Karel Pacak

Pheochromocytoma and Paraganglioma: An Endocrine Society Clinical Practice Guideline

OBJECTIVE The aim was to formulate clinical practice guidelines for pheochromocytoma and paraganglioma (PPGL). PARTICIPANTS The Task Force included a chair selected by the Endocrine Society Clinical Guidelines Subcommittee (CGS), seven experts in the field, and a methodologist. The authors received no corporate funding or remuneration. EVIDENCE This evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence. The Task Force reviewed primary evidence and commissioned two additional systematic reviews. CONSENSUS PROCESS One group meeting, several conference calls, and e-mail communications enabled consensus. Committees and members of the Endocrine Society, European Society of Endocrinology, and Americal Association for Clinical Chemistry reviewed drafts of the guidelines. CONCLUSIONS The Task Force recommends that initial biochemical testing for PPGLs should include measurements of plasma free or urinary fractionated metanephrines. Consideration should be given to preanalytical factors leading to false-positive or false-negative results. All positive results require follow-up. Computed tomography is suggested for initial imaging, but magnetic resonance is a better option in patients with metastatic disease or when radiation exposure must be limited. (123)I-metaiodobenzylguanidine scintigraphy is a useful imaging modality for metastatic PPGLs. We recommend consideration of genetic testing in all patients, with testing by accredited laboratories. Patients with paraganglioma should be tested for SDHx mutations, and those with metastatic disease for SDHB mutations. All patients with functional PPGLs should undergo preoperative blockade to prevent perioperative complications. Preparation should include a high-sodium diet and fluid intake to prevent postoperative hypotension. We recommend minimally invasive adrenalectomy for most pheochromocytomas with open resection for most paragangliomas. Partial adrenalectomy is an option for selected patients. Lifelong follow-up is suggested to detect recurrent or metastatic disease. We suggest personalized management with evaluation and treatment by multidisciplinary teams with appropriate expertise to ensure favorable outcomes.

Impaired Chronotropic and Vasodilator Reserves Limit Exercise Capacity in Patients With Heart Failure and a Preserved Ejection Fraction

Background— Nearly half of patients with heart failure have a preserved ejection fraction (HFpEF). Symptoms of exercise intolerance and dyspnea are most often attributed to diastolic dysfunction; however, impaired systolic and/or arterial vasodilator reserve under stress could also play an important role. Methods and Results— Patients with HFpEF (n=17) and control subjects without heart failure (n=19) generally matched for age, gender, hypertension, diabetes mellitus, obesity, and the presence of left ventricular hypertrophy underwent maximal-effort upright cycle ergometry with radionuclide ventriculography to determine rest and exercise cardiovascular function. Resting cardiovascular function was similar between the 2 groups. Both had limited exercise capacity, but this was more profoundly reduced in HFpEF patients (exercise duration 180±71 versus 455±184 seconds; peak oxygen consumption 9.0±3.4 versus 14.4±3.4 mL · kg−1 · min−1; both P<0.001). At matched low-level workload, HFpEF subjects displayed ≈40% less of an increase in heart rate and cardiac output and less systemic vasodilation (all P<0.05) despite a similar rise in end-diastolic volume, stroke volume, and contractility. Heart rate recovery after exercise was also significantly delayed in HFpEF patients. Exercise capacity correlated with the change in cardiac output, heart rate, and vascular resistance but not end-diastolic volume or stroke volume. Lung blood volume and plasma norepinephrine levels rose similarly with exercise in both groups. Conclusions— HFpEF patients have reduced chronotropic, vasodilator, and cardiac output reserve during exercise compared with matched subjects with hypertensive cardiac hypertrophy. These limitations cannot be ascribed to diastolic abnormalities per se and may provide novel therapeutic targets for interventions to improve exercise capacity in this disorder.

Recent advances in genetics, diagnosis, localization, and treatment of pheochromocytoma.

