-RIA test (Diagnostics, Uppsala). In all tumour specimens NSE could be demonstrated by the immunohistological PAP method (Abb. 1). Only two patients had preoperatively elevated serum-NSE levels. An arterial venous shunt had been detected by angiography in one of these patients. No significant effect on NSE serum level could be produced in the majority of patients by an angiography with embolisation or surgical manipulation of the tumour (Fig. 1, 2). A reduction in serum NSE level was observed postoperatively in both cases mentioned before. None of the 6 controls showed any significant change in serum NSE level (Fig. 3). It can be concluded from this study that embolisation does not lead to direct or indirect cell destruction through ischaemia. Manipulation of the tumour does not destroy a significant number of cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Paragangliomas of the craniocervical region. An immunohistochemical study on tyrosine hydroxylase.

An immunohistochemical study on tyrosine hydroxylase (TH), a rate-limiting enzyme in the catecholamine synthesizing pathway, was made on three craniocervical region paragangliomas, two of which showed metastases to the cervical lymph nodes. In all of the original tumors, the majority of tumor cells showed positive immunostaining for TH of variable intensity in their cytoplasm regardless of their cytological features such as cellular and nuclear pleomorphism. The finding suggests that most tumor cells are capable of production of catecholamines and are derived from chief cells in the normal paraganglia. In cervical lymph nodes, however, no positive immunostaining for TH was observed in metastatic tumor cells, in contrast with the findings in the original tumors. The absence of TH immunoreactivity in metastatic tumor cells appears to be noteworthy in considering their malignant potential. Application of the TH immunohistochemistry to further cases appears important for the better understanding of this neoplasm, a catecholamine-producing tumor.

Paragangliomas of the head and neck: ultrastructural and immunohistochemical analysis.

Eighteen head and neck paragangliomas were studied by light microscopy and light microscopic immunohistochemistry by the peroxidase technique for the presence of NSE (neuron-specific enolase), serotonin, and a battery of neuropeptides. Seven of these tumors were also studied by electron microscopy. All 18 cases demonstrated immunostaining for NSE; 10 of the 11 carotid body tumors had immunostaining for multiple hormones. Considering all 18 cases, the most frequently demonstrated hormonal substances were in order: serotonin, leu-enkephalin, gastrin, substance P, vasoactive intestinal polypeptide (VIP), somatostatin, bombesin, calcitonin, and alpha MSH. In several tumors, adjacent-step sections stained for different hormonal substances strongly suggested reactivity for more than one hormone in given tumor cells. By electron microscopy, all 7 cases studied displayed considerable heterogeneity of the neurosecretory granules with respect to size, shape, and electron density. This demonstrated that branchiomeric paragangliomas are capable of producing a spectrum of neuropeptides in addition to their known amine content. The presence of immunoreactive serotonin in most of these neoplasms was confirmed. In addition to these findings, neurofibrils within the substance of carotid body paragangliomas demonstrated immunoreactivity for somatostatin and a gastrinlike neuropeptide. The significance of the neuropeptides in these neoplasms and their possible presence and role in normal and hyperplastic paraganglia remain to be defined.

Tissue culture, electron microscopic and enzyme histochemical investigations of extraadrenal paragangliomas.

Light and electromicroscopical as well as histochemical investigations were performed on three cases of extraadrenal paragangliomas. They were localized in the carotid body, tympanicum and cauda equina region. Tissue of two cases was cultivated in vitro in nutrient medium TCM 199. The tumours were classified as paragangliomas of the paraganglionic type with typical cell clusters, of the adenomatous and angiomatous type. The enzyme histochemistry showed a very high dehydrogenase activity. Ultrastructurally numerous typical osmiophilic granules could be observed in the cytoplasm of the tumour cells. In tissue culture only a minimal cellular proliferative activity could be detected. The few proliferating cell colonies showed mostly characteristics of epithelial tissue and sometimes a similar behaviour to cells of a ganglioneuroblastoma. The minimal proliferative activity in vitro is in good agreement with the proliferative behaviour of the extraadrenal paragangliomas in vivo.