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:*Bright and rapid (faster than schwannoma) enhancement
:*Bright and rapid (faster than schwannoma) enhancement
:*Splaying of the internal carotid artery and external carotid artery.
:*Splaying of the internal carotid artery and external carotid artery.
*Radiological signs for carotid body tumor, include:
:*'''Lyre sign''' : defined as the splaying of the internal and external carotid by a carotid body tumour (visible on CT angiography)


*On MRI, findings of carotid body tumor, include:  
*On MRI, findings of carotid body tumor, include:  

Revision as of 21:45, 8 April 2016

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Maria Fernanda Villarreal, M.D. [2]

Synonyms and keywords: Tumor of the carotid body;

Overview

Carotid body tumor (also known as carotid body paraganglioma) is a highly vascular glomus tumour that arises from the paraganglion cells of the carotid body. It is located at the carotid bifurcation with characteristic splaying of the internal carotid artery and external carotid artery. Carotid body tumor is classified into 3 categories: familial carotid body tumor, sporadic carotid body tumor, and hyperplastic carotid body tumor. The pathogenesis of carotid body tumor is characterized by the overgrowth from chemoreceptor paraganglioma cells. The genetic mutations associated with the development of carotid body tumor, include: MEN 2A, MEN 2B, and chromosome 3p25.5. Common causes of carotid body tumor, include: multiple endocrine neoplasia, phakomatoses, tuberous sclerosis complex (TS), neurofibromatosis type 1 (NF1), Von Hippel-Lindau disease (vHL), and the Carney triad. The estimated prevalence of carotid body tumor is approximately 1-2 cases per 100,000 individuals worldwide. Patients with carotid body tumor may be initially asymptomatic. Early clinical features include painless neck mass, dysphagia, and limited range of motion in the neck. If left untreated, the majority of patients with carotid body tumor may progress to develop neurological complications.[1]

Historical Perspective

  • Carotid body tumor was first described by Bungeler in 1952.[2]

Classification

  • Carotid body tumor is classified into 3 categories:
  • Familial carotid body tumor
  • Sporadic carotid body tumor
  • Hyperplastic carotid body tumor
  • Carotid body tumor is sub-classified into 2 categories:
  • Single
  • Bilateral
  • Carotid body tumor may also be classified according to Shamblin surgical classification into 3 subtypes: I, II, and III. [3]
  • Class I: localized with minimal vascular attachment
  • Class II: partially surrounds carotids.
  • Class III: encases carotids.

Pathophysiology

  • The pathogenesis of carotid body tumor is characterized by the overgrowth from chemoreceptor paraganglioma cells.
  • Carotid body tumors are normally located in the medial aspect adventitia of the carotid bifurcation.
  • The genetic mutations associated with the development of carotid body tumor, include:
  • MEN 2A
  • MEN 2B
  • Chromosome 3p25.5
  • On gross pathology, characteristic findings of carotid body tumor, include:
  • Dusky color
  • Highly vascular mass
  • On microscopic histopathological analysis, characteristic findings of carotid body tumor, include:
  • The images below demonstrate gross pathology and microscopic histopathological findings of the carotid body tumor.

Causes

  • Common causes of carotid body tumor, include:
  • Multiple endocrine neoplasia
  • Phakomatoses
  • Tuberous sclerosis complex (TS)
  • Neurofibromatosis type 1 (NF1)
  • Von Hippel-Lindau disease (vHL)
  • Carney triad

Differentiating Carotid Body Tumor from Other Diseases

  • Carotid body tumor must be differentiated from other diseases that cause rounded neck mass, limited range of head motion, and dyspnea such as:[6]
  • Vagal schwannoma
  • Vagal neurofibroma
  • Lymph node mass
  • Glomus vagale tumour
  • Carotid bulb ectasia

Epidemiology and Demographics

  • The prevalence of carotid body tumor is approximately 65% of all head and neck paraganglioma.
  • The estimated prevalence of carotid body tumor is approximately 1-2 cases per 100,000 individuals worldwide.
  • The incidence of carotid body tumor was estimated to be 0.012 cases per 100,000 individuals worldwide.[7]

Age

  • Carotid body tumor is more commonly observed among patients aged 40 to 50 years old.
  • Carotid body tumor is more commonly observed among adults.

Gender

  • Females are more commonly affected with carotid body tumor than males.

Race

  • There is no racial predilection for carotid body tumor.

Risk Factors

  • Common risk factors in the development of carotid body tumor, include:
  • Genetic mutations in the following genes:
  • MEN 2A
  • MEN 2B
  • Chromosome 3p25.5

Natural History, Complications and Prognosis

  • Patients with carotid body tumor may be initially asymptomatic.
  • Early clinical features include painless neck mass, dysphagia, and limited range of motion in the neck.
  • If left untreated, the majority of patients with carotid body tumor may progress to develop neurological complications.[1]
  • Common complications of carotid body tumor, include cranial nerve palsy or stroke.[1]
  • Prognosis is generally poor, and the average 5 year survival rate of patients with carotid body tumor is approximately 25-40%.

