Paraganglioma

Ariane Staub Neish, MD
Amir Zamani, MD

July 12, 1995

Presentation

A 42-year-old woman presented with a neck mass.

Imaging Findings

Axial T1-weighted MRI

Axial T2-weighted MRI

MR Angiogram

Contrast-enhanced axial CT

On axial T1-weighted MRI without intravenous contrast, a 2-cm mass with intermediate signal intensity is visible in the left carotid space (long arrow). The mass displaces the external carotid artery (ECA) anteriorly and the internal carotid artery (ICA) posteriorly (short arrows). Several tiny flow voids are visible within the anterior third of the mass.

On axial T2-weighted MRI the 2-cm carotid space mass has a high signal intensity (arrow).

On the MR angiogram, the ECA and the ICA (arrow) are splayed. Multiple small vessels are visible within the region of the mass and appear to arise from a branch of the ECA (likely the ascending pharyngeal artery).

Axial CT with intravenous contrast enhancement demonstrates intense enhancement of the left carotid space mass (arrow).

Differential Diagnosis

The differential diagnosis for carotid space masses includes (1):

I.Pseudotumor: Ectatic common carotid artery/internal carotid artery; Asymmetric Internal Jugular Vein
II.Inflammatory: Abscess
III.Vascular: Jugular Vein Thrombosis; Carotid Aneurysm/Thrombosis; ICA Dissection
IV.Benign Tumor: Paraganglioma; Glomus Jugulare; Glomus Vagale; Carotid Body Tumor; Neural Sheath Tumor; Schwannomas; Neurofibromas; Meningiomas
V.Malignant Tumor: Squamous Cell Carcinoma; Non-Hodgkin's Lymphoma

Diagnosis

paraganglioma

Discussion

The prompt and intense contrast enhancement of this carotid space mass as well as the multiple tiny flow voids on MRI images favor the diagnosis of paraganglioma. The intense enhancement on the CT image is also characteristic. Paragangliomas are multiple in 3% to 5% of patients (the incidence rises to 20% to 30% in patients with a family history of the tumor)(2). The most common extra-adrenal sites for paragangliomas include common carotid artery (CCA) bifurcation, jugular bulb, middle ear (tympanicum) and nodose ganglion of the vagus nerve. Schwannomas do enhance but usually less intensely than paragangliomas. Degenerative cystic changes are often present. The slow expansile growth of schwannomas may cause smooth scalloping of adjacent bone, a feature that distinguishes them from paragangliomas (paragangliomas cause permeative destruction of bony structure). Furthermore, the flow voids within tiny vessels supplying the tumor are typical of paragangliomas although small paragangliomas (<2 cm) rarely have this feature. Unlike schwannomas, neurofibromas rarely have central degenerative cystic or necrotic changes (3).

References

1. Harnsberger HR. Head and neck imaging. Chicago: Year Book Medical Publishers, 1990:80.

2. Som PM, Bergeron RT. Head and neck imaging. St Louis: Mosby Year Book, 1991:443.

3. Som PM, Bergeron RT. Head and neck imaging. St Louis: Mosby Year Book, 1991:445.

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