Diagnosis: Midline cervical epidermoid cyst
Derived from ectodermal tissue trapped during embryonic fusion, epidermoid cysts are a variant of a dermoid cyst, lined with simple squamous epithelium with a fibrous wall and no adnexal structures.1 In the pediatric population, dermoid cysts and their variants account for up to 26% of congenital neck masses.2,3 When they arise in the midline neck, they are often difficult to differentiate from a thyroglossal duct cyst (TGDC) by physical examination alone.2,3 Both epidermoid cysts and TGDCs often appear as enlarging, soft, painless masses that are unattached to the overlying skin.4 While many TGDCs move with tongue protrusion, most epidermoid cysts do not.5 However, detecting movement of TGDCs during deglutition and tongue protrusion is often difficult to assess in children. In addition to epidermoid cysts and TGDCs, the differential diagnosis of midline cystic masses should also include thymic cysts, plunging ranulas, true dermoid cysts, teratomas, branchial cleft cysts, and lymphadenitis.
Pathology Quiz Case 1: Diagnosis. Arch Otolaryngol Head Neck Surg. 2011;137(9):962-963. doi:10.1001/archoto.2011.142-b