Case 3

This is a CT neck study showing a well defined lesion in the neck, immediately below the angle of the mandible, between the right sternocleidomastoid muscle and carotid space. The lesion is rounded and cystic with low attenuation (simple fluid) contents, and has thin yet enhancing walls. It contains internal enhancing septations.

There are no enlarged adjacent lymph nodes.

The most likely diagnosis is a 2^nd branchial cleft cyst. The presence of septations and wall enhancement suggests infection. The differential diagnosis includes a suppurative lymph node / necrotic lymph node / cystic nerve sheath tumour.

I would suggest discussion of this case at the relevant MDT. Surgical excision would be the likely management.