Dr. Karel Pacak (Pediatric and Reproductive Endocrinology Branch, National Institute of Child Health and Human Development [NICHD] and Clinical Neurocardiology Section, National Institute of Neurological Disorders and Stroke [NINDS], National Institutes of Health [NIH], Bethesda, Maryland): Pheochromocytomas are chromaffin cell tumors that, although rare, must be considered in patients with hypertension, autonomic disturbances, panic attacks, adrenal incidentalomas, or familial diseases featuring a predisposition to develop pheochromocytoma. Hypertension, whether sustained or paroxysmal, is the most common clinical sign, and headache, excessive truncal sweating, and palpitations are the most common symptoms (1). Pallor is also common, whereas flushing occurs less frequently. Some patients present with severe episodes of anxiety, nervousness, or panic. Patients with a familial predisposition or small incidentally discovered adrenal masses can be normotensive and asymptomatic. The low pretest prevalence of pheochromocytomaclose to 0.5% among those tested because of hypertension and suggestive symptoms (1) and as high as 4% in patients with adrenal incidentaloma (2)together with imperfect sensitivity and specificity of commonly used biochemical and imaging tests, can make diagnosis and localization of pheochromocytoma difficult. Effective methods for diagnosis and localization are important because seemingly mild stimuli can provoke the tumor to release large amounts of catecholamines, with severe or fatal consequences. Moreover, surgical removal can cure pheochromocytoma in up to 90% of cases, whereas if left untreated the tumor can prove fatal. Advances in genetic mutation analysis have greatly improved identification of patients with familial pheochromocytoma, allowing detection of tumors at an early stage, often before typical signs and symptoms occur. These advances provide new insights into the biology and natural history of the disease and highlight inadequacies of commonly used diagnostic tests. In turn, new developments have been made in the management of patients with familial pheochromocytoma and in surgical procedures for preserving normal adrenal cortical tissue in persons with bilateral adrenal tumors. In this paper, we summarize advances in the genetics, biochemical diagnosis, localization, and management of pheochromocytoma and also note key questions that remain unanswered. Molecular Genetic Abnormalities Associated with Pheochromocytoma Drs. W. Marston Linehan and McClellan M. Walther (Urologic Oncology Branch, National Cancer Institute [NCI], NIH, Bethesda, Maryland): Pheochromocytomas may be classified as sporadic or familial. Most pheochromocytomas are sporadic. Familial predisposition is seen mainly in patients with multiple endocrine neoplasia type II (MEN II), von HippelLindau disease, neurofibromatosis type 1, and familial carotid body tumors (Table 1). The exact molecular mechanisms by which the hereditary mutations predispose to tumor development remain unknown. Hereditary forms of pheochromocytoma can differ in rate of tumor growth, malignant potential, and catecholamine phenotype. Table 1. Hereditary Forms of Pheochromocytoma Cancer Genes Identification of a cancer gene can help us understand the origin of cancer, such as pheochromocytoma, and elucidate mechanisms of tumor formation and behavior. Moreover, identification of a disease gene provides a method for genetic diagnosis. Phenotypic manifestations of a hereditary cancer syndrome can vary markedly, and genetic tests can confirm the diagnosis when the clinical presentation is complex. Finally, understanding of cancer genes may provide targets for therapy. The two most studied types of cancer genes are tumor suppressor genes (Figure 1) and oncogenes (7). When mutated, a proto-oncogene becomes activated, resulting in an oncogene. This is referred to as a single hit; that is, the proto-oncogene undergoes a single activating mutation that turns it into an oncogene (8, 9). Familial predisposition to pheochromocytoma in patients with MEN II results from such a mechanism. In contrast, a tumor suppressor gene is a loss-of-function gene, in which inactivation of both copies of the gene causes unregulated cell growth and division. This loss of function can result from mutation of one allele of a tumor suppressor gene and deletion of the second copy (10). Examples of tumor suppressor genes are the retinoblastoma gene, the Wilms tumor gene, the tuberous sclerosis genes, and, in the case of pheochromocytoma, the von HippelLindau gene (11-19). Figure 1. The Knudson two-hit model. Pheochromocytoma in Multiple Endocrine Neoplasia Type II: RETGene Multiple endocrine neoplasia type IIA is characterized clinically by the familial association of medullary thyroid cancer, pheochromocytoma, and parathyroid hyperplasia. Mucosal ganglioneuromas are also found in some patients (MEN IIB). Pheochromocytoma in MEN II is associated with germline mutation