Malignant pheochromocytoma. Chromaffin granule transmitters and response to treatment

Main mechanisms and clinical implications of alterations in energy expenditure state among patients with pheochromocytoma and paraganglioma: A review

Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors with diverse clinical presentations. Alterations in energy expenditure state are commonly observed in patients with PPGL. However, the reported prevalence of hypermetabolism varies significantly and the underlying mechanisms and implications of this presentation have not been well elucidated. This review discusses and analyzes the factors that contribute to energy consumption. Elevated catecholamine levels in patients can significantly affect substance and energy metabolism. Additionally, changes in the activation of brown adipose tissue (BAT), inflammation, and the inherent energy demands of the tumor can contribute to increased resting energy expenditure (REE) and other energy metabolism indicators. The PPGL biomarker, chromogranin A (CgA), and its fragments also influence energy metabolism. Chronic hypermetabolic states may be detrimental to these patients, with surgical tumor removal remaining the primary therapeutic intervention. The high energy expenditure of PPGL has not received the attention it deserves, and an accurate assessment of energy metabolism is the cornerstone for an adequate understanding and treatment of the disease.

Biochemical Assessment of Pheochromocytoma and Paraganglioma

Pheochromocytoma and paraganglioma (PPGL) require prompt consideration and efficient diagnosis and treatment to minimize associated morbidity and mortality. Once considered, appropriate biochemical testing is key to diagnosis. Advances in understanding catecholamine metabolism have clarified why measurements of the O-methylated catecholamine metabolites rather than the catecholamines themselves are important for effective diagnosis. These metabolites, normetanephrine and metanephrine, produced respectively from norepinephrine and epinephrine, can be measured in plasma or urine, with choice according to available methods or presentation of patients. For patients with signs and symptoms of catecholamine excess, either test will invariably establish the diagnosis, whereas the plasma test provides higher sensitivity than urinary metanephrines for patients screened due to an incidentaloma or genetic predisposition, particularly for small tumors or in patients with an asymptomatic presentation. Additional measurements of plasma methoxytyramine can be important for some tumors, such as paragangliomas, and for surveillance of patients at risk of metastatic disease. Avoidance of false-positive test results is best achieved by plasma measurements with appropriate reference intervals and preanalytical precautions, including sampling blood in the fully supine position. Follow-up of positive results, including optimization of preanalytics for repeat tests or whether to proceed directly to anatomic imaging or confirmatory clonidine tests, depends on the test results, which can also suggest likely size, adrenal vs extra-adrenal location, underlying biology, or even metastatic involvement of a suspected tumor. Modern biochemical testing now makes diagnosis of PPGL relatively simple. Integration of artificial intelligence into the process should make it possible to fine-tune these advances.

Clinical and Pathological Tools for Predicting Recurrence and/or Metastasis in Patients with Pheochromocytoma and Paraganglioma

Pheochromocytomas and paragangliomas are endocrine tumors belonging to the family of neural crest cell-derived neoplasms. They have an extremely variable clinical course, characterized by a non-negligible percentage of relapse and/or metastasis after radical surgery. To date, there are no reliable methods to predict the metastatic potential of these neoplasms, despite several clinical, molecular, and histopathological factors that have been extensively studied in the literature as predictors of the recurrence and/or metastasis in these neoplasms with different performances and results. In this review, we aimed to discuss and analyze the most important clinical and histopathological tools for predicting recurrence risk in patients affected by pheochromocytomas or paragangliomas. Thus, we compared the main available predictive models, exploring their applications in stratifying patients’ risks. In conclusion, we underlined the importance of simple and validated tools to better define disease aggressiveness and establish tailored patients’ treatments and follow-ups.

Metastatic pheochromocytoma and paraganglioma: signs and symptoms related to catecholamine secretion

BACKGROUND

The presence or future development of metastatic pheochromocytomas or paragangliomas (mPPGLs) can be difficult to diagnose or predict at initial presentation. Since production of catecholamines from mPPGLs is different from non-metastatic tumors (non-mPPGLs), this study aimed to clarify whether presenting catecholamine-related signs and symptoms (cSS) might also differ.

METHODS

The study included 249 patients, 43 with mPPGL and 206 with non-mPPGL. Clinical data at the time of biochemical diagnosis (i.e. at entry into the study) were used to generate a cumulative score of cSS for each patient.

RESULTS

Patients with mPPGL were significantly younger (43.3 ± 14 vs. 48.9 ± 16.1 years) and included a lower proportion of females (39.5% vs. 60.7%) than patients with non-mPPGLs. Frequencies of signs and symptoms did not differ between the two groups. Patients with mPPGLs had lower (P < 0.001) urinary excretion of epinephrine (3.5 (IQR, 1.9-6.5) µg/day) than those with non-mPPGLs (19.1 (IQR, 4.3-70.2) µg/day). There was no difference in urinary excretion of norepinephrine. In patients with mPPGLs a high cSS score was associated with high urinary excretion of norepinephrine and normetanephrine. In contrast, in patients with non-mPPGLs, a high cSS was associated with high urinary excretion of epinephrine and metanephrine.

CONCLUSION

Although presenting signs and symptoms were associated with production of norepinephrine in patients with mPPGLs and of epinephrine in patients with non-mPPGLs, there were no differences in signs and symptoms between the two groups. Therefore, consideration of signs and symptoms does not appear helpful for distinguishing patients with and without mPPGLs.

Chromogranin A in a Cohort of Pheochromocytomas and Paragangliomas: Usefulness at Diagnosis and as an Early Biomarker of Recurrence

OBJECTIVE

To evaluate the usefulness of chromogranin A (CgA) in the management of patients with pheochromocytomas (PHEOs) and paragangliomas (PGLs).

METHODS

We retrospectively reviewed the charts of 132 patients with confirmed PHEOs/PGLs (PPGLs) followed at our medical center. CgA was measured in 80 patients at diagnosis. The exclusion criteria removed 19 of these patients. Five patients with relapses were also analyzed.

RESULTS

Our cohort of 61 patients included 34 PHEOs, 14 head and neck PGLs, and 13 thoracoabdominal PGLs. CgA levels were elevated in 53 of 61 patients (86.9%) at diagnosis: 33 of 34 (97.1%) PHEOs, 9 of 14 (64.3%) head and neck paragangliomas, and 11 of 13 (84.6%) thoracoabdominal paragangliomas. For 8 of 13 (61.5%) nonfunctional PPGLs (5 head and neck paragangliomas and 3 thoracoabdominal paragangliomas), increased CgA levels showed potential as a tumor marker during follow-up. Of 10 patients with malignant PPGLs, only 1 had normal CgA levels (10.0%). Among 54 patients with PPGLs who underwent genetic testing, elevated CgA levels were positive in 73.7% of patients carrying a germline genetic variant (pathogenic and of unknown significance) versus 91.4% of patients without a known germline variant. We also report 5 PPGL cases with increased CgA levels as the first detectable marker of tumoral recurrence or progression preceding other biochemical markers or imaging.

CONCLUSION

CgA is a sensitive marker for the diagnosis of PHEO (97.1%) and thoracoabdominal paraganglioma (84.6%). CgA may be useful in the follow-up of nonfunctional PGLs and may also play a complementary role in the early detection of recurrence in secreting PPGLs.

Diagnosis of a 09 cm pheochromocytoma mistaken to be an intramesenteric pancreatic tumor: Case report complying with the scare guidelines

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Pheochromocytoma’s case reports keep showing its diversity in clinical presentation, diagnosis methods treatment and follow up challenges.

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The diagnosis is basically simple by biomarkers testing, an imaging and challenging when biologically the tumor is silent.

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Functional imaging should be used to locate the tumor or its metastasis.

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Preoperative measures should be taken so no major preoperative complications and the main treatment is the tumor complete resection.

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The malignancy of the pheochromocytoma is not easy to be identified which imposes a lifetime follow up of these patients as metastasis were described even after 40 years after diagnosis.

Introduction

Pheochromocytoma is an adrenal medullary tumor of the chromaffin cells first described in 1886, remains an entity not fully discovered that case reports keep showing its diversity in clinical presentation, diagnosis methods treatment and follow up challenges.

