Carotid Body Tumor Microenvironment.

Carotid body tumors (CBTs) are rare paragangliomas, comprising 0.5% of all head and neck tumors, and 65% of head and neck paragangliomas. A majority of CBTs occur sporadically, while 15% are familial or hyperplastic in the setting of chronic hypoxia. They usually present as unilateral, well-circumscribed rubbery masses, arising at the level of the carotid bifurcation. A majority of CBTs are painless and therefore may evade diagnosis for months to years. Symptomatic lesions occur due to progressive cranial nerve IX, X, or XII dysfunction, manifesting as hoarseness, dysphagia, vertigo, coughing, or odynophagia. Other local symptoms include neck discomfort, pulsatile tinnitus, hearing loss, or carotid sinus syndrome. Appropriate workup includes a thorough physical exam followed by radiographic imaging, vascular studies, and biochemical workup with 24 h urinary catecholamine or metanephrine analysis. The management of these tumors, which involves standalone surgical resection or following embolization for larger and more vascular tumors, will also be discussed.