Carotid glomic tumor: diagnosis by MRI, arteriography and histology

Clinical History

A 66-year-old woman was admitted to our hospital complaining about a lateral cervical mass.

Imaging Findings

A 66-year-old woman was admitted to our hospital complaining about a lateral cervical mass. First she underwent an ultrasound which showed an hypervascular solid mass in the carotid common biforcation (44x45 mm). Then we performed an MR angiography which confirmed the presence of a right parafaringeal lesion at the common carotid fork level. After injection of contrast material, it enhanced significantly. Angiography confirmed an expensive mass within the fork of the common carotid vassel and with an early and homogeneus enhancement fed by collateral vessels of right external carotid. Besides it compressed and dislocated forward the internal and external carotid vessels. The patient underwent surgical resection of this mass. The histological diagnosis was: paraganglioma positive for chromogranin, synaptophysin and s-100 protein, negative for citocheratin.

Discussion

Paragangliomas of the head and neck originate from the paraganglia or glomus cells within the carotid body, vagal nerve, middle ear, jugular foramen, and many other locations. They are usually considered benign but about 3% of them metastatizes to lymphonodes or to common sites like lung and bone. The carotid body tumor has a peak occurence at the age of 45–50 years. The mass is pulsatile, mobile in the lateral plane but limited in the cephalocaudal direction. Occasionally it may transmit the carotid pulse and it is associated with a bruit. It usually presents as a painless neck mass but larger tumors may cause cranial nerve palsies ( hypoglossal and vagus nerve). Other symptoms include hoarseness, stridor, tongue paresis, vertigo, and mild dysphagia. Although the large majority of carotid paragangliomas are non-functional, any symptoms of catecholamine secretion of the tumor should be sought. Histology of carotid paraganglioma is characterized by oval cells arragged in cell balls (called Zellballen) and separated by fibrovascular stroma. US is the best in the detection and follow up of cervical paragangliomas. Duplex Doppler imaging and color Doppler imaging demonstrate the intrinsic hypervascularity of the cervical paraganglioma and the characteristic splaying of the common carotid bifurcation tumors. The characteristic appearance of this tumor is a round-to-oval, well-defined, heterogeneously hypoechoic solid mass in the lateral neck. The typical CT appearance is a well-defined soft-tissue mass within the carotid space. The underlying hypervascularity results in homogeneous and intense enhancement following intravenous administration of contrast material. Paragangliomas typically exhibit a low signal intensity with standard spin-echo short repetition time (TR)/short echo time (TE) and long TR/short TE sequences and a high signal intensity with long TR/long TE sequences. As with CT, a homogeneous and intense pattern of enhancement is noted following the intravenous administration of contrast material. Multiple serpentine and punctate areas of signal void (salt-and-pepper a appearance) characterize the typical paraganglioma in all MR sequences. In fact the "pepper" component represents the multiple areas of signal void interspersed with the "salt" component seen as hyperintense foci (due to slow flow or hemorrhage) on both short TR and long TR images. MR angiography may be useful in defining the flow-related enhancement of feeding vessels in lesions larger than 1.5 cm. Besides MR imaging can depict paragangliomas that are smaller than 5 mm, whereas CT demonstrates only lesions greater than 8 mm. Skull base paragangliomas demonstrate the "drop-out phenomenon" seen after the intravenous administration of high-dose gadolinium with dynamic flow-related, computer-generated, time–versus–signal intensity curves. The typical angiographic appearance of a paraganglioma is that of a hypervascular mass with enlarged feeding arteries, intense tumor blush and early draining veins. Digital subtraction angiography is the most reliable preoperative imaging study for assessing ICA invasion, which is characterized by vessel narrowing and irregularity. However, digital subtraction angiography demonstrates the vascular supply (feeding vessels and collateral supply) of a paraganglioma , the relationship of the mass to the ICA and IJV, and the patency of the IJV (which is frequently thrombosed in larger paragangliomas). The main treatments are surgery, embolization and radiotherapy. Surgical excision is the treatment of choice although radiation therapy is an option for patients who are not surgical candidates.

Differential Diagnosis List

Final Diagnosis

Paraganglioma of the right common carotid vessel.

URL:	https://eurorad.org/case/6372
DOI:	10.1594/EURORAD/CASE.6372
ISSN:	1563-4086