of the proto-oncogene RET. This proto-oncogene becomes an oncogene when an activating mutation occurs (20-25). The activating mutation in the RETgene drives the abnormal cellular proliferation that leads to adrenal medullary hyperplasia and pheochromocytoma. Several RETgermline mutations are associated with the development of pheochromocytoma, with some variation dependent on the particular mutation (3-5, 26, 27) (Table 1). Pheochromocytoma in von HippelLindau Disease: the von HippelLindau Gene Patients with von HippelLindau disease have a germline mutation of the von HippelLindau gene (28). Affected persons can develop early-onset bilateral kidney tumors and cysts, pheochromocytomas, cerebellar and spinal hemangioblastomas, retinal angiomas, pancreatic cysts and tumors, epididymal cystadenomas, and tumors in the endolymphatic sac canal of the inner ear (29-31). von HippelLindau disease has marked phenotypic heterogeneity. While patients from some families present with central neural, eye, kidney, and pancreatic tumors, patients in other families present mainly with pheochromocytoma (30, 32, 33). Some reports have described families thought to have familial pheochromocytoma who proved to have von HippelLindau disease (32, 34-37). Missense mutations in the von HippelLindau gene are associated with the development of pheochromocytoma more than twice as often as are other types of mutations (74% vs. 32%) (6, 33). Molecular Genetic Diagnosis von HippelLindau disease and MEN II have a similar prevalence (approximately 1 in 30 000 to 1 in 45 500). Mutations predisposing to pheochromocytoma have greater penetrance in MEN II than in von HippelLindau disease (38, 39). Pheochromocytoma in von HippelLindau families has been reported as familial pheochromocytoma or MEN II (40, 41). Because different kindreds can present with different phenotypes, it can be difficult to distinguish between von HippelLindau disease and MEN II in some patients with familial pheochromocytoma. Patients with bilateral adrenal, recurrent, or multifocal pheochromocytoma should undergo clinical or genetic testing for mutations of the von HippelLindau or RETgenes. The availability of germline testing for both von HippelLindau (42) and RET (15, 20, 23, 40, 43) gene mutations (at OncorMed in Gaithersburg, Maryland, and at the University of Pennsylvania in Philadelphia) has improved the clinical management of patients with hereditary pheochromocytoma. When a patient presents with a family history in which the primary manifestation is pheochromocytoma, the von HippelLindau gene is a likely cause. Some von HippelLindau families present mainly with pheochromocytoma and occult or delayed manifestations in the central nervous system, eye, or other organs. It is less likely that a member of a MEN II family will present predominantly with pheochromocytoma because most of these patients have medullary thyroid carcinoma (44). A small number of families with familial pheochromocytoma have neither von HippelLindau nor RETgermline mutations, and the genetic basis for this is currently being studied. Biochemical Diagnosis of Pheochromocytoma Dr. Graeme Eisenhofer (Clinical Neurocardiology Section, NINDS, NIH, Bethesda, Maryland): Diagnosis of pheochromocytoma usually requires biochemical evidence of excessive catecholamine production by the tumor, usually achieved from measurements of catecholamines or catecholamine metabolites in urine or plasma. These biochemical approaches, however, have several limitations. Since catecholamines are normally produced by sympathetic nerves and by the adrenal medulla, high catecholamine levels are not specific to pheochromocytoma and may accompany other conditions or disease states. In addition, sometimes pheochromocytomas do not secrete enough catecholamines to produce positive test results or typical signs and symptoms. In addition, pheochromocytomas often secrete catecholamines episodically. Between episodes, levels of catecholamines may be normal. Thus, commonly used tests of plasma or urinary catecholamines and metabolites and other biochemical tests, such as measurements of plasma chromogranin A levels, do not always reliably exclude or confirm a tumor (45-55). A recently developed biochemical test, involving measurements of plasma levels of free metanephrines (o-methylated metabolites of catecholamines), circumvents many of the above problems and offers a more effective means to diagnose pheochromocytoma than other tests (46, 56). Sensitivity of Biochemical Tests Measurements of plasma levels of normetanephrine and metanephrine have higher sensitivity than other biochemical tests for diagnosis of both sporadic and familial pheochromocytoma (46, 56). In familial pheochromocytoma, periodic screening can lead to early-stage detection before symptoms and signs, when tumors are small and are not secreting large amounts of catecholamines (6). The difficulty of biochemical diagnosis of familial pheochromocytoma is illustrated