Case presentation

We report the case of a 47 year old woman with complaining from abdominal pain and major weightless with a 09 cm tumor of the body of the pancreas viewed in imaging with no hormonal secretion but high levels of chromogranine A open surgery conducted that revealed the tumor to be located between the adrenal medulla and the Aorta misleading the team between an adrenal tumor or a zuckerkandl body tumor. The hemodynamic changes after manipulation of the tumor and the histopathology confirming the diagnosis of pheochromocytoma. Our main surprise was the aspect of the tumor bombing in the peritoneal cavity firstly thought to be mesenteric tumor; and the stability of the patient with no premedication until the tumor had been manipulated, enlarging the hypothesis about catecholamine secretion of these tumor.

Discussion

The diagnosis is basically simple when the tumor expresses its catecholamines by biomarkers testing, an imaging. Functional imaging should be used to locate the tumor or its metastasis, the sequence of testing or imaging can vary either it’s a symptomatic tumor or an incidentaloma. Preoperative measures should be taken so no major preoperative complications and the main treatment is the tumor complete resection

Conclusion

The malignancy of the pheochromocytoma is no near to be reliably identified which imposes a lifetime follow up of these patients as for metastasis were described even after 40 years after diagnosis.

Metastatic pheochromocytoma to the pancreas diagnosed by endoscopic ultrasound-guided fine needle aspiration: A case report and review of literature

Pancreatic pheochromocytomas are rare and typically diagnosed by local resection. We present the first reported case of metastatic pheochromocytoma to the pancreas diagnosed by endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) and cytology. A 67-year-old female presented with 2 to 3 months of abdominal pain. A CT scan showed a large mass in the head of the pancreas engulfing the superior mesentery artery and vein, along with a large mass in the left adrenal gland. An EUS-FNA was performed on the pancreatic mass with a 22-gauge needle, yielding an adequate sample. Papanicolaou stain, Diff-Quik, and cell block showed loosely cohesive clustered tumor cells and singly dispersed pleomorphic naked tumor nuclei with anisonucleosis and cytoplasmic vacuolization. Tumor cells stained positive for synaptophysin, chromogranin A, and CD56 and negative for CK AE1/3 and CK AE1/3-CAM5.2 cytokeratin cocktail. Because of cytokeratin negativity, diffusely positive neuroendocrine markers, and the presence of an adrenal mass, a metastatic malignant pheochromocytoma was suspected. Additional testing showed elevations in plasma metanephrines and normetanephrines, urine metanephrine-to-creatinine and normetanephrine-to-creatinine ratios, and serum chromogranin A. An iodine¹²³ -metaiodobenzylguanidine (MIBG) scan was obtained, which showed significantly increased MIBG uptake in the left adrenal lesion. A diagnosis of metastatic malignant pheochromocytoma was made. Surgical oncology was consulted, who recommended against resection of the adrenal mass in favor of outpatient management. Metastatic pheochromocytoma to the pancreas are rare tumors that may yield diagnostic material by EUS-FNA with a 22-gauge needle.

Predictors of recurrence of pheochromocytoma and paraganglioma: a multicenter study in Piedmont, Italy

The available data on the natural history of pheochromocytomas and paragangliomas after radical surgery are heterogeneous and discordant. The aim of our retrospective multicenter study was to find predictors of recurrence in patients with pheochromocytomas and sympathetic paragangliomas submitted to radical surgery in Piedmont (a region in northwest Italy). We collected data from 242 patients diagnosed between 1990 and 2016. Forty-two patients (17.4%) had disease recurrence. Multivariate analysis showed that genetic mutation (HR = 3.62; 95% CI 1.44-9.13; p = 0.006), younger age (HR = 0.97; 95% CI 0.95-0.99; p = 0.031) and larger tumor size (HR = 1.01; 95% CI 1.00-1.02; p = 0.015) were independently associated with a higher recurrence risk of pheochromocytoma and paraganglioma; in pheochromocytomas, genetic mutation (HR = 3.4; 95% CI 1.00-11.48; p = 0.049), younger age (HR = 0.97; 95% CI 0.94-0.99; p = 0.02), higher tumor size (HR = 1.01; 95% CI 1.00-1.03; p = 0.043) and PASS value (HR = 1.16; 95% CI 1.03-1.3; p = 0.011) were associated with recurrence. Moreover, tumor size was the only predictor of metastatic pheochromocytoma and paraganglioma (HR = 4.6; 95% CI 1.4-15.0; p = 0.012); tumor size (HR = 3.93; 95% CI 1.2-16.4; p = 0.026) and PASS value (HR = 1.27; 95% CI 1.06-1.53; p = 0.007) were predictors of metastatic pheochromocytoma. In conclusion, our findings suggest that the recurrence of pheochromocytoma and sympathetic paraganglioma develops more frequently in younger subjects, patients with a family history of chromaffin tissue neoplasms, mutations in susceptibility genes, larger tumors and higher values of PASS. We recommend genetic testing in all patients with PPGL and strict follow-up at least on an annual basis.

High Plasma Levels of Human Chromogranin a and Adrenomedullin in Patients with Pheochromocytoma

Aims and background

The aim of our study was to investigate the plasma chromogranin A (CgA) and adrenomedullin (AM) levels in patients with pheochromocytomas.

Methods and study design

We collected blood samples for measurement of plasma CgA and AM in 21 patients with pheochromocytomas, 43 healthy subjects and 26 patients with solid non-functioning adrenocortical adenomas. In 11 patients with pheochromocytomas plasma CgA and AM were measured again four weeks after tumor removal. CgA and AM were measured by means of a novel solid-phase two-site immunoradiometric assay based on monoclonal antibodies (CgA-RIA CT, CIS bio international) and by a specific radioimmunoassay (RIA, Phoenix Pharm. Inc.), respectively.

Results

The mean plasma CgA level (±SD) in patients with pheochromocytomas (204 ± 147.9 ng/mL) was significantly higher (P <0.001) than that in healthy subjects (41.6 ± 10.7 ng/mL) and in patients with non-functioning adrenocortical adenomas (47.3 ± 17.6 ng/mL). The mean plasma AM concentration (±SD) in patients with pheochromocytomas (27.5 ± 10.4 pg/mL) was significantly higher (P <0.001) than that in HS (13.8 ± 4.5 pg/mL) and in patients with non-functioning adrenocortical adenomas (16.6 ± 7.3 pg/mL). Plasma CgA levels correlated with plasma AM levels (r = 0.501; P <0.02) and with plasma metanephrine levels (r = 0.738; P <0.0001) in patients with pheochromocytomas. In 11 patients with pheochromocytomas plasma CgA and AM concentrations significantly decreased after tumor removal (P <0.001 for both). Circulating CgA and AM had a sensitivity of 76.2% and 81%, a specificity of 97.7% and 90.7%, and an accuracy of 91% and 88%, respectively.

Conclusion

This study demonstrates that circulating CgA and AM levels are increased in pheochromocytoma patients compared with healthy subjects and patients with non-functioning adrenocortical adenomas. Moreover, at the time of diagnosis plasma CgA levels correlated with plasma AM levels and with plasma metanephrine levels in all patients with pheochromocytomas. In conclusion, plasma CgA and AM concentrations may represent additional biochemical parameters for clinical monitoring of patients with pheochromocytomas.

European Society of Endocrinology Clinical Practice Guideline for long-term follow-up of patients operated on for a phaeochromocytoma or a paraganglioma

Phaeochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumours. Standard treatment is surgical resection. Following complete resection of the primary tumour, patients with PPGL are at risk of developing new tumoural events. The present guideline aims to propose standardised clinical care of long-term follow-up in patients operated on for a PPGL. The guideline has been developed by The European Society of Endocrinology and based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) principles. We performed a systematic review of the literature and analysed the European Network for the Study of Adrenal Tumours (ENS@T) database. The risk of new events persisted in the long term and was higher for patients with genetic or syndromic diseases. Follow-up in the published cohorts and in the ENS@T database was neither standardised nor exhaustive, resulting in a risk of follow-up bias and in low statistical power beyond 10 years after complete surgery. To inform patients and care providers in this context of low-quality evidence, the Guideline Working Group therefore prepared recommendations on the basis of expert consensus. Key recommendations are the following: we recommend that all patients with PPGL be considered for genetic testing; we recommend assaying plasma or urinary metanephrines every year to screen for local or metastatic recurrences or new tumours; and we suggest follow-up for at least 10 years in all patients operated on for a PPGL. High-risk patients (young patients and those with a genetic disease, a large tumour and/or a paraganglioma) should be offered lifelong annual follow-up.

