Genetically transmitted disorder characterized by the development of highly vascularized tumors derived from neuroectodermal cells, preferentially localized in the carotid body (80% of cases) and in the glomus jugulare (20% of cases).
Carotid Body Tumors; Chemodectomas; Glomus Jugulare Tumors; Hereditary Paraganglioma.
Familial paragangliomas, or glomus tumors, are slow growing, highly vascular, generally benign neoplasms, usually of the head and neck, that arise from neural crest cells outside of the adrenal medulla. Tumors arising in chemoreceptor structures include carotid body tumors and glomus jugulare tumors.
Glomus tumors accounts for only 0.03% of all neoplasms and 0.6% of head and neck tumors. They are sometimes familial, bilateral, and associated with other neoplasms. They can be malignant, although this is rare.
Inheritance is autosomal dominant. The paraganglioma gene PGL1 has been mapped to 11q22.3-q23. Germline missense mutations in the gene encoding succinate dehydrogenase subunit D (SDHD) gene have been identified. The disease is subject to age-dependent penetrance and imprinting.
Tumors may be bilateral or unilateral. The most common sites are the carotid body, the vagal body, and the jugulotympanic site. It is postulated that the tumor starts secondary to stimulus of hypercarbia or hypoxemia (the carotid bodies are the peripheral chemoreceptors that act as sensors for both hypoxia and hydrogen ion concentration). Others postulate that there is a connection between living at high altitude, emphysema, and carotid body tumors. There may be an association between paraganglioma and pheochromocytoma. The tumors have a tendency to reproduce the microscopic structure of the normal carotid body. These carotid body tumors are referred to as nonfunctional with regards to the nonchromaffin nature of the tumor, but chemoreceptor function is still present.
Most patients present for evaluation of an anterior neck mass discovered on clinical examination or self-examination or detected during duplex scanning for carotid artery disease. In patients with tympanic chemodectomas, the condition may be suspected because of tinnitus aurium and a transtympanic reddish image by otoscopy. Arteriography remains the gold standard for diagnosis. Doppler color flow imaging, dynamic angioscintigraphy, CT, and MRI contribute additional information about tumor extension.
Age at onset of symptoms was significantly different between fathers and children (affected children have earlier age of onset). Clinical manifestations depend on tumor location and are often related to the middle ear (pulsatile tinnitus, conductive hearing loss, aural fullness, discharge or bleeding, and a bluish mass behind the tympanic membrane are characteristic). Cranial nerve dysfunctions (facial paralysis, dysphonia, marked hearing loss, pain) are associated with the clinical presentation. The most common complaint was swelling in the anterolateral region of the neck. Familial carotid body tumors tend to be multiple. ...