The many faces of pheochromocytoma

Pheochromocytomas and Paragangliomas

Pheochromocytomas are rare neuroendocrine tumors. Extra-adrenal lesions arising from the autonomic neural ganglia are termed paraganglioma. Clinical symptoms are common between the adrenal and extra-adrenal forms and are determined by excess secretion of catecholamines. Hypertension is a critical and often dramatic feature of pheochromocytoma/paraganglioma, and its most prevalent reported symptom. However, given the rare occurrence of this cancer, in patients undergoing screening for hypertension, the prevalence ranges from 0.1% to 0.6%. Still, patients frequently come to the attention of endocrinologist when pheochromocytoma/paraganglioma is suspected as a secondary cause of hypertension. This article summarizes current clinical approaches in patients with pheochromocytoma/paraganglioma.

Pheochromocytoma/Paraganglioma: A Poster Child for Cancer Metabolism

CONTEXT

Pheochromocytomas (PCCs) are tumors that are derived from the chromaffin cells of the adrenal medulla. Extra-adrenal PCCs called paragangliomas (PGLs) are derived from the sympathetic and parasympathetic chain ganglia. PCCs secrete catecholamines, which cause hypertension and have adverse cardiovascular consequences as a result of catecholamine excess. PGLs may or may not produce catecholamines depending on their genetic type and anatomical location. The most worrisome aspect of these tumors is their ability to become aggressive and metastasize; there are no known cures for metastasized PGLs.

METHODS

Original articles and reviews indexed in PubMed were identified by querying with specific PCC/PGL- and Krebs cycle pathway-related terms. Additional references were selected through the in-depth analysis of the relevant publications.

RESULTS

We primarily discuss Krebs cycle mutations that can be instrumental in helping investigators identify key biological pathways and molecules that may serve as biomarkers of or treatment targets for PCC/PGL.

CONCLUSION

The mainstay of treatment of patients with PCC/PGLs is surgical. However, the tide may be turning with the discovery of new genes associated with PCC/PGLs that may shed light on oncometabolites used by these tumors.

Laparoscopic adrenalectomy for nonfamilial adrenal medullary hyperplasia

Sporadic adrenomedullary hyperplasia may mimic pheochromocytoma. Laparoscopic adrenalectomy is recommended for the management of this entity.

Background and Objectives:

Sporadic adrenomedullary hyperplasia (AMH) is characterized by a medical history of hypertension, excessive catecholamine excretion, and histomorphometric evidence of increased adrenomedullary tissue relative to the cortex in the absence of multiple endocrine neoplasia. The aim of this study was to perform a retrospective analysis of patients after laparoscopic adrenalectomy for AMH, an early form of sporadic adrenal medulla–related endocrine hypertension, as well as to update our understanding of the clinical features and management of this clinicomorphologic entity.

Methods:

We performed a retrospective review of the medical records of patients operated on between 2007 and 2011 at Reina Sofia University General Hospital, Murcia, Spain, with a diagnosis of AMH. Patient characteristics, diagnostic studies, surgical procedures, and histologic findings were analyzed.

Results:

Seven hypertensive patients with intermittent adrenergic crises were found to have AMH (3 men and 4 women; mean age, 44 years). Catecholamine levels were increased. Radiologic studies included 1 or more of the following: magnetic resonance imaging, computed tomography, positron emission tomography imaging with fluorodeoxyglucose, dihydroxyphenylalanine–positron emission tomography–computed tomography, Octreoscan (Mallinckrodt Pharmaceuticals, St. Louis, MO, USA) and ¹²³I-metaiodobenzylguanidine scintigraphy. Laparoscopic adrenalectomy was performed in all cases. One patient underwent bilateral adrenalectomy because of persistent symptomatology after unilateral adrenalectomy. Surgery was associated with normalization of catecholamine hypersecretion and complete disappearance of symptoms, as well as the reduction or abstention of antihypertensive therapy.

Conclusions:

Sporadic AMH is a clinicomorphologic entity that may mimic pheochromocytoma clinically. Recent advances in diagnostic and surgical methods have changed the management and outcome of this unusual disease. Laparoscopic adrenalectomy may be recommended as the gold standard in the treatment of this entity. Definitive diagnosis is provided by histologic study.

