Neck Dermoid Cyst with Rare Imaging Appearance on Ultrasound, Elastography, and Computed Tomography

Abstract

Dermoid cyst is a type of inclusion cyst and a benign cystic teratoma containing two or more germ cell layers. It can show variable appearance on ultrasound and Computed Tomography (CT) as it is derived from squamous cell epithelium (ectoderm) and contains dermal-derived elements such as skin appendages, hair follicles, sebaceous and sweat glands. It is uncommon for a dermoid cyst to occur in the neck region during old age. The present case report highlights a rare imaging appearance of a dermoid cyst, presenting in a 65-year-old elderly male as a midline neck swelling, displaying a rare “coin in sack” appearance on ultrasound, “sack of marbles sign” on Contrast-Enhanced CT (CECT). On strain elastography, it showed characteristics of a hard mass. Diagnosing this type of large dermoid cyst with its radiological appearance is challenging. Multimodality imaging is often needed for early intervention, to prevent its rupture and transformation into malignancy. The dermoid cyst was surgically excised, and the patient was symptomatically normal on follow-up.