Multiple pheochromocytomas and paragangliomas in a young patient carrying a SDHD gene mutation

Clinical Practice Guidance: Surveillance for phaeochromocytoma and paraganglioma in paediatric succinate dehydrogenase gene mutation carriers

The succinate dehydrogenase (SDH) enzyme complex functions as a key enzyme coupling the oxidation of succinate to fumarate in the citric acid cycle. Inactivation of this enzyme complex results in the cellular accumulation of the oncometabolite succinate, which is postulated to be a key driver in tumorigenesis. Succinate accumulation inhibits 2-oxoglutarate-dependent dioxygenases, including DNA and histone demethylase enzymes and hypoxic gene response regulators. Biallelic inactivation (typically resulting from one inherited and one somatic event) at one of the four genes encoding the SDH complex (SDHA/B/C/D) is the most common cause for SDH deficient (dSDH) tumours. Germline mutations in the SDHx genes predispose to a spectrum of tumours including phaeochromocytoma and paraganglioma (PPGL), wild type gastrointestinal stromal tumours (wtGIST) and, less commonly, renal cell carcinoma and pituitary tumours. Furthermore, mutations in the SDHx genes, particularly SDHB, predispose to a higher risk of malignant PPGL, which is associated with a 5-year mortality of 50%. There is general agreement that biochemical and imaging surveillance should be offered to asymptomatic carriers of SDHx gene mutations in the expectation that this will reduce the morbidity and mortality associated with dSDH tumours. However, there is no consensus on when and how surveillance should be performed in children and young adults. Here, we address the question: "What age should clinical, biochemical and radiological surveillance for PPGL be initiated in paediatric SDHx mutation carriers?".

Allelic loss of chromosomes 8 and 19 in MENX-associated rat pheochromocytoma

Pheochromocytomas are neoplasias of neural crest origin that arise from the chromaffin cells of the adrenal medulla. Pheochromocytomas arise with complete penetrance in rats homozygous for a germ-line frameshift mutation of Cdkn1b, encoding the cell cycle inhibitor p27KIP1 (MENX syndrome). We performed a genome-wide scan for allelic imbalance comparing 20 rat pheochromocytoma DNAs with normal rat DNA to better understand the pathobiology of the tumors and to correlate the findings with human pheochromocytoma. We identified allelic imbalance (AI) at candidate regions on rat chromosomes 8 and 19. Interestingly, the regions often lost in rat tumors are syntenic to regions involved in human pheochromocytomas. Fluorescence in situ hybridization analysis further validated the AI data. Sdhd and Rassf1a were analyzed in detail as they map to regions of AI on chromosome 8 and their homologues are implicated in human pheochromocytoma: we found no genetic mutations nor decreased expression. We also analyzed additional candidate genes, that is, rat homologues of genes predisposing to human pheochromocytoma and known tumor-suppressor genes, but we found no AI. In contrast, we observed frequent overexpression of Cdkn2a and Cdkn2c, encoding the cell cycle inhibitors p16INK4a and p18INK4c, respectively. The relative small number of allelic changes we found in rat pheochromocytoma might be related to their nonmalignant status and losses at chromosomes 8 and 19 are events that precede malignancy. Because of the high concordance of affected loci between rat and human tumors, studies of the MENX-associated pheochromocytomas should facilitate the identification of novel candidate genes implicated in their human counterpart.

Phaeochromocytomas and sympathetic paragangliomas

BACKGROUND

About 24 per cent of phaeochromocytomas (PCCs) and sympathetic paragangliomas (sPGLs) appear in familial cancer syndromes, including multiple endocrine neoplasia type 2, von Hippel-Lindau disease, neurofibromatosis type 1 and PCC-paraganglioma syndrome. Identification of these syndromes is of prime importance for patients and their relatives. Surgical resection is the treatment of choice for both PCC and sPGL, but controversy exists about the management of patients with bilateral or multiple tumours.

METHODS

Relevant medical literature from PubMed, Ovid and Embase websites until 2009 was reviewed for articles on PCC, sPGL, hereditary syndromes and their treatment.

DISCUSSION

Genetic testing for these syndromes should become routine clinical practice for those with PCC or sPGL. Patients should be referred to a clinical geneticist. Patients and family members with proven mutations should be entered into a standardized screening protocol. The preferred treatment of PCC and PGL is surgical resection; to avoid the lifelong consequences of bilateral adrenalectomy, cortex-sparing adrenalectomy is the treatment of choice.

SDH mutations in tumorigenesis and inherited endocrine tumours: lesson from the phaeochromocytoma-paraganglioma syndromes

A genetic predisposition for paragangliomas and adrenal or extra-adrenal phaeochromocytomas was recognized years ago. Beside the well-known syndromes associated with an increased risk of adrenal phaeochromocytoma, Von Hippel Lindau disease, multiple endocrine neoplasia type 2 and neurofibromatosis type 1, the study of inherited predisposition to head and neck paragangliomas led to the discovery of the novel 'paraganglioma-phaeochromocytoma syndrome' caused by germline mutations in three genes encoding subunits of the succinate dehydrogenase (SDH) enzyme (SDHB, SDHC and SDHD) thus opening an unexpected connection between mitochondrial tumour suppressor genes and neural crest-derived cancers. Germline mutations in SDH genes are responsible for 6% and 9% of sporadic paragangliomas and phaeochromocytomas, respectively, 29% of paediatric cases, 38% of malignant tumours and more than 80% of familial aggregations of paraganglioma and phaeochromocytoma. The disease is characterized by autosomal dominant inheritance with a peculiar parent-of-origin effect for SDHD mutations. Life-time tumour risk seems higher than 70% with variable clinical manifestantions depending on the mutated gene. In this review we summarize the most recent knowledge about the role of SDH deficiency in tumorigenesis, the spectrum and prevalence of SDH mutations derived from several series of cases, the related clinical manifestantions including rare phenotypes, such as the association of paragangliomas with gastrointestinal stromal tumours and kidney cancers, and the biological hypotheses attempting to explain genotype to phenotype correlation.

