Case 12 Discussion | the-imaging-eye

Case 12

Contributors

Dr.Santosh Dasar Dr.Uthsavi

Diagnosis

Carotid Body Tumor

Radiological Findings, Disease course and Management

High Resolution Ultrasound and Color Doppler US of Neck

Findings

Well-defined solid echogenic mass in the right side of the neck.
Mass is in close proximity to the carotid bifurcation, widening the bifurcation and splaying the vessels.
Color Doppler demonstrates significant internal vascularity within the mass

CECT Neck with CT Angiogram Neck vessels

Findings

Well defined lobulated intense homogeneously enhancing soft tissue density mass lesion in the carotid space of neck on right side commencing at the level of bifurcation of common carotid artery.
The lesion splays the proximal portions of internal and external carotid arteries with encasement of the vessels. No evidence of thrombosis.
Superiorly,it extends upto the tip of styloid process.
Infero-medially,it compresses the parapharyngeal soft tissue with indentation over lateral wall of nasooropharyngeal airway with resultant luminal narrowing.
It measures 60mm (AP) x 55mm (ML) x 65mm (cranio-caudal)
Right submandibular gland is displaced antero-laterally,internal jugular vein is displaced postero-laterally and drapes around the mass.

Radiological Diagnosis

Right carotid body tumor or Paraganglioma.

Disease Course and Management

Excision biopsy of the lesion was performed and
Carotid body tumor was confirmed histopathologically.

Discussion

Carotid body tumour, is also known as a chemodectoma or carotid body paraganglioma
It is a highly vascular glomus tumour that arises from the paraganglion cells of the carotid body.
Location: at the carotid bifurcation with characteristic splaying of the ICA and ECA.
Age: 4th to 5th decades,
Gender: Has a female predilection
Features:

-Slow growing rounded neck mass,

-Usually located anterior to the sternocleidomastoid near the angle of the mandible at the level of the hyoid bone. -Can be moved side to side but not up or down, due to its location within the carotid sheath.

Diagnosis

Carotid body tumours are located at the carotid bifurcation with characteristic splaying of the ICA and ECA, described as the lyre sign.

Ultrasound

A well-defined solid mass in the neck, may be unilateral or bilateral.
Hypoechoic or may be mildly echogenic. Anechoic tubular channels representing small vessels may be seen within the mass.
Mass is seen in close proximity to the carotid bifurcation, widening the bifurcation and splaying the vessels. It can also compress or encase the common, external and/or internal carotid vessels.
Color Doppler shows significant internal vascularity within the mass in about 75% of all carotid body tumors. The feeding vessels mostly arise from the external carotid artery, the internal carotid and the vertebral artery may also supply the carotid body tumor.
Spectral analysis: low resistance flow may be seen within the mass.

soft tissue density on non-contrast CT (similar to muscle)
bright and rapid (faster than schwannoma) enhancement
splaying of the ICA and ECA

MRI

T1: iso to hypointense compared to muscle, salt and pepper appearance when larger, representing a combination of punctate regions of hemorrhage or slow flow (salt) and flow voids (pepper),intense enhancement following gadolinium
T2: hyper intense compared to muscle, salt and pepper appearance

DSA/angiography

Splaying of the carotid vessels (lyre sign) is identified with an intense blush in tumor with an 'early vein' seen due to arteriovenous shunting.
The ascending pharyngeal artery is the main contributing supply.

Scintigraphy

Shows uptake with metaiodobenzylguanidine (MIBG) and octreoscan scintigraphy.
Can be useful for assessing multiple lesions.

Complications

Rare: malignant transformation of the tumor with peri-neural and vascular invasion

Differential diagnosis

Vagal schwannoma: tends to displace both vessels together rather than splaying them
Vagal neurofibroma: tends to displace both vessels together rather than splaying them
Lymph node mass: may look similar if hypervascular
Glomus vagale tumour: same pathology but located more rostrally
Carotid bulb ectasia