Carotid body tumor

WikiDoc Resources for Carotid body tumor
Articles
Most recent articles on Carotid body tumor Most cited articles on Carotid body tumor Review articles on Carotid body tumor Articles on Carotid body tumor in N Eng J Med, Lancet, BMJ
Media
Powerpoint slides on Carotid body tumor Images of Carotid body tumor Photos of Carotid body tumor Podcasts & MP3s on Carotid body tumor Videos on Carotid body tumor
Evidence Based Medicine
Cochrane Collaboration on Carotid body tumor Bandolier on Carotid body tumor TRIP on Carotid body tumor
Clinical Trials
Ongoing Trials on Carotid body tumor at Clinical Trials.gov Trial results on Carotid body tumor Clinical Trials on Carotid body tumor at Google
Guidelines / Policies / Govt
US National Guidelines Clearinghouse on Carotid body tumor NICE Guidance on Carotid body tumor NHS PRODIGY Guidance FDA on Carotid body tumor CDC on Carotid body tumor
Books
Books on Carotid body tumor
News
Carotid body tumor in the news Be alerted to news on Carotid body tumor News trends on Carotid body tumor
Commentary
Blogs on Carotid body tumor
Definitions
Definitions of Carotid body tumor
Patient Resources / Community
Patient resources on Carotid body tumor Discussion groups on Carotid body tumor Patient Handouts on Carotid body tumor Directions to Hospitals Treating Carotid body tumor Risk calculators and risk factors for Carotid body tumor
Healthcare Provider Resources
Symptoms of Carotid body tumor Causes & Risk Factors for Carotid body tumor Diagnostic studies for Carotid body tumor Treatment of Carotid body tumor
Continuing Medical Education (CME)
CME Programs on Carotid body tumor
International
Carotid body tumor en Espanol Carotid body tumor en Francais
Business
Carotid body tumor in the Marketplace Patents on Carotid body tumor
Experimental / Informatics
List of terms related to Carotid body tumor

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 tumor 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. Carotid body tumors can be multicentric (35-50%) or familial (7-10%). In familial forms, carotid body tumors are usually autosomal dominant in inheritance, and associated with genetic syndromes. 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. Transcervical surgery approach in conjunction with embolisation are the most common approaches to the treatment of carotid body tumor.

Historical Perspective

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

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.

• Class I: localized with minimal vascular attachment
• Class II: partially surrounds carotids.
• Class III: encases carotids.

• The image below demonstrates the distribution of carotid body tumors.

• 

  Distribution of paraganglioma

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:

• Arranged in distinctive cell balls (zellballen)
• Separated by fibrovascular stroma and surrounded by sustentacular cells
• Positive for chromogranin, synaptophysin, neuron specific enolase, serotonin, neurofilament and neural cell adhesion molecule; they are S-100 protein negative.
• The sustentacular cells are S-100 positive and focally positive for glial fibrillary acidic protein.
• By histochemistry, the paraganglioma cells are argyrophilic, periodic acid Schiff negative, mucicarmine negative, and argentaffin negative.

• The images below demonstrate gross pathology and microscopic histopathological findings of the carotid body tumor.

• 

  Gross pathology of carotid body tumor

• 

  Carotid body tumor higher magnification

• 

  Carotid body tumor lower magnification

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:

• Vagal schwannoma
• Vagal neurofibroma
• Lymph node mass
• Glomus vagale tumour
• Carotid bulb ectasia
• Carotid calcification
• Branchial cleft cyst

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.

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.
• Common complications of carotid body tumor, include cranial nerve palsy, stroke, or Horner syndrome.
• 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 imaging findings:

• Lyre sign (see Imaging below)
• Early vein due to arteriovenous shunting
• Bright and rapid enhancement
• Family history of the following syndromes (tuberous sclerosis complex, neurofibromatosis type 1, and Von Hippel-Lindau disease)

Symptoms

• Carotid body tumor is usually asymptomatic.
• Symptoms of carotid body tumor may include the following:

• Dysphagia
• Swallowing difficulty
• Shortness of breath
• Lightheadedness
• Numbness in the tongue
• Weakness or pain in the shoulders
• Vision changes
• Drooping eyelid
• Heart palpitations

Physical Examination

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

Palpation

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

Inspection

• Limitation on neck range of motion
• Pharyngeal bulge with displacement of the tonsil, soft palate, and uvula to the opposite side

Auscultation

• Bruit
• 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

Gallery

• 

  MRA of carotid body tumor

• 

  Carotid body tumor angiography

• 

  CT scan of carotid body tumor.

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.