Pheochromocytoma: Recommendations for clinical practice from the First International Symposium

The First International Symposium on Pheochromocytoma, held in October 2005, included discussions about developments concerning these rare catecholamine-producing tumors. Recommendations were made during the symposium for biochemical diagnosis, localization, genetics, and treatment. Measurement of plasma or urinary fractionated metanephrines, the most accurate screening approach, was recommended as the first-line test for diagnosis; reference intervals should favor sensitivity over specificity. Localization studies should only follow reasonable clinical evidence of a tumor. Preoperative pharmacologic blockade of circulatory responses to catecholamines is mandatory. Because approximately a quarter of tumors develop secondary to germ-line mutations in any one of five genes, mutation testing should be considered; however, it is not currently cost effective to test every gene in every patient. Consideration of tumor location, presence of multiple tumors, presence of metastases, and type of catecholamine produced is useful in deciding which genes to test. Inadequate methods to distinguish malignant from benign tumors and a lack of effective treatments for malignancy are important problems requiring further resolution.

An immunohistochemical procedure to detect patients with paraganglioma and phaeochromocytoma with germline SDHB, SDHC, or SDHD gene mutations: a retrospective and prospective analysis.

BACKGROUND Phaeochromocytomas and paragangliomas are neuro-endocrine tumours that occur sporadically and in several hereditary tumour syndromes, including the phaeochromocytoma-paraganglioma syndrome. This syndrome is caused by germline mutations in succinate dehydrogenase B (SDHB), C (SDHC), or D (SDHD) genes. Clinically, the phaeochromocytoma-paraganglioma syndrome is often unrecognised, although 10-30% of apparently sporadic phaeochromocytomas and paragangliomas harbour germline SDH-gene mutations. Despite these figures, the screening of phaeochromocytomas and paragangliomas for mutations in the SDH genes to detect phaeochromocytoma-paraganglioma syndrome is rarely done because of time and financial constraints. We investigated whether SDHB immunohistochemistry could effectively discriminate between SDH-related and non-SDH-related phaeochromocytomas and paragangliomas in large retrospective and prospective tumour series. METHODS Immunohistochemistry for SDHB was done on 220 tumours. Two retrospective series of 175 phaeochromocytomas and paragangliomas with known germline mutation status for phaeochromocytoma-susceptibility or paraganglioma-susceptibility genes were investigated. Additionally, a prospective series of 45 phaeochromocytomas and paragangliomas was investigated for SDHB immunostaining followed by SDHB, SDHC, and SDHD mutation testing. FINDINGS SDHB protein expression was absent in all 102 phaeochromocytomas and paragangliomas with an SDHB, SDHC, or SDHD mutation, but was present in all 65 paraganglionic tumours related to multiple endocrine neoplasia type 2, von Hippel-Lindau disease, and neurofibromatosis type 1. 47 (89%) of the 53 phaeochromocytomas and paragangliomas with no syndromic germline mutation showed SDHB expression. The sensitivity and specificity of the SDHB immunohistochemistry to detect the presence of an SDH mutation in the prospective series were 100% (95% CI 87-100) and 84% (60-97), respectively. INTERPRETATION Phaeochromocytoma-paraganglioma syndrome can be diagnosed reliably by an immunohistochemical procedure. SDHB, SDHC, and SDHD germline mutation testing is indicated only in patients with SDHB-negative tumours. SDHB immunohistochemistry on phaeochromocytomas and paragangliomas could improve the diagnosis of phaeochromocytoma-paraganglioma syndrome. FUNDING The Netherlands Organisation for Scientific Research, Dutch Cancer Society, Vanderes Foundation, Association pour la Recherche contre le Cancer, Institut National de la Santé et de la Recherche Médicale, and a PHRC grant COMETE 3 for the COMETE network.

