Carotid body tumour
- Paragangliomas of the head and neck at carotid bifurcation → splays ICA & ECA (“lyre sign”).
- Often bilateral/multiple (esp. familial). So, bilateral carotid body tumours → think SDHx workup.
- Shamblin class (I–III) based on degree of carotid encasement → correlates with surgical difficulty.
Differential diagnosis
By location (carotid space)
- Vagal schwannoma
- Often less vascular, may cause smooth fusiform expansion along nerve with cystic change, no intense early enhancement.
- Hypervascular nodal metastases (e.g. thyroid, RCC)
- Nodal distribution, clinical context of primary malignancy.
- Lack classic splaying/displacement pattern.