Carotid body tumours
Tumour arising from chemoreceptors at the bifurcation of the carotid artery.
More common in people living at high altitude; it is thought that longterm hypoxia is a predisposing factor.
Carotid body tumours are hormonally inactive chemodectomas arising from the chemoreceptor tissue of the common carotid artery at the level of the bifurcation of the artery into internal and external carotid body (anatomically at the level of the hyoid bone). The tumour tends to grow upwards towards the skull base.
Patients present with a pulsatile swelling in the upper neck at the medial border of the sternocleidomastoid muscle. Classically on palpation the lump is mobile from side to side but not up and down, and there may be an associated overlying carotid bruit. It is important to distinguish the rare carotid body tumour from the more common metastatic lymph node from a head and neck tumour, which may have transmitted pulsation. Metastasis of carotid body tumours is very rare.
The tumour has a rich blood supply. It is composed of chief cells with clear cytoplasm and a round nucleus en-closed in a fibrous tissue framework.
Angiography shows a splaying of the carotid bifurcation (lyre sign). CT and MRI imaging demonstrate the tumour.
Surgical excision may be performed especially in young healthy patients. In elderly patients surgical removal may not be necessary.