Phospho-mTOR is not upregulated in metastatic SDHB paragangliomas

BACKGROUND

Pheochromocytomas (PCCs)/paragangliomas (PGLs) are neuroendocrine tumours that may cause arrhythmia and death if untreated. Treatment for patients with metastatic tumours is lacking. As new PCC/PGL susceptibility genes are discovered that are associated with the mTOR pathway, treatment targets focusing on this pathway are being intensively explored.

DESIGN

Twenty-one human PCC/PGLs were analysed from two tertiary care centres. Immunohistochemistry (IHC) analysis was performed for phospho-mTOR (pmTOR), phospho-S6K (pS6K), phosphoinositide 3-kinase (PI3K), phospho-4EBP1 (p4EBP1), HIF1α and MIB-1 in 6 metastatic SDHB PCC/PGLs, 15 nonmetastatic PCC/PGLs, (including 1 TMEM127 PCC and 1 nonmetastatic SDHB PGL) and 6 normal adrenal medullas. The product of the intensity of stain and percentage of cells stained was calculated as an H score.

RESULTS

Using a two-sample t-test and paired t-test, pmTOR and pS6K had significantly higher H scores in nonmetastatic PCC/PGLs than in metastatic SDHB PCC/PGLs. HIF1α had significantly higher H scores in metastatic SDHB PCC/PGLs compared with nonmetastatic PCC/PGLs and normal adrenal medulla. No difference in H scores was seen with p4EBP1, PI3K and MIB-1 when comparing metastatic SDHB PCC/PGLs and nonmetastatic PCC/PGLs. Significantly higher difference in pS6K was seen in normal adrenal medullas compared to nonmetastatic PCC/PGLs and metastatic SDHB PCC/PGLs.

CONCLUSION

The present results suggest that the use of mTOR inhibitors alone for metastatic SDHB PCC/PGLs may not achieve good therapeutic efficacy in patients.

Progenitor cell line (hPheo1) derived from a human pheochromocytoma tumor

Background

Pheochromocytomas are rare tumors generally arising in the medullary region of the adrenal gland. These tumors release excessive epinephrine and norepinephrine resulting in hypertension and cardiovascular crises for which surgery is the only definitive treatment. Molecular mechanisms that control tumor development and hormone production are poorly understood, and progress has been hampered by the lack of human cellular model systems. To study pheochromocytomas, we developed a stable progenitor pheochromocytoma cell line derived from a primary human tumor.

Methods

After IRB approval and written informed consent, human pheochromocytoma tissue was excised, minced, dispersed enzymatically, and cultured in vitro. Primary pheochromocytoma cells were infected with a lentivirus vector carrying the catalytic subunit of human telomerase reverse transcriptase (hTERT). The hTERT immortalized cells (hPheo1) have been passaged >300 population doublings. The resulting cell line was characterized morphologically, biochemically and for expression of neuroendocrine properties. The expression of marker enzymes and proteins was assessed by immunofluorescence staining and immunoblotting. Telomerase activity was determined by using the telomeric repeat amplification protocol (TRAP) assay.

Results

We have established a human pheochromocytoma precursor cell line that expresses the neuroendocrine marker, chromogranin A, when differentiated in the presence of bone morphogenic protein 4 (BMP4), nerve growth factor (NGF), and dexamethasone. Phenylethanolamine N-methyltransferase (PNMT) expression is also detected with this differentiation regimen. CD-56 (also known as NCAM, neural cell adhesion molecule) is expressed in these cells, but CD31 (also known as PECAM-1, a marker of endothelial cells) is negative.

Conclusions

We have maintained hTERT-immortalized progenitor cells derived from a pheochromocytoma (hPheo1) in culture for over 300 population doublings. This progenitor human cell line is normal diploid except for a deletion in the p16 region and has inducible neuroendocrine biomarkers. These cells should be a valuable reagent for studying mechanisms of tumor development and for testing novel therapeutic approaches.

Systematic review of phaeochromocytoma in pregnancy

Background

Phaeochromocytoma in pregnancy is a rare and potentially dangerous situation for mother and fetus. This review aimed to assess current mortality rates and how medical and surgical management affect these.