A novel diagnostic method of Raman spectroscopy for malignant pheochromocytoma/paraganglioma

Raman spectroscopy, a potential tool in diagnosis of malignant pheochromocytoma/paraganglioma.

Treatment of malignant phaeochromocytoma with a combination of cyclophosphamide, vincristine and dacarbazine: own experience and overview of the contemporary literature

OBJECTIVE

Malignant phaeochromocytomas are rare and highly aggressive tumours. This retrospective study evaluated the outcome of combined chemotherapy with cyclophosphamide, vincristine and dacarbazine (also known as CVD regimen).

METHODS

Patients with histologically and radiologically confirmed malignant phaeochromocytoma who were treated with the CVD regimen for progressive disease were retrospectively identified from chart review. Treatment cycles were usually repeated at 21-day intervals, with cyclophosphamide (750 mg/m(2) ), vincristine (1·4 mg/m(2) ) and dacarbazine (600 mg/m(2) ) on day 1, and dacarbazine only (600 mg/m(2) ) on day 2. The main outcome measures were best response during treatment and progression-free survival.

RESULTS

Eight patients (4 males; median age 55·5 (range 31-77) years) with progressive disease underwent a median of 6 (range 3-11) cycles. Best treatment responses were as follows: partial response, n = 2 (25%); stable disease, n = 3 (38%); and progressive disease, n = 3 (38%). The median progression-free survival was 5·4 (range 2·5-26·8) months. After the initial administration of 6 cycles, two patients received a second course of chemotherapy with another 6 cycles after new progressive disease had been detected. Subsequently, these patients were progression-free for another 6·0 and 6·4 months. Mild gastrointestinal symptoms and fatigue were the most common adverse events.

CONCLUSION

Although objective tumour response rates were lower than previously reported in small series, the CVD regimen allowed disease stabilization for a substantial period of time and may therefore be considered as a treatment option in advanced stages. To improve disease outcome, however, new therapeutic approaches and larger multicentre studies are needed.

Clinical management of paragangliomas

Paragangliomas (PGLs) are rare vascular, neuroendocrine tumors of paraganglia, which are associated with either sympathetic tissue in adrenal (pheochromocytomas (PCCs)) and extraadrenal (sympathetic paraganglioma (sPGLs)) locations or parasympathetic tissue of the head and neck paragangliomas (HNPGLs). As HNPGLs are usually benign and most tumors grow slowly, a wait-and-scan policy is often advised. However, their location in the close proximity to cranial nerves and vasculature may result in considerable morbidity due to compression or infiltration of the adjacent structures, necessitating balanced decisions between a wait-and-see policy and active treatment. The main treatment options for HNPGL are surgery and radiotherapy. In contrast to HNPGLs, the majority of sPGL/PCCs produces catecholamines, in advanced cases resulting in typical symptoms and signs such as palpitations, headache, diaphoresis, and hypertension. The state-of-the-art diagnosis and localization of sPGL/PCCs are based on measurement of plasma and/or 24-h urinary excretion of (fractionated) metanephrines and methoxytyramine (MT). sPGL/PCCs can subsequently be localized by anatomical (computed tomography and/or magnetic resonance imaging) and functional imaging studies (123I-metaiodobenzylguanidine-scintigraphy, 111In-pentetreotide scintigraphy, or positron emission tomography with radiolabeled dopamine or dihydroxyphenylalanine). Although most PGL/PCCs are benign, factors such as genetic background, tumor size, tumor location, and high MT levels are associated with higher rates of metastatic disease. Surgery is the only curative treatment. Treatment options for patients with metastatic disease are limited. PGL/PCCs have a strong genetic background, with at least one-third of all cases linked with germline mutations in 11 susceptibility genes. As genetic testing becomes more widely available, the diagnosis of PGL/PCCs will be made earlier due to routine screening of at-risk patients. Early detection of a familial PGL allows early detection of potentially malignant PGLs and early surgical treatment, reducing the complication rates of this operation.

Chemotherapy with cyclophosphamide, vincristine and dacarbazine for malignant paraganglioma and pheochromocytoma: systematic review and meta-analysis

BACKGROUND

Chemotherapy with cyclophosphamide, vincristine and dacarbazine (CVD) can be used for palliative treatment of malignant pheochromocytoma and paraganglioma. However, the precise effect of this chemotherapeutic regimen on tumour volume is unclear. The main objective of this study was to perform a systematic review and meta-analysis assessing the effect of chemotherapy with CVD on tumour volume in patients with malignant paraganglioma/pheochromocytoma.

METHODS

A literature search was performed in October 2013 to identify potentially relevant studies. Main outcomes were the pooled percentages of complete response, partial response and stable disease after chemotherapy with CVD. A meta-analysis was performed with an exact likelihood approach using a logistic regression. Pooled percentages with 95% confidence intervals (CI) were reported.

RESULTS

Four studies concerning a total of 50 patients with malignant paraganglioma/pheochromocytoma reported on treatment with a combination of CVD chemotherapy. A meta-analysis of the effect of chemotherapy on tumour volume showed pooled percentages of complete response, partial response and stable disease of, respectively, 4% (95% CI: 1%-15%), 37%(95% CI: 25%-51%) and 14% (95% CI: 7%-27%). Only two studies concerning a total of 35 patients assessed the response on catecholamine excess; pooled percentages for complete, partial and stable hormonal response were 14% (95% CI: 6%-30%), 40% (95% CI: 25%-57%) and 20% (95% CI: 10%-36%), respectively. Duration of response was also reported in only two studies with a median duration of response of 20 months and 40 months.

CONCLUSIONS

Data on the effects of a combination of CVD chemotherapy on malignant paraganglioma/pheochromocytoma suggest that a partial response concerning tumour volume can be achieved in about 37% of patients and a partial response on catecholamine excess in about 40% of patients. However, in the included studies, the protocol when to initiate treatment was not well described. Therefore, it cannot be excluded that the reported effect of chemotherapy on tumour volume reflects the natural course of the disease, at least partially.

Malignant Pelvic Pheochromocytoma Presenting as NonFunctioning Kidney and Accelerated Hypertension: A Rare Presentation

Paragangliomas are neuroendocrine tumors that arise from sympathetic nerve ganglia. They can develop anywhere from the neck to the pelvis, but are most commonly found in the abdomen, particularly at the aortic bifurcation or in the periaortic region. Malignant paragangliomas account for 29-40% of cases. We report a case of 36-year hypertensive female presented with and right flank pain and accelerated hypertension. On evaluation she was diagnosed to have non unctioning kidney due to malignant pelvic paraganglioma with right ureteric encasement. We believe our case is one of the first reported in literature as rare presentation of malignant paraganglioma presenting as nonfunctioning kidney and accelerated hypertension.

Current and future treatments for malignant pheochromocytoma and sympathetic paraganglioma

Pheochromocytomas (PHs) and sympathetic paragangliomas (SPGs) are rare neuroendocrine tumors. Approximately 17 % of these tumors are malignant, but because no molecular or histologic markers for malignancy exist, patients are often diagnosed with malignant PHs or SPGs after unresectable disease has formed. Patients with progressive metastatic tumors and overwhelming symptoms are currently treated with systemic chemotherapy and radiopharmaceutical agents such as metaiodobenzylguanidine. These therapies lead to partial radiographic response, disease stabilization, and symptomatic improvement in approximately 40 % of patients, and systemic chemotherapy is associated with a modest improvement in overall survival duration. However, over the past decade, substantial progress has been made in clinical, biochemical, and radiographic diagnosis of PHs and SPGs. Approximately 50 % of patients with malignant PHs and SPGs have been found to carry hereditary germline mutations in the succinate dehydrogenase subunit B gene (SDHB), and anti-angiogenic agents such as sunitinib have been found to potentially play a role in the treatment of malignant disease, especially in patients with SDHB mutations. In some patients, treatment with sunitinib has been associated with partial radiographic response, disease stabilization, decreased fluorodeoxyglucose uptake on positron emission tomography, and improved blood pressure control. These findings have led to the development of prospective clinical trials of new targeted therapies for metastatic disease. Here, we provide an updated review of the clinical and genetic predictors of malignant disease, radiographic diagnosis of malignant disease, and information from the most relevant studies of systemic therapies, as well as proposed treatment guidelines for patients with metastatic or potentially malignant PHs and SPGs.

