Diagnosis, Pathophysiology, and Molecular Biology of Pheochromocytoma and Paraganglioma
Pheochromocytomas/paragangliomas are rare but clinically important chromaffin cell tumors
that typically arise from the adrenal gland and constitute a surgically correctable cause of
chronic hypertension. The clinical features and consequences of
pheochromocytoma/paraganglioma result from the release of catecholamines (e.g.,
norepinephrine and epinephrine) by the tumor. If a pheochromocytoma/paraganglioma is
undetected, stimuli that normally would not pose a hazard, such as surgery, childbirth, or
general anesthesia, can evoke catecholamine secretion by the tumor, with clinically
significant and even catastrophic outcomes. The diagnosis of pheochromocytoma/paraganglioma
and its localization can be challenging, because measurements of plasma levels or urinary
excretion of catecholamines and their metabolites and radio-iodinated
metaiodobenzylguanidine (MIBG) scanning can yield false-negative results in patients
harboring the tumor. Computed tomographic (CT) and magnetic resonance imaging (MRI) lack
sufficient specificity. The molecular mechanisms by which genotypic changes predispose to
development of pheochromocytoma/paraganglioma remain unknown, even in patients with
identified mutations. Moreover, pheochromocytomas/paragangliomas in patients with hereditary
predispositions differ in terms of their growth, malignant potential, catecholamine
phenotype, and responses to standard screening tests such as glucagon stimulation and
clonidine suppression tests. This protocol focuses on molecular and genetic studies that may
elucidate the bases for predisposition to develop pheochromocytomas/paragangliomas and for
expression of different neurochemical phenotypes and malignant potentials, new imaging
approaches, based on [(18)F]-6F-dopamine ([(18)F]-6F-DA), and
[(18)F]-L-3,4-dihydroxyphenylalanine ((18)F]-DOPA) positron emission tomographic (PET)
scanning, [99m]Tc-methoxyisobutylisonitrile SPECT scintigraphy (99m Tc-MIBI), and new
biochemical diagnostic criteria, based on measurement of plasma metanephrines. We also want
to evaluate the benefits romidepsin pretreatment for uptake enhancement of [(123/131)I]-MIBG
in pheochromocytoma/paraganglioma tumors.
Observational
N/A
To investigate the use of radiopharmaceutical tracer, F(18)-FLT for PET/CT scan in evaluating cellular proliferative behavior of various genetically inherited and sporadic pheochromocytomas and paragagliomas in adult patients.
Karel Pacak, M.D.
Principal Investigator
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
United States: Federal Government
000093
NCT00004847
February 2000
Name | Location |
---|---|
National Institutes of Health Clinical Center, 9000 Rockville Pike | Bethesda, Maryland 20892 |
Johns Hopkins University | Baltimore, Maryland 21205 |