Pathophysiology
Clinical meaning
Carotid body tumors, also known as carotid body paragangliomas or chemodectomas, are rare neuroendocrine neoplasms arising from the paraganglia of the carotid body, a small chemoreceptor organ located at the bifurcation of the common carotid artery into the internal and external carotid arteries. The carotid body is a highly vascularized structure approximately 3-5 mm in diameter that functions as the primary peripheral chemoreceptor for detecting changes in arterial blood oxygen tension (PaO2), carbon dioxide tension (PaCO2), and pH. It plays a critical role in the physiological response to hypoxemia by triggering reflexive increases in respiratory rate, heart rate, and blood pressure through afferent signaling via the glossopharyngeal nerve (cranial nerve IX) to the brainstem respiratory and cardiovascular centers. The carotid body contains two primary cell types: type I (glomus) cells, which are the chemosensory cells derived from neural crest progenitors, and type II (sustentacular) cells, which are supporting glial-like cells that surround and sustain the glomus cells. Type I glomus cells are the cells of origin for carotid body paragangliomas. These cells contain dense-core neurosecretory granules filled with catecholamines (primarily...