Vascular Tumors of the Head and Neck

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What are paragangliomas and from which tissues do they arise?

Paragangliomas (PGLs) are slow-growing neuroendocrine neoplasms derived from paraganglia cells. These cells are extra-adrenal neuroectoderm-derived cells located in the adventitia of blood vessels. Paraganglia in the head and neck are typically related to the parasympathetic system, classified as nonchromaffin, non-catecholamine-secreting cells. Paraganglia related to the sympathetic system are classified as chromaffin, catecholamine-secreting neoplasms and are more common outside of the head and neck.

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How are head and neck PGLs different than PGLs outside of the head and neck?

The most common site of involvement is the adrenal medulla (pheochromocytoma, 90%), followed by the abdomen (8.5%), the thorax (1.2%), and the head and neck (0.3%). Head and neck PGLs are typically nonsecreting neoplasms with less than 1% producing catecholamines.

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What is the current standard terminology for head and neck PGLs?

PGLs have previously been referred to as carotid body tumors, nonchromaffin tumors, chemodectomas, glomus tympanicum, and glomus jugulare. Glomus is the most frequently misused term in the literature as it is technically a term for a histologically different benign cutaneous tumor. Proper nomenclature classifies head and neck PGLs based on anatomic location (e.g., carotid body, vagal, jugulotympanic paragangliomas).

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What are carotid body PGLs and what are their typical characteristics?

The carotid body is the largest, most compact collection of paraganglia in the body. Carotid body PGL is the most common in the head and neck, accounting for 60% of cases. Due to the physiologic function of the carotid body as a chemoreceptor, PGLs were known as chemodectomas. Although the term chemodectoma has been used in connection with all PGLs, it only applies to carotid body PGLs because the carotid body and aortic body are the only paraganglia that act as chemoreceptors. Carotid body PGLs typically present in the fifth or sixth decade of life, although hereditary forms tend to present 1 or 2 decades earlier, often by age 30 to 40. Bilateral tumors are found in 10% to 25% of cases.

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What is a major recognized risk factor for the development of a PGL?

Chronic hypoxia has long been recognized as a significant risk factor for development of a PGL. Interestingly, there is a dose-dependent relationship between incidence and altitude. At higher altitudes, female predominance is markedly elevated at 8:1 compared to 3:1 at lower altitudes.

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What are the two major types of middle ear PGLs?

Middle ear PGLs are commonly referred to as glomus jugulare and glomus tympanicum tumors and account for 30% of head and neck PGLs. They typically present in the sixth decade of life. Jugular neoplasms arise from jugular bulb paraganglia along the medial promontory wall, whereas tympanic neoplasms arise from paraganglia associated with Jacobson’s nerve. Jugular neoplasms tend to invade the petrous bone and their growth leads to bony destruction. Tumors of the jugular foramen can result in cranial IX to XI nerve dysfunction, and resection in this region involves a combined skull base procedure that can result in significant cranial nerve–related morbidity.

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What are vagal PGLs? What are laryngeal PGLs?

Vagal PGLs arise from the inferior vagal ganglion (nodose ganglion) in the vagal trunk approximately 2 centimeters distal to its exit from the brainstem, although they can also arise from the superior vagal ganglion. These tumors comprise 10% of head and neck PGLs. Tumors associated with peripheral vagus nerve branches are categorized based on their anatomical locations. Laryngeal PGLs are very rare neoplasms derived from the superior or inferior paraganglia of the larynx. Laryngeal PGLs are most often located in the supraglottis and are more common in women.

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How do head and neck PGLs present?

Head and neck PGLs are typically asymptomatic and are frequently discovered incidentally on imaging. All PGLs demonstrate a female predominance. Carotid body PGLs typically present with a pulsatile neck mass that is mobile in the horizontal direction but limited vertically – an exam finding known as Fontaine’s sign. They occur near the anterior border of the sternocleidomastoid muscle and the angle of the mandible and are rubbery and well-circumscribed upon palpation. The growth rate is estimated at 5 millimeters per year. Vagal PGLs can present with Fontaine’s sign but are generally not pulsatile, although they can transmit pulsations. These tumors commonly present with an ipsilateral Horner’s syndrome or vocal cord paralysis. A comprehensive cranial nerve exam is critical for all patients with head and neck PGLs. Middle ear PGLs commonly present with pulsatile tinnitus, hearing loss, and aural fullness, and larger tumors can present with lower cranial nerve involvement (cranial nerves IX, X, and XI). Tympanic PGLs can be visualized on otoscopy as a vascular mass behind or protruding through the eardrum. Laryngeal PGLs present with symptoms of laryngeal obstruction, including shortness of breath, hoarseness, and stridor.

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