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Carotid body tumour (cervical paraganglioma)

A carotid body tumour is a paraganglioma at the carotid bifurcation, presenting as a painless neck mass that moves side to side but not up and down and splays the internal and external carotid arteries apart; no biopsy is done, genetic testing is done (SDH mutations), and the main treatment is surgical excision, whose risk rises the more the tumour encases the arteries (Shamblin).

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Why it matters in the exam

The exam describes a mass in the side of the neck, below the angle of the jaw, sometimes pulsatile with a bruit over it. The tumour arises from the chemoreceptor cells of the carotid body, and is linked to high altitude and chronic hypoxia. A substantial share of cases are hereditary — mainly mutations in SDH genes (for example SDHD, in which tumours are often multiple and bilateral) — so genetic testing is recommended for all patients. Most tumours are non-secreting, but plasma metanephrines (and 3-methoxytyramine) are checked before surgery, because a secreting tumour needs pharmacological preparation. Needle biopsy is forbidden because of bleeding risk and the result does not help. On CT or MRI a highly vascular tumour splaying the ICA from the ECA is seen (the "lyre sign"), and in hereditary cases further tumours are sought with Ga-68 DOTATATE PET.

The Shamblin classification predicts surgical difficulty: I — a small tumour easily separated from the arteries; II — partially encasing the arteries; III — completely encasing them, sometimes requiring carotid resection and reconstruction. Surgery is done in the plane beneath the outer layer of the artery, and preserving the cranial nerves is a central challenge — the hypoglossal (XII), vagus (X) and glossopharyngeal (IX) nerves. For large tumours some centres perform preoperative embolisation to reduce bleeding. In bilateral tumours both sides are not resected in the same operation, and bilateral resection is approached with caution altogether, because bilateral baroreflex injury causes severe blood pressure swings. Malignancy is defined by metastases (to nodes or distant organs) and occurs in a minority of cases. In older patients, unresectable tumours or high surgical risk, radiotherapy is an alternative that stabilises the tumour.

A small asymptomatic tumour in a very old patient can be observed, because growth is usually slow.

Key points

• Paraganglioma at the carotid bifurcation.
• Lyre sign; moves side to side only.
• No biopsy; genetic testing for all.
• Shamblin I–III predicts difficulty.
• Cranial nerves at risk — XII, X, IX.

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Sources

• Endocrine Society Clinical Practice Guideline: Pheochromocytoma and paraganglioma, 2014 — Diagnosis and genetic testing
• NCCN Clinical Practice Guidelines in Oncology: Neuroendocrine and Adrenal Tumors, 2025 — Pheochromocytoma and paraganglioma
• Rutherford's Vascular Surgery and Endovascular Therapy, 10th edition (2022) — Carotid body tumors

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.