ParagangliomaJuly 8, 2015 -
Paragangliomas are rare tumors that grow in cells of the peripheral nervous system (i.e. the nerves outside the brain and spinal cord). The peripheral nervous system can be divided into the sympathetic and parasympathetic nervous systems. In this section, we will talk about paraganglioma of the sympathetic nervous system. These sympathetic paraganglioma may make too much adrenaline (parasympathetic paraganglioma do not). Adrenaline is a hormone that affects such bodily functions as heart rate, blood pressure, breathing, digestion, sweating, urination, and sexual arousal. Adrenaline is said to control the “fight or flight” response, or in other words, it gets your body ready to react to stressful situations. Adrenaline is normally released from the adrenal medulla when there is danger or an emergency situation. In addition to raising heart rate and blood pressure, adrenaline opens air passages to allow in more oxygen, and boosts the supply of oxygen and glucose (sugar) to the brain and muscle. Pheochromocytomas in the adrenal gland may produce both adrenaline and noradrenaline. However, only paragangliomas that occur in the organ of Zuckerkandl, which is found along the lower part of the aorta, can make adrenaline.
The remainder of paragangliomas are either non-functioning (i.e. do not make hormones) or produce noradrenaline only. Paragangliomas may secrete noradrenaline in an uncontrolled fashion and can cause serious health problems including stroke, heart attack, and even death. Some physicians call paraganglioma a “pharmacological time bomb” because of its danger.
Paragangliomas are also called extra-adrenal pheochromocytomas and these terms are often used interchangeably. Overall, it has been estimated that approximately 10% of pheochromocytomas occur in an extra-adrenal location. Compared to adrenal pheochromocytomas, paragangliomas have a higher risk of being malignant or cancerous, as high as 40-50% in some studies.7 Larger tumor size (over 5 cm), invasion of the tumor into adjacent structures, and spread (metastases) to other organs are characteristics of malignant paragangliomas.11
Paragangliomas may develop anywhere there are sympathetic nerve cells, and this usually means along any of the major arteries in the body. Paragangliomas can be found in the skull region, neck, chest cavity, abdomen, pelvis, and bladder. Far and away, the most common site is within the abdomen where approximately 85-90% are located. Most abdominal paragangliomas are found in front of or to the side of the vertebral column near the aorta or kidney. In contrast, the most common location for a parasympathetic paraganglioma is in the neck.
Most paragangliomas occur as sporadic tumors, that is, they are not inherited. However, certain hereditary syndromes such as von Hippel-Lindau syndrome and mutations in the succinate dehydrogenase (SDH) gene, and multiple endocrine neoplasia (MEN) type 2 can be associated with development of paragangliomas. (3) Paragangliomas may also occur simultaneously with pheochromocytomas and may occasionally occur as multiple tumors.
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