Question

A 50-year-old patient presents with a slowly growing, painless neck mass at the angle of the mandible. “Lyre's sign” is observed. What is the most likely diagnosis?

• A. Thyroid nodule
• B. Lymphadenopathy
• C. Carotid body tumor
• D. Branchial cyst

Hint:

Neck mass at carotid bifurcation with Lyre's sign = carotid body tumor.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The mention of "Lyre's sign" in the context of a mass at the carotid bifurcation is pathognomonic for a specific vascular tumor.
Step 2: Detailed Explanation:

Carotid Body Tumor (CBT): Also known as a chemodectoma or paraganglioma. It is a highly vascular tumor arising from the glomus cells of the carotid body.

Anatomy: It is located at the bifurcation of the Common Carotid Artery (CCA) into the Internal (ICA) and External (ECA) branches.

Lyre's Sign: This is a radiological sign seen on angiography or CT angiography. The tumor grows at the bifurcation and pushes the ICA and ECA apart, resembling the shape of a lyre (a musical instrument).

Clinical Signs: The mass is characteristically mobile horizontally but immobile vertically (Fontaine's sign) because it is tethered to the carotid vessels. A bruit or pulsation may be palpable.

Shamblin Classification: This is used to grade CBTs based on their degree of encasement of the carotid vessels, which helps in surgical planning.

Step 3: Final Answer:
The presence of a mass at the carotid bifurcation with the characteristic 'Lyre's sign' is diagnostic of a Carotid Body Tumor.