A rare congenital neck lump.

We describe the case and present a radiological image of a neck lump identified antenatally with ultrasound imaging. Postnatally a left-sided asymptomatic neck lump was identified in the left posterior triangle of the neck. Repeat ultrasound and CT imaging were arranged confirming a cyst adjacent to the cervical oesophagus and displacing the carotid sheath anteriorly. Complete cyst excision was achieved with no complications. Histological analysis identified a 30×22×20 mm cyst with a smooth muscle layer within the cyst wall and a lining of respiratory epithelium. These findings were consistent with a diagnosis of cervical duplication cyst (CDC). Proximity to the carotid sheath and oesophagus can make CDC excision potentially dangerous hence preoperative CT scanning was useful to establish the anatomical relations of the cyst in this case.