Paraganglioma pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Ahmad Al Maradni, M.D. [2]
Overview
Pathophysiology
Paragangliomas arise from the glomus cells, which are special chemoreceptors located along blood vessels that have a role in regulating blood pressure and blood flow. The main concentration of glomus cells are found in the carotid body (located in the upper neck at the branching of the common carotid artery), and the aortic bodies (located near the aortic arch). The glomus cells are a part of the paraganglion system composed of the extra-adrenal paraganglia of the autonomic nervous system, derived from the embryonic neural crest. Thus, paragangliomas are a type of neuroendocrine tumor, and are closely related to pheochromocytomas. Although all paragangliomas contain neurosecretory granules, only about 1-3% have clinical evidence of oversecretion.
Mutations of the genes SDHD (previously known as PGL1), PGL2, and SDHC (previously PGL3) have been identified as causing familial head and neck paragangliomas. Mutations of SDHB play an important role in familial adrenal pheochromocytoma and extra-adrenal paraganglioma (of abdomen and thorax), although there is considerable overlap in the types of tumors associated with SDHB and SDHD gene mutations.
Gross Pathology
The paragangliomas appear grossly as sharply circumscribed polypoid masses and they have a firm to rubbery consistency. They are highly vascular tumors and may have a deep red color.
Microscopic Pathology
On microscopic inspection, the tumor cells are readily recognized. Individual tumor cells are polygonal to oval and are arranged in distinctive cell balls, called Zellballen. These cell balls are separated by fibrovascular stroma and surrounded by sustentacular cells.