Extra-adrenal pheochromocytoma. Some electron microscopic and biochemical studies

15 YEARS OF PARAGANGLIOMA: Pheochromocytoma, paraganglioma and genetic syndromes: a historical perspective

The last decades have elucidated the genetic basis of pheochromocytoma (PC) and paraganglioma (PGL) (PCPGL)-associated hereditary syndromes. However, the history of these syndromes dates back at least another 150 years. Detailed descriptions by clinicians and pathologists in the 19th and 20th centuries led to the recognition of the PCPGL-associated syndromes von Hippel-Lindau disease, neurofibromatosis type 1, and multiple endocrine neoplasia type 2. In the beginning of the current millennium the molecular basis of the hereditary PGL syndrome was elucidated by the discovery of mutations in genes encoding enzymes of the Krebs cycle, such as succinate dehydrogenase genes (SDHx) and other mutations, causing 'pseudo-hypoxia' signaling. These recent developments also marked a paradigm shift. It reversed the traditional order of genetic research that historically aimed to define the genetic basis of a known hereditary syndrome but now is challenged with defining the full clinical phenotype associated with a newly defined genetic basis. This challenge underscores the importance to learn from medical history, continue providing support for clinical research, and train physicians with regards to their skills to identify patients with PCPGL-associated syndromes to extend our knowledge of the associated phenotype. This historical overview provides details on the history of the paraganglial system and PCPGL-associated syndromes. As such, it hopefully will not only be an interesting reading for the physician with a historical interest but also emphasize the necessity of ongoing astute individual clinical observations and clinical registries to increase our knowledge regarding the full phenotypic spectrum of these conditions.

Pheochromocytoma and paraganglioma in cyanotic congenital heart disease

CONTEXT

Aberrant cellular oxygen sensing is a leading theory for development of pheochromocytoma (PHEO) and paraganglioma (PGL).

OBJECTIVE

The objective of the study was to test the hypothesis that chronic hypoxia in patients with cyanotic congenital heart disease (CCHD) increases the risk for PHEO-PGL.

DESIGN/SETTING/PARTICIPANTS

We investigated the association between CCHD and PHEO-PGL with two complementary studies: study 1) an international consortium was established to identify congenital heart disease (CHD) patients with a PHEO-PGL diagnosis confirmed by pathology or biochemistry and imaging; study 2) the 2000-2009 Nationwide Inpatient Survey, a nationally representative discharge database, was used to determine population-based cross-sectional PHEO-PGL frequency in hospitalized CCHD patients compared with noncyanotic CHD and those without CHD using multivariable logistic regression adjusted for age, sex, and genetic PHEO-PGL syndromes.

RESULTS

In study 1, we identified 20 PHEO-PGL cases, of which 18 had CCHD. Most presented with cardiovascular or psychiatric symptoms. Median cyanosis duration for the CCHD PHEO-PGL cases was 20 years (range 1-57 y). Cases were young at diagnosis (median 31.5 y, range 15-57 y) and 7 of 18 had multiple tumors (two bilateral PHEO; six multifocal or recurrent PGL), whereas 11 had single tumors (seven PHEO; four PGL). PGLs were abdominal (13 of 17) or head/neck (4 of 17). Cases displayed a noradrenergic biochemical phenotype similar to reported hypoxia-related PHEO-PGL genetic syndromes but without clinical signs of such syndromes. In study 2, hospitalized CCHD patients had an increased likelihood of PHEO-PGL (adjusted odds ratio 6.0, 95% confidence interval 2.6-13.7, P < .0001) compared with those without CHD; patients with noncyanotic CHD had no increased risk (odds ratio 0.9, P = .48).

CONCLUSIONS

There is a strong link between CCHD and PHEO-PGL. Whether these rare diseases coassociate due to hypoxic stress, common genetic or developmental factors, or some combination requires further investigation.

Familial pheochromocytomas and paragangliomas

Pheochromocytomas and paragangliomas are neural crest cell tumors of the adrenal medulla and parasympathetic/sympathetic ganglia, respectively, that are often associated with catecholamine production. Genetic research over the years has led to our current understanding of the association 13 susceptibility genes with the development of these tumors. Most of the susceptibility genes are now associated with specific clinical presentations, biochemical makeup, tumor location, and associated neoplasms. Recent scientific advances have highlighted the role of somatic mutations in the development of pheochromocytoma/paraganglioma as well as the usefulness of immunohistochemistry in triaging genetic testing. We can now approach genetic testing in pheochromocytoma/paraganglioma patients in a very organized scientific way allowing for the reduction of both the financial and emotional burden on the patient. The discovery of genetic predispositions to the development of pheochromocytoma/paraganglioma not only facilitates better understanding of these tumors but will also lead to improved diagnosis and treatment of this disease.

