Carotid Body Tumor

David Goldemund M.D.
Updated on 06/01/2024, published on 21/11/2021

  • the carotid body tumor (glomus tumor) is a rare tumor, but it represents the most common extra-adrenal paraganglioma
    • more common in females, typically diagnosed in the 4th to 5th decade of life
    • most cases are sporadic; 10% are hereditary
      • familial tumors present earlier (typically in the 4th decade) and are more frequently multicentric
      • association exists with multiple endocrine neoplasia ( MEN IIa and MEN IIb), tuberous sclerosis complex (TS), neurofibromatosis type 1 (NF1), von Hippel-Lindau disease (vHL)
    • bilateral occurrence is observed in ~ 10% of cases
    • histologically similar tumors can also originate from the jugular bulb, sympathetic vagal ganglia of the neck (glomus vagale tumor  Glomus vagale tumor on MRA ), Jacobsen’s tympanic plexus of the middle ear, retroperitoneal sympathetic and visceral parasympathetic ganglia. Spinal paragangliomas are rare and occur intradurally extramedullary, usually in the region of the filum terminale/cauda equina, or less frequently, extradurally
  • hypervascularization is a hallmark feature of glomus tumors
  • due to the absence of neuroendocrine secretion, they are classified as chemodectomas (chemoreceptor tumors)
    • in sporadic cases, catecholamine secretion and associated hypertensive symptoms may be present
  • most head and neck paragangliomas are benign yet locally invasive
    • approximately 2–13% of paragangliomas demonstrate malignancy
    • malignancy is defined by metastasis, as there are no histopathologic criteria that can accurately differentiate malignant from benign paragangliomas
    • metastases are usually regional (in the neck); distant metastases are rare  (Boedeker, 2007)


To assess the extent and operability of tumors and to predict postoperative morbidity, the Shamblin Classification is used:

Shamblin I small, easily removable tumors
Shamblin II medium-sized tumors adhering to the carotid artery
Shamblin III tumors > 5 cm in size with transmural expansion into the carotid artery requiring resection of the affected arterial segment and its replacement  Carotid body tumor (Shamblin III)
Shamblin groups

Clinical presentation

  • most often, the tumor presents as a painless, elastic, pulsating, slowly growing rounded mass in the neck (located anterior to the sternocleidomastoid muscle, near the mandibular angle)
  • larger tumors cause head/neck pain, dysphonia, and other symptoms resulting from the involvement of multiple cranial nerves (CN IX, X, XI, and XII)
  • upon palpation, the mass moves horizontally but not vertically due to its fixation at the CCA bifurcation (Fontaine’s sign)
  • endocrine activity is less common compared to adrenal paragangliomas (pheochromocytomas)
Carotid body tumor (Poprachová, 2012)

Diagnostic evaluation



  • the tumor exhibits soft tissue density with rapid enhancement
  • as the tumor grows, a splaying of the origin of ICA and ECA  occurs  (“lyra” sign) Carotid body tumor on CT with post-contrast enhancement

    • tumors of glomus vagale or jugulare are located distally   Glomus vagale tumor on CTA
  • CTA shows a hyper-vascularized mass at the carotid bifurcation with early venous filling due to arteriovenous shunting   Carotid body tumor on CTA
  • the maximum circumferential contact of the tumor with the ICA on axial images can predict the Shamblin group  (Arya, 2008)

    • group I: <180 degrees of encasement
    • group II: 180-270 degrees of encasement
    • group III: >270 degrees of encasement (probable adventitial involvement necessitating ICA resection
  • T1
    • iso- to hypointense lesion with intense gadolinium enhancement  Carotid body tumor on MRI with post-contrast enhancement
    • the maximum circumferential contact of the tumor with the ICA on axial images can predict the Shamblin group
  • T2
    • “salt and pepper” appearance  Carotid body tumor on T2
Carotid body tumor on CTA

Carotid body tumor - T2 coronar

Carotid body tumor on MRA


  • hypervascularized mass in the carotid bifurcation   Carotid body tumor on ultrasound
Carotid body tumor on CTA and ultrasound (color flow mode)


  • splaying of the carotid vessels (lyra sign)
  • early venous filling due to arteriovenous shunting  Carotid body tumor on DSA with early vein filling

Functional imaging

  • a significant advantage of functional (metabolic) imaging is its capability to examine the entire body – useful for detecting multifocal or metastatic disease
  • 123I-metaiodobenzylguanidine (123I-MIBG) scintigraphy
    • suitable for detecting multiple lesions
    • applicable only in patients with hormonally active tumors
  • 111In-pentetreotide (148 MBq) scintigraphy –  utilizes a radiolabeled somatostatin analog that preferentially binds to the somatostatin receptor type 2 (SST2), which is highly expressed in paragangliomas

    • superior to 123I-MIBG scintigraphy for diagnosing and localizing chemodectomas (Muros, 1998)
    • applicable in hormonally inactive tumors
  • 18F-FDG PET – sensitive but not specific for CBT
    • effective for the detection of metastatic disease

Laboratory studies

  • monitoring of plasma levels of catecholamines and their metabolites in urine
    • due to the absence of endocrine secretion in the vast majority of carotid glomus tumors, this is important for differential diagnosis

If a glomus tumor is suspected, a biopsy should not be performed due to the tumor’s strong vascularization and high risk of bleeding

Differential diagnosis

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  • carotid body tumors are generally considered radioresistant + tumors treated primarily with radiation become difficult to resect (due to radiation-induced fibrosis) ⇒ therefore, surgery is the treatment modality of choice
  • the primary objective of radiotherapy is to slow disease progression
    • radiotherapy is reserved for large or multicentric tumors in patients with surgical contraindications  or unfavorable balloon test occlusion (BTO) findings
    • radiotherapy may also serve as an adjuvant following incomplete extirpation


  • in most cases, a complete cure is achievable with surgery
  • risk of recurrence ~ 10%
  • tumor growth is slow; therefore, long-term survival is possible even with advanced tumors – an annual mortality rate of <8% has been reported in untreated patients
  • cranial nerve damage resulting from tumor compression is usually irreversible
  • follow-up MRI is recommended due to the risk of recurrence or late metastases

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Carotid Body Tumor