Pheochromocytoma: Physiopathologic Implications and Diagnostic Evaluation

Bioapplications of Electrochemical Sensors and Biosensors

Recent progress in the electrochemical field enabled development of miniaturized sensing devices that can be used in biological settings to obtain fundamental and practical biochemically relevant information on physiology, metabolism, and disease states in living systems. Electrochemical sensors and biosensors have demonstrated potential for rapid, real-time measurements of biologically relevant molecules. This chapter provides an overview of the most recent advances in the development of miniaturized sensors for biological investigations in living systems, with focus on the detection of neurotransmitters and oxidative stress markers. The design of electrochemical (bio)sensors, including their detection mechanism and functionality in biological systems, is described as well as their advantages and limitations. Application of these sensors to studies in live cells, embryonic development, and rodent models is discussed.

Endocrine causes of dangerous fever

This article provides an overview of the pathogenesis and signs and symptoms of dangerous endocrine causes of hyperthermia. Treatment strategies based on specific causes are discussed.

Enhanced dense core granule function and adrenal hypersecretion in a mouse model of Rett syndrome

Rett syndrome (RTT) is a progressive developmental disorder resulting from loss-of-function mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2), a transcription regulatory protein. The RTT phenotype is complex and includes severe cardiorespiratory abnormalities, dysautonomia and behavioral symptoms of elevated stress. These findings have been attributed to an apparent hyperactivity of the sympathetic nervous system due to defects in brainstem development; however, the possibility that the peripheral sympathoadrenal axis itself is abnormal has not been explored. The present study demonstrates that the adrenal medulla and sympathetic ganglia of Mecp2 null mice exhibit markedly reduced catecholamine content compared with wild-type controls. Despite this, null animals exhibit significantly higher plasma epinephrine levels, suggesting enhanced secretory granule function in adrenal chromaffin cells. Indeed, we find that Mecp2 null chromaffin cells exhibit a cell autonomous hypersecretory phenotype characterized by significant increases in the speed and size of individual secretory granule fusion events in response to electrical stimulation. These findings appear to indicate accelerated formation and enhanced dilation of the secretory granule fusion pore, resulting in elevated catecholamine release. Our data therefore highlight abnormal catecholamine function in the sympathoadrenal axis as a potential source of autonomic dysfunction in RTT. These findings may help to explain the apparent 'overactivity' of the sympathetic nervous system reported in patients with RTT.

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

BACKGROUND

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

AIM AND METHODS

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

RESULTS

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

CONCLUSIONS

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

PET Imaging of Pheochromocytoma

Pheochromocytomas are tumors derived from chromaffin cells of the adrenal medulla that synthesize, store, metabolize, and usually, but not always, secrete catecholamines. Although pheochromocytomas are the cause of hypertension in only a small number of patients, they can precipitate life-threatening hypertension or cardiac arrhythmias caused by excessive and episodic catecholamine secretion. This article reviews the genetics, clinical presentation, and imaging of pheochromocytoma, with special emphasis on new positron emission tomographic radiopharmaceutical agents.

Malignant pheochromocytoma of the organ of Zuckerkandl requiring aortic and vena caval reconstruction

OBJECTIVE

To describe a case of a malignant pheochromocytoma located in the organ of Zuckerkandl that required aortic and vena caval resection and reconstruction.

METHODS

We present a case report that includes clinical, laboratory, and radiographic data as well as photographs, results from pathology, and a brief review of the literature.

RESULTS

A 46-year-old man was referred for evaluation of a 1.4-cm left adrenal mass incidentally discovered on an abdominopelvic computed tomography (CT) scan. Subsequent laboratory evaluation revealed the following values: urine norepinephrine, 252 microg/24 h; urine normetanephrine, 1122 microg/24 h; urine metanephrine, 162 microg/24 h; urine epinephrine, 7 microg/24 h; urine vanillylmandelic acid, 8 mg/24 h; and plasma metanephrine, 98 pg/ mL. Imaging characteristics of the left adrenal mass were consistent with a benign adenoma, but CT also demonstrated a hypervascular para-aortic mass. 123I-metaiodo-benzylguanidine scanning with fusion CT imaging demonstrated increased radiopharmaceutical uptake within the para-aortic mass consistent with a paraganglioma in the organ of Zuckerkandl. Findings from CT angiography of the abdomen and pelvis suggested aortic involvement and vena caval thrombus. The mass was excised en bloc, including portions of the aorta, inferior vena cava, and right ureter. The aorta and vena cava were reconstructed using Dacron grafts. The remaining right ureter and kidney were removed to avoid the possibility of a urine leak from an ureteroureterostomy. Final pathologic and operative findings confirmed a malignant pheochromocytoma of the organ of Zuckerkandl with invasion into the wall of the inferior vena cava and tumor thrombus extending into the lumen.

CONCLUSION

Malignant pheochromocytoma of the organ of Zuckerkandl involving the aorta and inferior vena cava is exceedingly rare, and although surgical resection and reconstruction can be radical and aggressive, this treatment offers the only chance for cure.