The role of 18F-FDOPA and 18F-FDG-PET in the management of malignant and multifocal phaeochromocytomas

BACKGROUND

(18)F-DOPA has emerged as a promising tool in the localization of chromaffin-tissue-derived tumours. Interestingly, phaeochromocytomas (PHEO) are also FDG avid.

AIM AND METHODS

The aim of this study was to retrospectively evaluate the results of (18)F-FDOPA and/or (18)F-FDG-PET in patients with PHEO and paragangliomas (PGLs) and to compare the outcome of this approach with the traditional therapeutic work-up. Nine patients with non-MEN2 related PHEO or PGL were evaluated. At the time of the PET studies, the patients were classified into three groups based on their clinical history, conventional and SPECT imaging. The groups were malignant disease (n = 5, 1 VHL), apparently unique tumour site in patients with previous surgery (n = 1, SDHB) and multifocal tumours (n = 3, 1 VHL, 1 SDHD). (18)F-FDOPA and (18)F-FDG-PET PET/CT were then performed in all patients.

RESULTS

PET successfully identified additional tumour sites in five out of five patients with metastatic disease that had not been identified with SPECT + CI. Whilst tumour tracer uptake varied between patients it exhibited a consistently favourable residence time for delayed acquisitions. (18)F-FDOPA uptake (SUVmax) was superior to (18)F-FDG uptake in cases of neck PGL (three patients, four tumours). If only metastatic forms and abdominal PGLs were considered, (18)F-FDG provided additional information in three cases (two metastatic forms, one multifocal disease with SDHD mutation) compared to (18)F-FDOPA.

CONCLUSIONS

Our results suggest that tumour staging can be improved by combining (18)F-FDOPA and (18)F-FDG in the preoperative work-up of patients with abdominal and malignant PHEOs. (18)F-FDOPA is also an effective localization tool for neck PGLs. MIBG however, still has a role in these patients as MIBG and FDOPA images did not completely overlap.

Multiple catecholamine-secreting paragangliomas: diagnosis after hemorrhagic stroke in a young woman

OBJECTIVE

To describe a case of multiple catecholamine-secreting paragangliomas, with a hemorrhagic stroke as the main clinical manifestation.

METHODS

We present a case report with clinical, laboratory, histologic, and genetic details.

RESULTS

A 23-year-old woman with a history of hypertension treated with orally administered medications presented to our emergency department because of sudden onset of hemiplegia of the left side of the body. A computed tomographic scan of the brain showed a right frontoparietal hematoma, and her blood pressure was 185/115 mm Hg. She was admitted to the Department of Neurosurgery, and an external drain was inserted to evacuate the hematoma. She was then referred to the Department of Clinical Sciences, where a search for possible secondary causes of hypertension was undertaken. Substantially elevated urinary levels of vanillylmandelic acid and metanephrines were found, and a pheochromocytoma was suspected. Abdominal computed tomographic scans revealed a large retroperitoneal mass (3.6 by 4 cm) and similar smaller lesions in the right adrenal gland, between the aorta and the vena cava, and in the left paraaortic area. Iodine I 123 metaiodobenzylguanidine scintigraphy showed high uptake in those same areas, consistent with the diagnosis of multiple catecholamine-secreting paragangliomas. After adequate control of the patient's hypertension was achieved with an alpha1-adrenergic receptor blocker, a Ca2+ antagonist, and a beta-adrenergic blocking agent, the tumors were excised in the Department of Surgery. The histopathologic findings confirmed the diagnosis of multiple paragangliomas. The genetic analysis demonstrated an exon 4 mutation in codon 109 (CAA>TAA, Gln>Stop) of the SDHD gene.

CONCLUSION

Although cerebral hemorrhage is an unusual complication of pheochromocytomas or paragangliomas, early recognition of the characteristic symptoms of headache, palpitations, and diaphoresis in a patient with hypertension and prompt appropriate intervention can minimize the morbidity associated with such tumors and prevent a potentially fatal outcome.

Cardiac Pheochromocytomas Detected by Tc-99m-Hydrazinonicotinyl-Tyr3-Octreotide (HYNIC-TOC) Scintigraphy

Primary pheochromocytomas of the heart are extremely rare tumors and difficult to diagnose. Iodine labeled metaiodobenzylguanidine (MIBG) is the first choice of the nuclear medicine modality in the evaluation of adrenal pheochromocytoma. However, the sensitivity of MIBG in the diagnosis of extraadrenal pheochromocytoma is less optimal. In this preliminary report, the efficacy of octreotide scintigraphy using Tc-99m labeled hydrazinonicotinyl-Tyr3-octreotide (HYNIC-TOC) in the evaluation of primary cardiac pheochromocytoma was assessed.