Molecular and therapeutic advances in the diagnosis and management of malignant pheochromocytomas and paragangliomas

Pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare catecholamine-secreting tumors derived from chromaffin cells originating in the neural crest. These tumors represent a significant diagnostic and therapeutic challenge because the diagnosis of malignancy is frequently made in retrospect by the development of metastatic or recurrent disease. Complete surgical resection offers the only potential for cure; however, recurrence can occur even after apparently successful resection of the primary tumor. The prognosis for malignant disease is poor because traditional treatment modalities have been limited. The last decade has witnessed exciting discoveries in the study of PCCs and PGLs; advances in molecular genetics have uncovered hereditary and germline mutations of at least 10 genes that contribute to the development of these tumors, and increasing knowledge of genotype-phenotype interactions has facilitated more accurate determination of malignant potential. Elucidating the molecular mechanisms responsible for malignant transformation in these tumors has opened avenues of investigation into targeted therapeutics that show promising results. There have also been significant advances in functional and radiological imaging and in the surgical approach to adrenalectomy, which remains the mainstay of treatment for PCC. In this review, we discuss the currently available diagnostic and therapeutic options for patients with malignant PCCs and PGLs and detail the molecular rationale and clinical evidence for novel and emerging diagnostic and therapeutic strategies.

Malignant abdominal paraganglioma presenting as a giant intra-peritoneal mass

INTRODUCTION

Paraganglioma is a malignant tumor that arises from the extra adrenal paraganglionic cells of the sympathetic or parasympathetic systems. Herein, we present a case of abdominal mass of unknown histology that underwent a very difficult surgical mass resection. Its final histologic diagnosis was non-functional paraganglioma that was presented as a huge intra-peritoneal mass.

PRESENTATION OF CASE

The patient was a 55-year-old Iranian lady who referred to our center with a giant abdominal mass. Fine needle aspiration (FNA) biopsy showed undifferentiated carcinoma. After laparotomy for mass resection pathology evaluation revealed; malignant paraganglioma, non-metastatic type. Further post-operative patients evaluations showed that the tumor was sporadic in nature and the subsequent patient's natural history was uneventful.

DISCUSSION

Pathologic evaluations have key roles in the exact diagnosis of abdominal masses with unidentified sources. For the paragangliomas, all of them should be regarded malignant until proved otherwise. However, combined use of biochemical markers, immunohistochemical techniques (IHC), and genetic analysis have key roles in the diagnosis and treatment of paragangliomas. Additionally, surgical removal is the proved curative way of paraganglioma treatment.

CONCLUSION

Asymptomatic intra-peritoneal paraganglioma is very rare, especially its malignant variety. This case emphasizes that full pathologic investigation would reveal the exact nature of idiopathic abdominal masses, especially in the state of absence of typical clinical and para-clinical symptoms.

Updated and new perspectives on diagnosis, prognosis, and therapy of malignant pheochromocytoma/paraganglioma

Malignant pheochromocytomas/paragangliomas are rare tumors with a poor prognosis. Malignancy is diagnosed by the development of metastases as evidenced by recurrences in sites normally devoid of chromaffin tissue. Histopathological, biochemical, molecular and genetic markers offer only information on potential risk of metastatic spread. Large size, extraadrenal location, dopamine secretion, SDHB mutations, a PASS score higher than 6, a high Ki-67 index are indexes for potential malignancy. Metastases can be present at first diagnosis or occur years after primary surgery. Measurement of plasma and/or urinary metanephrine, normetanephrine and metoxytyramine are recommended for biochemical diagnosis. Anatomical and functional imaging using different radionuclides are necessary for localization of tumor and metastases. Metastatic pheochromocytomas/paragangliomas is incurable. When possible, surgical debulking of primary tumor is recommended as well as surgical or radiosurgical removal of metastases. I-131-MIBG radiotherapy is the treatment of choice although results are limited. Chemotherapy is reserved to more advanced disease stages. Recent genetic studies have highlighted the main pathways involved in pheochromocytomas/paragangliomas pathogenesis thus suggesting the use of targeted therapy which, nevertheless, has still to be validated. Large cooperative studies on tissue specimens and clinical trials in large cohorts of patients are necessary to achieve better therapeutic tools and improve patient prognosis.

Pheochromocytoma and paraganglioma: understanding the complexities of the genetic background

Pheochromocytomas and paragangliomas (PCC/PGL) are tumors derived from the adrenal medulla or extra-adrenal ganglia, respectively. They are rare and often benign tumors that are associated with high morbidity and mortality due to mass effect and high circulating catecholamines. Although most PCCs and PGLs are thought to be sporadic, over one third are associated with 10 known susceptibility genes. Mutations in three genes causing well characterized tumor syndromes are associated with an increased risk of developing PCCs and PGLs, including VHL (von Hippel-Lindau disease), NF1 (Neurofibromatosis Type 1), and RET (Multiple Endocrine Neoplasia Type 2). Mutations in any of the succinate dehydrogenase (SDH) complex subunit genes (SDHA, SDHB, SDHC, SDHD) can lead to PCCs and PGLs with variable penetrance, as can mutations in the subunit cofactor, SDHAF2. Recently, two additional genes have been identified, TMEM127 and MAX. Although these tumors are rare in the general population, occurring in two to eight per million people, they are more commonly associated with an inherited mutation than any other cancer type. This review summarizes the known germline and somatic mutations leading to the development of PCC and PGL, as well as biochemical profiling for PCCs/PGLs and screening of mutation carriers.

Diagnostic tests and biomarkers for pheochromocytoma and extra-adrenal paraganglioma: from routine laboratory methods to disease stratification

The laboratory workup of patients with pheochromocytoma and extra-adrenal paraganglioma (PPGLs) has traditionally focused on biochemical measurements of tumor secretory products or their metabolites, with ultimate diagnosis resting on routine histopathology and immunohistochemistry. While such testing remains important, the needs to distinguish potentially metastatic from benign tumors and to identify tumors with a hereditary basis have stimulated searches for additional means to stratify patients according to risk of metastasis or presence of a particular mutation. Biomarkers based on traditional biochemical tests, such as profiles of catecholamine metabolites and granin-derived peptides, provide utility for both purposes, while novel biomarkers are being identified by proteomic and transcriptomic studies, the latter including microRNA expression profiling. Histopathological scoring methods for predicting metastatic potential, such as the Pheochromocytoma of the Adrenal Gland Scaled Score (PASS), are limited by poor interobserver concordance, discrepant results between studies and incomplete knowledge of how scores relate to genotype. Immunohistochemical staining for succinate dehydrogenase (SDH) subunit B to triage patients for genetic testing of SDH subunit genes illustrates the growing importance of pathology as an adjunct to genetic testing for disease stratification. Although considerable effort has been expended on microarray-based platforms to identify biomarkers of malignancy, as yet, none of those proposed have been demonstrated to reliably discriminate malignant from benign disease any better than the PASS. Because of the heterogeneity of PPGLs and variable time between first appearance of tumors and identification of metastases, any prospective study to establish prognostic efficacy requires large numbers of patients and extended follow-up.

