Glomus Tumor

A glomus tumor, or paraganglioma, is a rare, usually benign neoplasm arising from paraganglionic cells, which act as chemoreceptors. These cells normally detect changes in blood chemistry and are located along major blood vessels and nerves.

Although typically benign, these tumors can pose significant clinical challenges due to their location near vital structures, including cranial nerves and large blood vessels, and their rich vascular supply. Tumor growth is generally slow, but it may compress or damage adjacent tissues.

Aetiology and pathophysiology

Paragangliomas develop from neuroendocrine cells that are part of the autonomic nervous system. A substantial proportion of cases (up to 30–40%) are linked to inherited mutations, most commonly in the succinate dehydrogenase (SDH) genes.

Most head and neck glomus tumors are hormonally inactive. However, paragangliomas located in the abdomen may produce catecholamines (adrenaline and noradrenaline), leading to symptoms similar to those seen in pheochromocytoma.

Clinical Significance

The clinical manifestations of glomus tumors largely depend on their location.

• Glomus tympanicum (middle ear). Produces pulsatile tinnitus, in which the patient perceives their own heartbeat, and conductive hearing loss.
• Glomus jugulare (at the cranial base). Involves cranial nerves, leading to hoarseness, difficulty swallowing, and shoulder muscle weakness.
• Carotid body tumor. Presents as a slowly enlarging, painless mass in the neck at the carotid bifurcation.

Diagnosis is based on contrast-enhanced CT and MRI, which reveal a highly vascularized tumor. Treatment is complex and may involve surgical removal, with preoperative embolization often used to minimize intraoperative blood loss. Radiotherapy may be employed in some cases, or the patient may be managed with careful observation.