Stress-Induced Norepinephrine Release in the Hypothalamic Paraventricular Nucleus and Pituitary-Adrenocortical and Sympathoadrenal Activity: In Vivo Microdialysis Studies

The hypothalamic-pituitary-adrenocortical (HPA) axis and the autonomic nervous system are major effector systems that serve to maintain homeostasis during exposure to stressors. In the past decade, interest in neurochemical regulation and in pathways controlling activation of the HPA axis has focused on catecholamines, which are present in high concentrations in specific brain areas--especially in the hypothalamus. The work described in this review has concentrated on the application of in vivo microdialysis in rat brain regions such as the paraventricular nucleus (PVN) of the hypothalamus, the central nucleus of the amygdala (ACE), the bed nucleus of the stria terminalis (BNST), and the posterolateral hypothalamus in order to examine aspects of catecholaminergic function and relationships between altered catecholaminergic function and the HPA axis and sympathoadrenal system activation in stress. Exposure of animals to immobilization (IMMO) markedly and rapidly increases rates of synthesis, release, and metabolism of norepinephrine (NE) in all the brain areas mentioned above and supports previous suggestions that in the PVN NE stimulates release of corticotropin-releasing hormone (CRH). The role of NE in the ACE and the BNST and most other areas possessing noradrenergic innervation remains unclear. Studies involving lower brainstem hemisections show that noradrenergic terminals in the PVN are derived mainly from medullary catecholaminergic groups rather than from the locus ceruleus, which is the main source of NE in the brain. Moreover, the medullary catecholaminergic groups contribute substantially to IMMO-induced noradrenergic activation in the PVN. Data obtained from adrenalectomized rats, with or without glucocorticoid replacement, and from hypercortisolemic rats suggest that glucocorticoids feedback to inhibit CRH release in the PVN, via attenuation of noradrenergic activation. Results from rats exposed to different stressors have indicated substantial differences among stressors in eliciting PVN noradrenergic responses as well as of responses of the HPA, sympathoneural, and adrenomedullary systems. Finally, involvement of other areas that participate in the regulation of the HPA axis such as the ACE, the BNST, and the hippocampus and the importance of stress-induced changes in expression of immediate early genes such as c-fos are discussed.

Clinical and molecular genetics of patients with the Carney-Stratakis syndrome and germline mutations of the genes coding for the succinate dehydrogenase subunits SDHB, SDHC, and SDHD.

Gastrointestinal stromal tumors (GISTs) may be caused by germline mutations of the KIT and platelet-derived growth factor receptor-α (PDGFRA) genes and treated by Imatinib mesylate (STI571) or other protein tyrosine kinase inhibitors. However, not all GISTs harbor these genetic defects and several do not respond to STI571 suggesting that other molecular mechanisms may be implicated in GIST pathogenesis. In a subset of patients with GISTs, the lesions are associated with paragangliomas; the condition is familial and transmitted as an autosomal-dominant trait. We investigated 11 patients with the dyad of ‘paraganglioma and gastric stromal sarcoma’; in eight (from seven unrelated families), the GISTs were caused by germline mutations of the genes encoding subunits B, C, or D (the SDHB, SDHC and SDHD genes, respectively). In this report, we present the molecular effects of these mutations on these genes and the clinical information on the patients. We conclude that succinate dehydrogenase deficiency may be the cause of a subgroup of GISTs and this offers a therapeutic target for GISTs that may not respond to STI571 and its analogs.

Superiority of Fluorodeoxyglucose Positron Emission Tomography to Other Functional Imaging Techniques in the Evaluation of Metastatic SDHB-Associated Pheochromocytoma and Paraganglioma

PURPOSE Germline mutations of the gene encoding subunit B of the mitochondrial enzyme succinate dehydrogenase (SDHB) predispose to malignant paraganglioma (PGL). Timely and accurate localization of these aggressive tumors is critical for guiding optimal treatment. Our aim is to evaluate the performance of functional imaging modalities in the detection of metastatic lesions of SDHB-associated PGL. PATIENTS AND METHODS Sensitivities for the detection of metastases were compared between [18F]fluorodopamine ([18F]FDA) and [18F]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET), iodine-123- (123I) and iodine-131 (131I) -metaiodobenzylguanidine (MIBG), 111In-pentetreotide, and Tc-99m-methylene diphosphonate bone scintigraphy in 30 patients with SDHB-associated PGL. Computed tomography (CT) and magnetic resonance imaging (MRI) served as standards of reference. RESULTS Twenty-nine of 30 patients had metastatic lesions. In two patients, obvious metastatic lesions on functional imaging were missed by CT and MRI. Sensitivity according to patient/body region was 80%/65% for 123I-MIBG and 88%/70% for [18F]FDA-PET. False-negative results on 123I-MIBG scintigraphy and/or [18F]FDA-PET were not predicted by genotype or biochemical phenotype. [18F]FDG-PET yielded a by patient/by body region sensitivity of 100%/97%. At least 90% of regions that were false negative on 123I-MIBG scintigraphy or [18F]FDA-PET were detected by [18F]FDG-PET. In two patients, 111In-pentetreotide scintigraphy detected liver lesions that were negative on other functional imaging modalities. Sensitivities were similar before and after chemotherapy or 131I-MIBG treatment, except for a trend toward lower post- (60%/41%) versus pretreatment (80%/65%) sensitivity of 123I-MIBG scintigraphy. CONCLUSION With a sensitivity approaching 100%, [18F]FDG-PET is the preferred functional imaging modality for staging and treatment monitoring of SDHB-related metastatic PGL.