Pheochromocytomas and paragangliomas: assessment of malignant potential

Pheochromocytomas and paragangliomas (PPGLs) are rare catecholamine-secreting tumors which arise from the adrenal glands or sympathetic neuronal tissue. Malignant transformation of these tumors occurs in a significant proportion and may therefore lower overall survival rates. In patients with PPGLs it is impossible to identify malignant disease without the presence of metastatic disease, something which can occur as long as 20 years after initial surgery. Early identification of malignant disease would necessitate a more aggressive treatment approach, something which may result in better disease outcome. We have therefore reviewed possible predictors of malignancy and current developments in order to help clinicians to swiftly assess malignant potential in patients with PPGLs. Currently, there is no absolute marker which can objectively reflect malignant potential. Tumor size is the most reliable predictor and should therefore be used as the baseline characteristic. The combination of various clinical markers (extra-adrenal disease and post-operative hypertension), biochemical markers (high dopamine, high norepinephrine and epinephrine to total catecholamine ratio) and/or histological markers (SNAIL, microRNAs and/or microarray results) can raise or lower the suspicion of malignancy. Furthermore, we discuss how clinical markers may affect biochemical results linked to malignancy, how biochemical results may distinguish hereditary syndromes, the role of imaging in determining malignant potential and tumor detection, and recent results of proposed histological markers.

Malignant pheochromocytomas and paragangliomas: a diagnostic challenge

INTRODUCTION

Malignant pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare disorders arising from the adrenal gland, from the glomera along parasympathetic nerves or from paraganglia along the sympathetic trunk. According to the WHO classification, malignancy of PCCs and PGLs is defined by the presence of metastases at non-chromaffin sites distant from that of the primary tumor and not by local invasion. The overall prognosis of metastasized PCCs/PGLs is poor. Surgery offers currently the only change of cure. Preferably, the discrimination between malignant and benign PCCs/PGLs should be made preoperatively.

METHODS

This review summarizes our current knowledge on how benign and malignant tumors can be distinguished.

CONCLUSION

Due to the rarity of malignant PCCs/PGLs and the obvious difficulties in distinguishing benign and malignant PCCs/PGLs, any patient with a PCC/PGL should be treated in a specialized center where a multidisciplinary setting with specialized teams consisting of radiologists, endocrinologist, oncologists, pathologists and surgeons is available. This would also facilitate future studies to address the existing diagnostic and/or therapeutic obstacles.

Plasma methoxytyramine: a novel biomarker of metastatic pheochromocytoma and paraganglioma in relation to established risk factors of tumour size, location and SDHB mutation status

BACKGROUND

There are currently no reliable biomarkers for malignant pheochromocytomas and paragangliomas (PPGLs). This study examined whether measurements of catecholamines and their metabolites might offer utility for this purpose.

METHODS

Subjects included 365 patients with PPGLs, including 105 with metastases, and a reference population of 846 without the tumour. Eighteen catecholamine-related analytes were examined in relation to tumour location, size and mutations of succinate dehydrogenase subunit B (SDHB).

RESULTS

Receiver-operating characteristic curves indicated that plasma methoxytyramine, the O-methylated metabolite of dopamine, provided the most accurate biomarker for discriminating patients with and without metastases. Plasma methoxytyramine was 4.7-fold higher in patients with than without metastases, a difference independent of tumour burden and the associated 1.6- to 1.8-fold higher concentrations of norepinephrine and normetanephrine. Increased plasma methoxytyramine was associated with SDHB mutations and extra-adrenal disease, but was also present in patients with metastases without SDHB mutations or those with metastases secondary to adrenal tumours. High risk of malignancy associated with SDHB mutations reflected large size and extra-adrenal locations of tumours, both independent predictors of metastatic disease. A plasma methoxytyramine above 0.2nmol/L or a tumour diameter above 5cm indicated increased likelihood of metastatic spread, particularly when associated with an extra-adrenal location.

CONCLUSION

Plasma methoxytyramine is a novel biomarker for metastatic PPGLs that together with SDHB mutation status, tumour size and location provide useful information to assess the likelihood of malignancy and manage affected patients.

Phaeochromocytoma: a catecholamine and oxidative stress disorder

The WHO classification of endocrine tumors defines pheochromocytoma as a tumor arising from chromaffin cells in the adrenal medulla - an intra-adrenal paraganglioma. Closely related tumors of extra-adrenal sympathetic and parasympathetic paraganglia are classified as extra-adrenal paragangliomas. Almost all pheochromocytomas and paragangliomas produce catecholamines. The concentrations of catecholamines in pheochromocytoma tissues are enormous, potentially creating a volcano that can erupt at any time. Significant eruptions result in catecholamine storms called "attacks" or "spells". Acute catecholamine crisis can strike unexpectedly, leaving traumatic memories of acute medical disaster that champions any intensive care unit. A very well-defined genotype-biochemical phenotype relationship exists, guiding proper and cost-effective genetic testing of patients with these tumors. Currently, the production of norepinephrine and epinephrine is optimally assessed by the measurement of their O-methylated metabolites, normetanephrine or metanephrine, respectively. Dopamine is a minor component, but some paragangliomas produce only this catecholamine or this together with norepinephrine. Methoxytyramine, the O-methylated metabolite of dopamine, is the best biochemical marker of these tumors. In those patients with equivocal biochemical results, a modified clonidine suppression test coupled with the measurement of plasma normetanephrine has recently been introduced. In addition to differences in catecholamine enzyme expression, the presence of either constitutive or regulated secretory pathways contributes further to the very unique mutation-dependent catecholamine production and release, resulting in various clinical presentations. Oxidative stress results from a significant imbalance between levels of prooxidants, generated during oxidative phosphorylation, and antioxidants. The gradual accumulation of prooxidants due to metabolic oxidative stress results in proto-oncogene activation, tumor suppressor gene inactivation, DNA damage, and genomic instability. Since the mitochondria serves as the main source of prooxidants, any mitochondrial impairment leads to severe oxidative stress, a major outcome of which is tumor development. In terms of cancer pathogenesis, pheochromocytomas and paragangliomas represent tumors where the oxidative phosphorylation defect due to the mutation of succinate dehydrogenase is the cause, not a consequence, of tumor development. Any succinate dehydrogenase pathogenic mutation results in the shift from oxidative phosphorylation to aerobic glycolysis in the cytoplasm (also called anaerobic glycolysis if hypoxia is the main cause of such a shift). This phenomenon, also called the Warburg effect, is well demonstrated by a positive [18F]-fluorodeoxyglycose positron emission tomography scan. Microarray studies, genome-wide association studies, proteomics and protein arrays, metabolomics, transcriptomics, and bioinformatics approaches will remain powerful tools to further uncover the pathogenesis of these tumors and their unique markers, with the ultimate goal to introduce new therapeutic options for those with metastatic or malignant pheochromocytoma and paraganglioma. Soon oxidative stress will be tightly linked to a multistep cancer process in which the mutation of various genes (perhaps in a logistic way) ultimately results in uncontrolled growth, proliferation, and metastatic potential of practically any cell. Targeting the mTORC, IGF-1, HIF and other pathways, topoisomerases, protein degradation by proteosomes, balancing the activity of protein kinases and phosphatases or even synchronizing the cell cycle before any exposure to any kind of therapy will soon become a reality. Facing such a reality today will favor our chances to "beat" this disease tomorrow.

Changing paradigms in the treatment of malignant pheochromocytoma

BACKGROUND

Pheochromocytomas and paragangliomas are intra- and extra-adrenal neoplasms that are rarely malignant. The treatment of those that are malignant has remained a challenge because little was known about the molecular pathways involved in its malignant transformation. Recently, however, the genetic and molecular changes involved in malignant pheochromocytoma have come to be understood.

METHODS

The authors review the recent literature about the changing treatment options for malignant pheochromocytomas and paragangliomas.

RESULTS

Traditional treatments for malignant pheochromocytoma remain unsuccessful. With the advances made in genomics and proteomics, novel pathways in pheochromocytoma carcinogenesis are becoming the targets of new treatment strategies and show promising results.

CONCLUSIONS

Although several studies and clinical trials show great promise for improving the treatment of pheochromocytomas and paragangliomas, the hope is that future collaborative efforts will allow for prospective clinical trials using an evidenced-based approach.