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.

Organs of Zuckerkandl: their surgical significance and a review of a century of literature

BACKGROUND

Organs of Zuckerkandl (O of Z) harbor the potential for deadly paragangliomas. Paragangliomas are one of the surgical causes of hypertension. Major treatises of medicine offer very little information on this topic.

METHODS

PubMed Medline and Google searches were performed to obtain reported cases of paragangliomas of the O of Z. A total of 135 cases of paragangliomas of the O of Z were found. Each case was reviewed and charted. Charts then were analyzed.

RESULTS

Seventy-four percent of patients with this neoplasm have hypertension. Eighty percent of patients undergo an operation with more than 30% having an incorrect preoperative diagnosis. These tumors have a 43% mortality when presenting acutely.

CONCLUSIONS

Individuals aged < or =50 years with hypertension should be considered for screening for pheochromocytoma/paraganglioma with uring and/or serum catecholamines. Twenty-four-hour collections for urinary metanephrines and vanillylmandelic acid are diagnostic of functional tumors. A high degree of suspicion should follow with radiologic and chemical diagnostic studies. Triple-phase helical computed tomographic scans, metaiodobenzyl-guanidine scans, and magnetic resonance imaging with gadolinium-diethylenetriaminepentaacetic acid infusion are the standard for radiologic diagnosis. Treatment is always surgical excision. Phase II trials are in order for neoadjuvant and adjuvant treatment options.

Giant mitochondria with paracrystalline inclusions in paraganglioma of the urinary bladder: correlation with mitochondrial abnormalities in paragangliomas of other sites

Mitochondrial abnormalities have received relatively little attention in the ultrastructural evaluation of paragangliomas. Review of the few literature references dealing with this issue, however, reveals that quantitative and qualitative changes of these organelles occur in that context. A bladder paraganglioma is described that was characterized by numerous mitochondria, which in addition displayed giant forms along with matrical paracrystalline inclusions. Upon retrospective review of 12 archival cases of paragangliomas, enlarged and structurally abnormal mitochondria were found in all of them. Although various speculations can be made, the mechanism of formation and the pathophysiologic significance of these abnormal mitochondria remain unknown. From a morphologic diagnostic point of view, however, these abnormalities, which in this case of bladder paraganglioma were also light microscopically evident, can be of significant help in establishing the correct diagnosis.

Clinico-pathological and ultrastructural characteristics of pheochromocytoma. An analysis of 55 cases

58 tumors of pheochromocytoma from 55 cases were studied clinico-pathologically and electron-microscopically. In this series, males were predominant and the number of left adrenal pheochromocytomas was 1.6 times that of right ones. Extraadrenal pheochromocytomas amounted to 41.4%. All 5 malignant pheochromocytomas in this series arose from extraadrenal paraganglia. Two types of secretory granules corresponding to the epinephrine and norepinephrine granules in the normal adrenal medulla were discerned in all 13 tumors examined under electron microscope. The contents of different types of granules were compared with urinary catecholamine excretion, and no apparent correlation was disclosed. Large amount of "E" granules in tumor cells of some cases might be associated with very low level of urinary epinephrine, while in the other cases, the reverse was true. The amount of catecholamine excreted in urine also bore no relation to the size of the tumor.

Ultrastructure of malignant paraganglioma of organ of Zuckerkandl

Electron microscopic study of a malignant paraganglioma of the organ of Zuckerkandl revealed similarities between the tumor and the normal paraganglia. The well-differentiated portion of the tumor recapitulated the structure of the basic functional units of the paraganglion. In addition there signs of anaplasia both at the histologic and ultrastructural level. Large neurosecretory granules were noted in some of the tumor cells, but most of the cells were agranular. Crystaloids resembling those seen in alveolar soft part sarcoma were also noted. The study supports the theory on the common origin and histogenesis of paragangliomas and alveolar soft part sarcomas.

Mitochondrial abnormalities in human phaeochromocytoma

Mitochondrial abnormalities are reported in four cases of phaeochromocytoma. These abnormalities include swelling and scant cristae, intramitochondrial dense bodies, septate-like junctions, intercristal fusion plus spheroidal bodies, and intramitochondrial rodlets. These structural mitochondrial changes are associated with reduction in activity of the mitochondrial enzymes, monoamine oxidase and succinic dehydrogenase.