Discussion of Pheochromocytoma
- Pheochromocytomas are rare catecholamine-secreting tumors.
- A major impetus for the noninvasive diagnosis of pheochromocytomas is that any physical contact with these neoplasms can precipitate cardiac arrhythmias and malignant hypertension.
- More than 90% of pheochromocytomas are located within the adrenal glands.
- 98% occur within the abdomen.
- Extraadrenal pheochromocytomas develop in paraganglionic chromaffin tissue of the sympathetic nervous system. They may occur anywhere from the base of the brain to the urinary bladder and are considered to be paragangliomas.
- Common locations for extraadrenal pheochromocytomas include:
- Organ of Zuckerkandl
- Bladder wall
- Carotid and glomus jugulare bodies
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- Pheochromocytomas can be bilateral and malignant in 10% of patients.
- About 10% of pheochromocytomas were thought to be hereditary. These mutations may be seen in isolation (94% of cases) or as part of a syndrome—for example, multiple endocrine neoplasia (MEN) II and III and various neuroectodermal disorders including neurofibromatosis, von Hippel–Lindau syndrome, Sturge-Weber syndrome, and Carney triad.
 Imaging Findings for Pheochromocytoma
- Pheochromocytomas and paragangliomas can have almost any imaging appearance
- Pheochromocytomas may be homogeneous or heterogeneous, solid or cystic complex masses or may show calcification
- Pheochromocytomas typically enhance avidly but can be heterogeneous or show regions of no enhancement due to cystic changes
- Most common MR imaging appearance of pheochromocytoma is a mass with low signal intensity at T1-weighted imaging and with high signal intensity at T2-weighted imaging.
- Pheochromocytomas commonly enhance avidly at T1-weighted imaging after administration of gadolinium-based contrast material
- I-131 MIBG has almost 100% specificity but limited sensitivity.
- Somatostatin receptor scintigraphy performed with In-111 OctreoScan, an analogue of somatostatin, provides another method for localizing pheochromocytoma. However, a conventional dose of octreotide enables localization of pheochromocytoma in less than 30% of cases
Patient #1: Bladder pheochromocytoma
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 References for Pheochromocytoma
- Michael A. Blake, Mannudeep K. Kalra, Michael M. Maher, Dushyant V. Sahani, Ann T. Sweeney, Peter R. Mueller, Peter F. Hahn, and Giles W. Boland. Pheochromocytoma: An Imaging Chameleon. RadioGraphics 2004 24: S87-99S.