Chromogranin A: a novel factor acting at the cross road between the neuroendocrine and the cardiovascular systems

Chromogranin A (CHGA) is a secretory protein stored in and released from neurons and cells of the diffuse neuroendocrine system. Cells of the adrenal medulla and adrenergic terminals are a main source of CHGA but also myocardial cells produce it under stress conditions. After secretion, CHGA is cleaved into several biologically active fragments, including vasostatins and catestatin. CHGA and its proteolytic peptides exert a broad spectrum of activities on the cardiovascular system. They act on blood pressure by controlling the vascular tone and the cardiac inotropic and chronotropic function. CHGA revealed to be a sensitive marker of myocardial dysfunction, with a high predictive power of morbidity and mortality in heart failure and ischemic heart disease. In addition, CHGA has been involved in the control of sustained endothelial inflammation and has been shown to be a good marker of persistent vascular inflammation in rheumatologic disorders affecting vessels.

Malignant pheochromocytoma: predictive factors of malignancy and clinical course in 16 patients at a single tertiary medical center

Metastases appear in approximately 10% of patients with pheochromocytoma. There is no predictive marker of malignancy. The aim is to describe clinical course of patients with malignant pheochromocytoma and to identify predictive features of malignancy. The method involves retrospective analysis of patients files diagnosed with malignant pheochromocytoma at our institution between January 1, 1980 and December 31, 2008. We identified 16 patients with malignant pheochromocytoma. There were more men than women (10/6). Mean age of patients at time of diagnosis was 37.75-year-old. Time of occurrence of metastases ranged from 0 to 22 years after first diagnosis of pheochromocytoma. The mean size of the primary tumor was 12.1 cm. High levels of chromogranin A at the time of diagnosis were associated with the presence of metastases. The pheochromocytoma of the adrenal gland scoring scale (PASS) histological evaluation in adrenal primary tumors was above four in all cases but one. All patients had initial surgery, followed in most cases by palliative therapy: chemotherapy (streptozocin, cyclophosphamide-vincristine-dacarbazine, thalidomide, imatinib, everolimus) or (131)I-MIBG; only the latter had replicable encouraging response evaluation criteria in solid tumor response rates. We observed a 10-year survival rate of 50% after initial diagnosis of pheochromocytoma, and 25% after diagnosis of metastasis. Metastasis can occur very late after the initial diagnosis of pheochromocytoma. High chromogranin A levels may be associated with the presence of metastases and poor prognosis. Histological adrenal PASS higher than 4 appears to be suggestive of malignancy. The best therapeutic approach remains to be established.

Plasma chromogranin A levels are increased in a small portion of patients with hereditary head and neck paragangliomas

CONTEXT

The majority of patients with head and neck paragangliomas (HNPGL) have biochemically silent tumours. Chromogranin A (CgA) is a tumour marker for neuroendocrine tumours.

OBJECTIVE

To assess the role of CgA as a tumour marker in patients with hereditary HNPGL.

PATIENTS AND METHODS

We included 95 consecutive patients with hereditary HNPGL for screening of plasma CgA levels and catecholamine excess by measurement of 24-h urinary excretion of (nor)metanephrine, (nor)adrenaline, VMA, dopamine and 3-methoxytyramine. In all patients with catecholamine excess, abdominal/intrathoracic paragangliomas were excluded by (123) I-MIBG scintigraphy, MRI and/or CT.

RESULTS

Plasma CgA levels were increased in only 15 of 95 patients (16%). Thirty-three of the 95 patients (35%) had increased urinary excretion rates of catecholamines. Six of these 33 patients (18%) had increased plasma CgA levels. Nine of the 62 patients (15%) with a biochemically silent tumour, i.e. no increased urinary excretion of catecholamines or their metabolites, had increased CgA levels. Increased plasma CgA levels were positively correlated with urinary excretion rates of noradrenaline (r = 0·68, P = 0·005) and normetanephrine (r = 0·68, P = 0·005). There was a positive correlation between maximal HNPGL diameter and plasma CgA levels in the 57 patients with a single HNPGL (r = 0·57, P = 0·001).

CONCLUSIONS

Plasma CgA levels are increased in only a small portion of patients with hereditary HNPGL and have limited additional value to the combination of radiological and routine biochemical assessment of patients with HNPGL. Increased plasma CgA levels are associated with increased noradrenergic activity and tumour size in patients with a single HNPGL.

Malignant pheochromocytoma: a review

BACKGROUND

Pheochromocytomas are rare catecholamine-secreting tumors. Approximately 10 percent of pheochromocytomas are malignant. Traditionally, there has been no reliable method available to predict the malignant potential of pheochromocytoma. However, recent research has increased focus on differentiating at the time of surgery/diagnosis those pheochromocytoma tumors which have malignant potential. In this review, we discuss the current information known of malignant pheochromocytomas.

DATA SOURCES

The PubMed database was searched for articles on malignant pheochromocytoma published between 1993 and 2010.

CONCLUSIONS

The difficult task of predicting the malignant potential of a pheochromocytoma has yet to be answered definitively. However, all the studies presented give an idea of what we may look for in these tumors at the time of diagnosis. We have provided an algorithm based on the most current information known. A much larger study should be performed to test many of these theories with enough power to determine a standard of care.

Granins and their derived peptides in normal and tumoral chromaffin tissue: Implications for the diagnosis and prognosis of pheochromocytoma

Pheochromocytomas are rare catecholamine-secreting tumors that arise from chromaffin tissue within the adrenal medulla and extra-adrenal sites. Typical clinical manifestations are sustained or paroxysmal hypertension, severe headaches, palpitations and sweating resulting from hormone excess. However, their presentation is highly variable and can mimic many other diseases. The diagnosis of pheochromocytomas depends mainly upon the demonstration of catecholamine excess by 24-h urinary catecholamines and metanephrines or plasma metanephrines. Occurrence of malignant pheochromocytomas can only be asserted by imaging of metastatic lesions, which are associated with a poor survival rate. The characterization of tissue, circulating or genetic markers is therefore crucial for the management of these tumors. Proteins of the granin family and their derived peptides are present in dense-core secretory vesicles and secreted into the bloodstream, making them useful markers for the identification of neuroendocrine cells and neoplasms. In this context, we will focus here on reviewing the distribution and characterization of granins and their processing products in normal and tumoral chromaffin cells, and their clinical usefulness for the diagnosis and prognosis of pheochromocytomas. It appears that, except SgIII, all members of the granin family i.e. CgA, CgB, SgII, SgIV-SgVII and proSAAS, and most of their derived peptides are present in adrenomedullary chromaffin cells and in pheochromocytes. Moreover, besides the routinely used CgA test assays, other assays have been developed to measure concentrations of tissue and/or circulating granins or their derived peptides in order to detect the occurrence of pheochromocytomas. In most cases, elevated levels of these entities were found, in correlation with tumor occurrence, while rarely discriminating between benign and malignant neoplasms. Nevertheless, measurement of the levels of granins and derived peptides improves the diagnostic sensitivity and may therefore provide a complementary tool for the management of pheochromocytomas. However, the existing data need to be substantiated in larger groups of patients, particularly in the case of malignant disease.

Pheochromocytoma and paraganglioma

Pheochromocytoma is a very special kind of tumor full of duplicity. On the one hand it represents its own microworld with unique clinical, biochemical and pathological features, while on the other it constitutes a tremendously significant part of whole body system, playing a vital role for practically every organ system. It has a very special character - sometimes like a child it can be sweet and predictable, while at times it can behave like a deadly wild beast, crashing and tearing everything on its path in a fierce rage. It also consists of the amazingly intelligent neuroendocrine cells that possess a magical ability to make miraculous substances of many kinds. But most of all, it is a system that is able to drive our curiosity and the itch of "Cogito, ergo sum" to limitless depths and year by year it still amazes us with new and unexpected discoveries that move our understanding of multiple pathways and metabolic events closer to the ultimate truth. Recent discoveries of succinate dehydrogenase (SHD) and prolyl hydroxylase (PHD) mutations, for example, propelled our understanding of neuroendocrine tumorigenesis as a whole, as well as physiology of mitochondrial respiratory chain and phenomenon of pseudohypoxia in particular. Good old discoveries make their way from dusty repositories to shine with new meaning, appropriate for the current level of knowledge. This acquired wisdom makes us better physicians - knowing the specific expression makeup of catecholamine transporters, GLUTs and SRIFs allows for better tailored imaging and therapeutic manipulations. There are still long ways to go, keeping in mind that pheochromocytoma is but so very special, and we are optimistic and expect many great things to come.

