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Vascular » Cerebrovascular
Carotid body tumor
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Author(s) :
P.K. Srivastava, MD
 
Presentation A 17 year old girl presents with a non-pulsatile neck mass of a hard consistency. An ultrasound of the neck was performed.
 
 
 
Caption: Transverse image of the mass in the neck
Description: There is a hypoechoic mass seen in the right side of the neck. It is seen in close proximity to the carotid artery.
 
 
 
Caption: Oblique image of the mass
Description: This oblique image also demonstrates the hypoechoic neck mass in close proximity to the right neck vessels. The mass per se shows no significant internal vascularity.
 
 
 
Caption: Transverse image of the right sided neck mass
Description: The mass appears to displace the internal jugular vein and the carotid artery anteriorly.
 
 
 
Caption: Oblique image of the right sided neck mass
Description: The heterogeneous mass is noted again.
 
Differential Diagnosis Carotid body tumor, an enlarged node
 
Final Diagnosis Carotid body tumor
 
Discussion Carotid body tumor may also be described as a chemodectoma, glomus tumor or a paraganglioma. It is a slow growing, benign tumor that is usually non-functioning. Aggressive behavior and malignant transformation of the tumor with peri-neural and vascular invasion is known to occur but is rare. 

Carotid body tumors are neuro-endocrine tumors that arise from the neural crest paraganglionic cells that are located at the level of the carotid bifurcation. These cells line the adventitia of the blood vessel. There may be a familial mode of inheritance. 

Many patients are asymptomatic or may present with laterally placed, slow-growing, soft masses in the neck. They may transmit the carotid pulsations and a bruit may be heard over the mass. Occasionally a patient may present with a hard and non-pulsatile mass. As the tumor enlarges, it may produce dysphagia/odynophagia or hoarseness. If the tumor is functioning, symptoms due to excessive production of catecholamines occur.

Imaging features: Neck ultrasound with color Doppler is a reliable modality to image the entire extent of carotid body tumors. The following features are commonly recognized on ultrasound:
1. A well-defined solid mass in the neck that may be unilateral or bilateral.
2. The mass is hypoechoic or may be weakly echogenic. Anechoic tubular channels representing small vessels may be seen within the mass.
3. The mass is seen classically in close proximity to the carotid bifurcation, widening the bifurcation and splaying the vessels. It may also appear to compress or encase the common, external and/or internal carotid vessels.
4. Color Doppler demonstrates significant internal vascularity within the mass in about 75% of all carotid body tumors. The feeders arise from the external carotid artery, although the internal carotid and the vertebral artery may also supply the carotid body tumor.
5.On spectral analysis, low resistance flow may be detected within the mass.

Some of the atypical features that may be seen in a carotid body tumor include:
1. The characteristic splaying of the carotids may not be seen.
2. The mass may be hypovascular or avascular.

The treatment of choice is surgical excision. A pre-operative biopsy is usually contraindicated [as these masses are typically very vascular and a biopsy may make adequate surgery difficult], and hence the importance of ultrasound in arriving at a diagnosis by demonstrating the classic location of the mass and its internal vascularity.
 
Case References 1. Niu L, Hao Y, et al. Sonographic diagnosis of carotid body tumor. Zhonghua Zhong Liu Za Zhi. 2002 Sep; 24(5):488-90.
2. Alkadhi H, et al. Evaluation of topography and vascularization of cervical paragangliomas by magnetic resonance imaging and color duplex sonography. Neuroradiology. 2002 Jan; 44(1):83-90.
3. Stoeckli SJ, et al. Evaluation of paragangliomas presenting as a cervical mass on color-coded Doppler sonography. Laryngoscope. 2002 Jan; 112(1):143-6.
4. Arslan H, Unal O, Kutluhan A, Sakarya ME. Power Doppler scanning in the diagnosis of carotid body tumors.  J Ultrasound Med. 2000 Jun; 19(6):367-70.
5. Schreiber J, Mann W, Ringel K. The role of color duplex ultrasound in diagnosis and differential diagnosis of carotid body tumors. Laryngorhinootologie. 1996 Feb; 75(2):100-4.
6. Barry R, et al. Duplex Doppler investigation of suspected vascular lesions at the carotid bifurcation. Ann Vasc Surg. 1993 Mar; 7(2):140-4.
 
Follow Up At surgery the tumor was seen to be arising from the carotid sheath, splaying the external and internal carotid artery. The vessel walls were intact and a biopsy confirmed the tumor to be a carotid body tumor. 
 
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