Comparison of 18F-Fluoro-L-DOPA, 18F-Fluoro-Deoxyglucose, and 18F-Fluorodopamine PET and 123I-MIBG Scintigraphy in the Localization of Pheochromocytoma and Paraganglioma

CONTEXT Besides (123)I-metaiodobenzylguanidine (MIBG), positron emission tomography (PET) agents are available for the localization of paraganglioma (PGL), including (18)F-3,4-dihydroxyphenylalanine (DOPA), (18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG), and (18)F-fluorodopamine ((18)F-FDA). OBJECTIVE The objective of the study was to establish the optimal approach to the functional imaging of PGL and examine the link between genotype-specific tumor biology and imaging. DESIGN This was a prospective observational study. INTERVENTION There were no interventions. PATIENTS Fifty-two patients (28 males, 24 females, aged 46.8 +/- 14.2 yr): 20 with nonmetastatic PGL (11 adrenal), 28 with metastatic PGL (13 adrenal), and four in whom PGL was ruled out; 22 PGLs were of the succinate dehydrogenase subunit B (SDHB) genotype. MAIN OUTCOME MEASURES Sensitivity of (18)F-DOPA, (18)F-FDG, and (18)F-FDA PET, (123)I-MIBG scintigraphy, computed tomography (CT), and magnetic resonance imaging (MRI) for the localization of PGL were measured. RESULTS Sensitivities for localizing nonmetastatic PGL were 100% for CT and/or MRI, 81% for (18)F-DOPA PET, 88% for (18)F-FDG PET/CT, 78% for (18)F-FDA PET/CT, and 78% for (123)I-MIBG scintigraphy. For metastatic PGL, sensitivity in reference to CT/MRI was 45% for (18)F-DOPA PET, 74% for (18)F-FDG PET/CT, 76% for (18)F-FDA PET/CT, and 57% for (123)I-MIBG scintigraphy. In patients with SDHB metastatic PGL, (18)F-FDA and (18)F-FDG have a higher sensitivity (82 and 83%) than (123)I-MIBG (57%) and (18)F-DOPA (20%). CONCLUSIONS (18)F-FDA PET/CT is the preferred technique for the localization of the primary PGL and to rule out metastases. Second best, equal alternatives are (18)F-DOPA PET and (123)I-MIBG scintigraphy. For patients with known metastatic PGL, we recommend (18)F-FDA PET in patients with an unknown genotype, (18)F-FDG or (18)F-FDA PET in SDHB mutation carriers, and (18)F-DOPA or (18)F-FDA PET in non-SDHB patients.

Somatic HIF2A Gain-of-Function Mutations in Paraganglioma with Polycythemia

Hypoxia-inducible factors are transcription factors controlling energy, iron metabolism, erythropoiesis, and development. When these proteins are dysregulated, they contribute to tumorigenesis and cancer progression. However, mutations in genes encoding α subunits of hypoxia-inducible factors (HIF-α) have not previously been identified in any cancer. Here we report two novel somatic gain-of-function mutations in the gene encoding hypoxia-inducible factor 2α (HIF2A) in two patients, one presenting with paraganglioma and the other with paraganglioma and somatostatinoma, both of whom had polycythemia. The two mutations were associated with increased HIF-2α activity and increased protein half-life.