Treatment of malignant pheochromocytoma

Pheochromocytoma (PCC) is a rare disease, mainly sporadic, but also associated with some familial disorders, with a malignancy frequency of approximately 10%. Only the presence of distant metastases, derived from large pleomorphic chromaffin cells, is widely accepted as a criterion of malignancy. Variable symptoms may be caused by production and release of catecholamines. Since there is no curative treatment for malignant PCC and due to its unfavorable prognosis, assuring quality of life is one of the main therapeutic objectives. Besides a long-term medical treatment of symptoms using selective alpha-1 blockers and nonselective, noncompetitive alpha- and/or beta-blockers, debulking surgery is the first treatment step. In case of a sufficient uptake of (123)I-MIBG treatment with targeted radiation therapy, use of (131)I-MIBG is an option as an adjuvant therapy, following debulking surgery. Chemotherapy should be applied to patients without positive MIBG-scan, with no response to (131)I-MIBG or progression after radionuclide treatment, and especially in cases with high proliferation index. The most effective chemotherapy regimen appears to be the CVD-scheme, including cyclophosphamide, vincristine, and dacarbazine. The so-called targeted molecular therapies with treatment combinations of temozolomide and thalidomide, or sunitinib monotherapy, and novel therapeutic somatostatin analogues have shown promising results and should thus encourage clinical trials to improve the prognosis of metastatic PCC. Within this review the current treatment modalities and novel molecular strategies in the management of this disease are discussed and a treatment algorithm is suggested.

Genetic markers for the diagnosis and prognosis of pheochromocytoma

The last 5 years have witnessed important advances in understanding the mechanisms of tumorigenesis of chromaffin cells. Large-scale microarray analyses of pheochromocytomas have identified two distinct gene-expression profiles encompassing all hereditary and sporadic tumors. Gene-expression profiling of benign and malignant pheochromocytomas is providing a better understanding of the mechanisms of metastasis. Such studies hold promise for the development of new prognostic markers for early detection of malignant pheochromocytoma and for the identification of novel targets for therapeutic intervention.

Clinical Use of Laboratory Tests for the Identification of Secondary Forms of Arterial Hypertension

The prevalence of secondary hypertension can be underestimated if appropriate tests are not performed. The importance of selecting patients with a high pre-test probability of secondary forms of hypertension is first discussed. The laboratory tests currently used for seeking a cause of hypertension are critically reviewed, with emphasis on their operative features and limitations. Strategies to identify primary aldosteronism, the most frequent form of secondary hypertension, and to determine its unilateral or bilateral causes are described. Treatment entails adrenalectomy in unilateral forms, and mineralocorticoid receptor blockade in bilateral forms. Renovascular hypertension is also a common, curable form of hypertension, that should be identified as early as possible to avoid the onset of cardiovascular target organ damage. The tests for its confirmation or exclusion are discussed. The various tests available for the diagnosis of pheochromocytoma, which is much rarer than the above but extremely important to identify, are also described, with emphasis on recent developments in genetic testing. Finally, the tests for diagnosing some rarer monogenic forms and other renal and endocrine causes of arterial hypertension are explored.

Development of differential diagnosis for benign and malignant pheochromocytomas

Unlike common malignant tumors, malignant pheochromocytomas cannot be definitely diagnosed using histological features. This unique nature of pheochromocytomas provides a valuable model that may promote the investigation of the mechanism of other common malignant tumors where similar frameworks are not available. Studies on malignant pheochromocytomas should benefit not only the individuals with pheochromocytomas but those with other tumors. A review on the development of differentiating diagnosis between malignant and benign pheochromocytomas in imaging studies, biological fluid examinations, pathological examinations, molecular markers and genome studies, was updated in the hopes of guiding the next studies of pheochromcytomas.

Diseases of the adrenal medulla

The adrenal glands are vital in the organism's response to environmental stress. The outer cortex releases steroid hormones: glucocorticoids, mineralocorticoids and sex hormones, which are crucial to metabolism, inflammatory reactions and fluid homeostasis. The medulla is different developmentally, functionally and structurally. It co-releases catecholamines (primarily adrenaline and to some extent noradrenaline) as well as peptides by the all-or-none process of exocytosis from chromaffin granules, to aid in blood pressure and blood flow regulation, with regulated increments during the activation of the sympathetic nervous system. The co-released peptides function to regulate catecholamine release, blood vessel contraction and innate immune responses. Pathology within the adrenal medulla and the autonomic nervous system is primarily because of neoplasms. The most common tumour, called phaeochromocytoma when located in the adrenal medulla, originates from chromaffin cells and excretes catecholamines, but may be referred to as secreting paragangliomas when found in extra-adrenal chromaffin cells. Neoplasms, such as neuroblastomas and ganglioneuromas, may also be of neuronal lineage. We will also briefly discuss the catecholamine deficiency state.

Malignant pheochromocytoma: state of the field with future projections

The prevalence of malignant pheochromocytoma is about 10%, and is somewhat higher for paraganglioma. A problem for clinical follow-up is that patients with "benign" histopathologic findings may develop metastatic disease. At the first international symposium on pheochromocytoma in Bethesda (2005) experts from different disciplines and patients shared their experiences, and the present knowledge of this rare disease was updated. The discussion related to future strategies for better clinical/histopathologic diagnosis and understanding of different geno- and phenotypes. Curative surgery can only seldom be performed because of multiple metastases. The main therapeutic goal is therefore often tumor reduction and control of hypertension. To date the best adjunct to surgery is radionuclide therapy using 131I-MIBG, but the background information for optimal treatment is still incomplete. Certain patients may benefit from 131I-MIBG combined with radiotherapy via somatostatin receptors expressed by the tumor, or the combination with chemotherapy. The need for future multicenter studies was emphasized. In experimental models the work on enhanced expression of amine transporters critical for radiotherapy is continued. Ongoing microarray studies will reveal novel intracellular pathways of importance for proliferation/cell cycle control, which can be inhibited by pharmacologic tools.

Gene expression profiling of benign and malignant pheochromocytoma

There are currently no reliable diagnostic and prognostic markers or effective treatments for malignant pheochromocytoma. This study used oligonucleotide microarrays to examine gene expression profiles in pheochromocytomas from 90 patients, including 20 with malignant tumors, the latter including metastases and primary tumors from which metastases developed. Other subgroups of tumors included those defined by tissue norepinephrine compared to epinephrine contents (i.e., noradrenergic versus adrenergic phenotypes), adrenal versus extra-adrenal locations, and presence of germline mutations of genes predisposing to the tumor. Correcting for the confounding influence of noradrenergic versus adrenergic catecholamine phenotype by the analysis of variance revealed a larger and more accurate number of genes that discriminated benign from malignant pheochromocytomas than when the confounding influence of catecholamine phenotype was not considered. Seventy percent of these genes were underexpressed in malignant compared to benign tumors. Similarly, 89% of genes were underexpressed in malignant primary tumors compared to benign tumors, suggesting that malignant potential is largely characterized by a less-differentiated pattern of gene expression. The present database of differentially expressed genes provides a unique resource for mapping the pathways leading to malignancy and for establishing new targets for treatment and diagnostic and prognostic markers of malignant disease. The database may also be useful for examining mechanisms of tumorigenesis and genotype-phenotype relationships. Further progress on the basis of this database can be made from follow-up confirmatory studies, application of bioinformatics approaches for data mining and pathway analyses, testing in pheochromocytoma cell culture and animal model systems, and retrospective and prospective studies of diagnostic markers.