Methods

Articles in English published between 2000 and 2011 were obtained from a MEDLINE search. Eligible publications presented women diagnosed with phaeochromocytoma in the antenatal or immediate postnatal period, and reported management and outcomes.

Results

A total of 135 reports were identified. After applying inclusion criteria, 77 pregnancies involving 78 fetuses were analysed. Fetal and maternal mortality rates were 17 per cent (13 of 78) and 8 per cent (6 of 77) respectively. Better outcomes were achieved when the diagnosis of phaeochromocytoma was made in the antenatal period than when it was made during labour or immediately postpartum (survival of both mother and fetus(es) in 48 of 56 versus 12 of 21 respectively; P = 0·012). When the diagnosis was made before 23 weeks' gestation, there was no difference in outcomes when phaeochromocytoma surgery was carried out in the second trimester, compared with when it was postponed to the third trimester or after delivery (fetal death 2 of 18 versus 2 of 8 respectively; P = 0·563).

Conclusion

This review, although limited by the rarity of the condition and level of available evidence, demonstrated that survival rates are improved if the diagnosis of phaeochromocytoma can be established antenatally. With diagnosis before 23 weeks' gestation, no definite advantage of proceeding with tumour removal during the second trimester could be demonstrated.

Pheochromocytoma and medullary thyroid carcinoma in a pregnant multiple endocrine neoplasia-2A patient

OBJECTIVE

We describe a rare combination of pheochromocytoma and medullary thyroid carcinoma (MTC) during pregnancy.

METHODS

Twenty-three-years old lady, primigravida, was detected to be hypertensive at 12 weeks of gestation and was found to have left adrenal mass on routine obstetric scan. She had a goitre on examination which was proven to be MTC on fine needle aspiration cytology. Twenty-four hours urinary vanillyl mandelic acid and serum calcitonin levels were elevated. After adequate α and β blockade she underwent left adrenalectomy during second trimester of gestation with no significant perioperative complications. Twelve days later she underwent total thyroidectomy.

RESULTS

Adrenal mass was confirmed to be pheochromocytoma while MTC was confirmed in the thyroidectomy specimen. Post-operatively, she was normotensive and delivered a healthy female baby at term. Both mother and the baby tested positive for germline RET mutation (C634W) in exon 11.

CONCLUSION

We describe a rare case of pregnant multiple endocrine neoplasia-2A patient with pheochromocytoma and MTC.

Pheochromocytoma and pregnancy: a rare but dangerous combination

OBJECTIVE

To review the literature on pheochromocytoma in pregnancy (PIP) published during the 11-year period 1998 through 2008.

METHODS

We searched MEDLINE data sources from 1998 through 2008 using the search terms "pheochromocytoma" and "pregnancy" and reviewed case reports of PIP published in English.

RESULTS

We identified 54 case reports in MEDLINE data sources, of which 51 reports including 60 cases were reviewed. In comparison with the previous decade, a decreased rate of antenatal diagnosis (from 83% to 70%) and increased maternal and fetal mortality (from 4% to 12% and from 10% to 17%, respectively) were observed. Prematurity was present in 53% of the infants of mothers with antenatally diagnosed pheochromocytoma who gave birth to a live infant. Hypertension was the most common manifestation (88%), with 33% of patients having antepartum hypertensive crises. Urinary catecholamines (64%) and metanephrines (40%) were the most commonly used tests, whereas urinary and plasma metanephrines were the most sensitive tests (100%). Ultrasonography had poor sensitivity (54%), especially during the third trimester. Magnetic resonance imaging was 100% sensitive for adrenal tumors but had only 50% sensitivity for extra-adrenal tumors. A syndromic or familial presentation was seen in 18% of patients, and 32% of patients had bilateral or extra-adrenal tumors.

CONCLUSION

In comparison with the previous decade, a decreased rate of antenatal diagnosis and increased maternal and fetal mortality were observed. Prematurity was a major morbidity associated with PIP. Hypertensive crises were more common during pregnancy. Urinary and plasma metanephrines had the highest sensitivity to detect PIP. Genetic screening should be offered to all pregnant women with pheochromocytoma.