(A500) A case of carotid bifurcation vascular malformation masquerading as carotid body tumor

Introduction: The differential diagnosis for a carotid space mass can be narrowed using pathognomonic radiographic features and laboratory tests. Nevertheless, surgical exploration can yield an unexpected finding. We present a rare case of carotid bifurcation vascular malformation.

Methods: This is a case report and literature review. Multidisciplinary review of the case was performed. A literature review of carotid sheath masses was performed in PubMed Central.

Results: A 60-year-old woman presented to the ED with left facial paresthesia and sharp occipital pain. CT angiography revealed a 2.5cm mass at the left carotid bifurcation with internal calcifications and splaying of the internal and external carotid arteries. On MRI, the mass was enhancing, T1 hypointense, and T2 heterogeneously hyperintense with vascular signal voids, suggestive of carotid body tumor. Further, the patient recalled that her mother had a peri-brainstem mass, which she thought may have been a paraganglioma. Genetic testing for succinate dehydrogenase mutations returned negative. Twenty-four hour urine fractionated metanephrine testing was normal.
Patient wished to proceed with surgery. Intraoperatively the mass was amorphous, and frozen section suggested a vascular malformation. This was confirmed on final pathology, which showed a lesion comprising tortuous, bizarrely shaped, inter-anastomosing vasculature of variable caliber, with no neoplasm identified.
There are six prior reports of carotid sheath vascular malformation, two at the carotid bifurcation. Though surgical intervention is an option for these entities, as they often do not involute and can continue to grow, less invasive interventions are available. Additionally, it is noted in the literature that calcifications may be a radiologic feature more prevalent in slow-flow venous malformations than in other entities like paraganglioma.

Conclusions: Though rare, vascular malformations should be considered on the differential for carotid space masses, particularly in the presence of calcifications, best visualized on CT.