Malignant Pheochromocytomas and Paragangliomas: A Phase II Study of Therapy with High-Dose 131I-Metaiodobenzylguanidine (131I-MIBG)

Thirty patients with malignant pheochromocytoma (PHEO) or paraganglioma (PGL) were treated with high-dose 131I-MIBG. Patients were 11-62 (mean 39) years old: 19 patients males and 11 females. Nineteen patients had PGL, three of which were multifocal. Six PGLs were nonsecretory. Eleven patients had PHEO. All 30 patients had prior surgery. Fourteen patients were refractory to prior radiation or chemotherapy before 131I-MIBG. Peripheral blood stem cells (PBSCs) were collected and cryopreserved. 131I-MIBG was synthesized on-site, by exchange-labeling 131I with 127I-MIBG in a solid-phase Cu2+-catalyzed exchange reaction. 131I-MIBG was infused over 2 h via a peripheral IV. Doses ranged from 557 mCi to 1185 mCi (7.4 mCi/kg to 18.75 mCi/kg). Median dose was 833 mCi (12.55 mCi/kg). Marrow hypoplasia commenced 3 weeks after 131I-MIBG therapy. After the first 131I-MIBG therapy, 19 patients required platelet transfusions; 19 received GCSF; 12 received epoeitin or RBCs. Four patients received a PBSC infusion. High-dose 131I-MIBG resulted in the following overall tumor responses in 30 patients: 4 sustained complete remissions (CRs); 15 sustained partial remissions (PRs); 1 sustained stable disease (SD); 5 progressive disease (PD); 5 initial PRs or SD but relapsed to PD. Twenty-three of the 30 patients remain alive; deaths were from PD (5), myelodysplasia (1), and unrelated cause (1). Overall predicted survival at 5 years is 75% (Kaplan Meier estimate). For patients with metastatic PHEO or PGL, who have good *I-MIBG uptake on diagnostic scanning, high-dose 131I-MIBG therapy was effective in producing a sustained CR, PR, or SD in 67% of patients, with tolerable toxicity.

Malignant Pheochromocytoma

Malignant pheochromocytoma is a rare disease with a high mortality. Surgical resection is the only effective treatment if extensive metastatic disease is not present. However, differentiating between benign and malignant pheochromocytoma is impossible in the absence of locoregional invasion or distant metastasis. This diagnostic dilemma has several drawbacks, including later detection and treatment of recurrence than if malignancy is determined at the original operation. With emerging molecular markers of malignant disease, optimal extent and approach for surgical treatment and appropriate extent of follow up could be established based on specific tumor behavior and the need for additional systemic therapy.

Circulating EM66 is a highly sensitive marker for the diagnosis and follow-up of pheochromocytoma

We have previously demonstrated that measurement of tissue concentration of the novel secretogranin II-derived peptide EM66 may help to discriminate between benign and malignant pheochromocytomas. The aim of the present study was to characterize EM66 in plasma and urine of healthy volunteers and pheochromocytoma patients, in order to further evaluate the usefulness of this peptide as a circulating marker for the management of the tumors. HPLC analysis of plasma and urine samples demonstrated that the EM66-immunoreactive material coeluted with the recombinant peptide. In healthy volunteers, plasma and urinary EM66 levels were, respectively, 2.6 (1.9-3.7) ng/ml and 2.9 (1.9-4.6) ng/ml. In patients with pheochromocytoma, plasma EM66 levels were 10-fold higher than those of healthy volunteers (26.9 (7.3-44) ng/ml), and returned to normal values after removal of the tumor. In contrast, urinary EM66 levels were not significantly different from those of healthy volunteers (3.2 (2.2-3.9) ng/ml). Measurement of total or free plasma metanephrines and 24 hr urinary metanephrines in our series of patients revealed that these tests, taken separately, are less sensitive than the EM66 determination. Pheochromocytes in primary culture secreted high levels of EM66, suggesting that the chromaffin tumor was actually responsible for the increased plasma peptide concentrations in the patients. These data indicate that EM66 is secreted in the general circulation and that elevated plasma EM66 levels are correlated with the occurrence of pheochromocytoma. Thus, EM66 is a sensitive plasma marker that should be considered as a complementary tool in the management of pheochromocytoma.

Phaeochromocytoma

Phaeochromocytomas are rare neuroendocrine tumours with a highly variable clinical presentation but most commonly presenting with episodes of headaches, sweating, palpitations, and hypertension. The serious and potentially lethal cardiovascular complications of these tumours are due to the potent effects of secreted catecholamines. Biochemical testing for phaeochromocytoma is indicated not only in symptomatic patients, but also in patients with adrenal incidentalomas or identified genetic predispositions (eg, multiple endocrine neoplasia type 2, von Hippel-Lindau syndrome, neurofibromatosis type 1, and mutations of the succinate dehydrogenase genes). Imaging techniques such as CT or MRI and functional ligands such as (123)I-MIBG are used to localise biochemically proven tumours. After the use of appropriate preoperative treatment to block the effects of secreted catecholamines, laparoscopic tumour removal is the preferred procedure. If removal of phaeochromocytoma is timely, prognosis is excellent. However, prognosis is poor in patients with metastases, which especially occur in patients with large, extra-adrenal tumours.

The diagnosis and medical management of advanced neuroendocrine tumors

Neuroendocrine tumors (NETs) constitute a heterogeneous group of neoplasms that originate from endocrine glands such as the pituitary, the parathyroids, and the (neuroendocrine) adrenal, as well as endocrine islets within glandular tissue (thyroid or pancreatic) and cells dispersed between exocrine cells, such as endocrine cells of the digestive (gastroenteropancreatic) and respiratory tracts. Conventionally, NETs may present with a wide variety of functional or nonfunctional endocrine syndromes and may be familial and have other associated tumors. Assessment of specific or general tumor markers offers high sensitivity in establishing the diagnosis and can also have prognostic significance. Imaging modalities include endoscopic ultrasonography, computed tomography and magnetic resonance imaging, and particularly, scintigraphy with somatostatin analogs and metaiodobenzylguanidine. Successful treatment of disseminated NETs requires a multimodal approach; radical tumor surgery may be curative but is rarely possible. Well-differentiated and slow-growing gastroenteropancreatic tumors should be treated with somatostatin analogs or alpha-interferon, with chemotherapy being reserved for poorly differentiated and progressive tumors. Therapy with radionuclides may be used for tumors exhibiting uptake to a diagnostic scan, either after surgery to eradicate microscopic residual disease or later if conventional treatment or biotherapy fails. Maintenance of the quality of life should be a priority, particularly because patients with disseminated disease may experience prolonged survival.

High-dose 131I-metaiodobenzylguanidine therapy for 12 patients with malignant pheochromocytoma

BACKGROUND

131I-Metaiodobenzylguanidine (131I-MIBG) can be used systemically to treat malignant pheochromocytoma. To improve outcome, the authors used higher levels of activity of 131I-MIBG than previously reported. The authors reported the response rates and toxicity levels in patients with malignant pheochromocytoma or paraganglioma who were treated with high-dose 131I-MIBG.

METHODS

Following debulking surgery and stem cell harvest, 12 patients with malignant pheochromocytoma or paraganglioma were treated with 131I-MIBG. Five had received previous external beam radiation and/or chemotherapy. The median single treatment dose was 800 mCi (37 gigabecquerels; range, 386-866 mCi) or 11.5 mCi/kg (range, 5.6-18.3 mCi/kg). The median cumulative dose was 1015 mCi (range, 386-1690 mCi).

RESULTS

Three patients had a complete response, two of whom had soft tissue and skeletal metastases. Their median follow-up was 45 months (range, 23-101 months). Seven patients had a partial response (PR), with a median follow-up 43 months (range, 6-47 months). Two patients without a response died with progressive disease (PD) and 2 patients with an initial PR died of PD at 13 and 11 months, respectively. Grade 3 thrombocytopenia occurred after 79% (15 of 19) of treatments had been administered. Grade 3 and 4 neutropenia followed 53% (10 of 19) and 19% (4 of 19) of treatments, respectively. One patient required stem cell infusion, and one developed primary ovarian failure.

CONCLUSIONS

The single and cumulative doses of 131I-MIBG were approximately 2-3.5 times higher than those used at other centers. Unlike previous reports, two patients with both skeletal and soft tissue metastases had a complete response. Hematologic toxicity was significant but tolerable. High-dose 131I-MIBG may lead to long-term survival in patients with malignant pheochromocytoma.