Diagnosis

Diagnostic Criteria

  • The diagnosis of carotid body tumor is made with the following diagnostic criteria:
  • Lyre sign (see Imaging below)
  • [criterion 2]
  • [criterion 3]
  • [criterion 4]

Symptoms

  • Carotid body tumor is usually asymptomatic.
  • Symptoms of carotid body tumor may include the following:
  • Dysphagia
  • Swallowing difficulty
  • Shortness of breath
  • Lightheadedness

Physical Examination

  • Patients with carotid body tumor usually appear pale or diaphoretic.
  • Physical examination may be remarkable for:

Palpation

  • Palpable painless mass
  • Enlarged anterior cervical or lateral cervical lymph nodes

Inspection

  • Limitation on neck range of motion
  • Neck bulging

Auscultation

  • Carotid murmur

Laboratory Findings

  • There are no specific laboratory findings associated with carotid body tumor.
  • In some cases, genetic testing may be useful for the detection of familiar syndromes related with carotid body tumors.

Imaging Findings

  • Enhanced CT is the imaging modality of choice for carotid body tumor.
  • On CT scan, carotid body tumor is characterized by the following findings:
  • Soft tissue density on non-contrast CT (similar to muscle)
  • Bright and rapid (faster than schwannoma) enhancement
  • Splaying of the internal carotid artery and external carotid artery.
  • Radiological signs for carotid body tumor, include:
  • Lyre sign : defined as the splaying of the internal and external carotid by a carotid body tumour (visible on CT angiography)
  • On MRI, findings of carotid body tumor, include:
  • T1: iso to hypointense compared to muscle
  • Salt and pepper appearance when larger, representing a combination of punctate regions of haemorrhage or slow flow (salt) and flow voids (pepper)
  • Intense enhancement following gadolinium
  • T2: hyper intense compared to muscle
  • Salt and pepper appearance also seen on T2

Other Diagnostic Studies

  • Carotid body tumor may also be diagnosed using angiogram
  • Findings on angiogram may include:
  • Vascular blush
  • Splaying of the carotids

Treatment

Medical Therapy

  • There is no treatment for carotid body tumor; the mainstay of therapy is supportive care.
  • Radiotherapy is the treatment of choice for patients without surgery fitness (poor surgical candidates)

Surgery

  • Surgery is the mainstay of therapy for carotid body tumor.
  • Transcervical surgery approach in conjunction with embolisation are the most common approaches to the treatment of carotid body tumor.
  • Stage III Shamblin carotid body tumors (greater than 5 cm) are eligible for surgery only.
  • The most common surgical complications of carotid body tumors is injury of the superior laryngeal nerve

Prevention

  • There are no primary preventive measures available for carotid body tumor.

References

  1. 1.0 1.1 1.2 Sen I, Stephen E, Malepathi K, Agarwal S, Shyamkumar NK, Mammen S (2013). "Neurological complications in carotid body tumors: a 6-year single-center experience". J. Vasc. Surg. 57 (2 Suppl): 64S–8S. doi:10.1016/j.jvs.2012.06.114. PMID 23336858.
  2. Zak, Hyams, and Lawson, The Paraganglionic Chemoreceptor System: Physiology, Pathology and Clinical Medicine.
  3. Arya S, Rao V, Juvekar S, Dcruz AK (2008). "Carotid body tumors: objective criteria to predict the Shamblin group on MR imaging". AJNR Am J Neuroradiol. 29 (7): 1349–54. doi:10.3174/ajnr.A1092. PMID 18417602.
  4. Carotid body tumor. Dr Yuranga Weerakkody and Assoc Prof Frank Gaillard et al. Radiopaedia 2015. http://radiopaedia.org/articles/carotid-body-tumour. Accessed on December 7, 2015
  5. 5.0 5.1 Carotid body tumor. Wikipedi 2015. Accessed on November 23, 2015. https://en.wikipedia.org/wiki/Paraganglioma#/media/File:Carotid_body_tumour_2_low_mag.jpg
  6. Carotid body tumor. Dr Henry Knipe. Radiopedia. http://radiopaedia.org/articles/carotid-body-tumour Accessed on April 8, 2016
  7. Grotemeyer D, Loghmanieh SM, Pourhassan S, Sagban TA, Iskandar F, Reinecke P, Sandmann W (2009). "[Dignity of carotid body tumors. Review of the literature and clinical experiences]". Chirurg (in German). 80 (9): 854–63. doi:10.1007/s00104-009-1724-x. PMID 19458915.