What are dermoid cysts?

Updated: Jan 30, 2020
  • Author: Ginard I Henry, MD; Chief Editor: Gregory Gary Caputy, MD, PhD, FICS  more...
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Dermoid cysts are mobile, firm, subepidermal lesions that are often present at birth and occur most commonly on the face and scalp. The lesions are flesh colored and do not transluminate, which differentiates them from the similarly presenting encephalocele. They frequently occur along the superior lateral periorbita but can present anywhere along the lines of embryonic closure as well as along the cervical midline and mastoid area. Rarely, they can occur along the spine, penis, testes, and floor of mouth. In 50% of dermoids, a dermoid sinus (or ‘pit’) is present. They are a cutaneous defect or blind passage that is usually located centrally on the dermoid. A dermoid-appearing lesion with a central pit with protruding hairs is pathognomonic of a dermoid cyst.

A dermoid cyst is a hamartomatous tumor that is usually evident at birth and is caused by a disorder of embryonic epithelium growth at embryonic fusion sites during craniofacial development. Dermoid cysts are a result of the sequestration of skin along the lines of embryonic closure.

The cyst wall is composed of squamous epithelium with associated adnexal structures such as hair follicles and sebaceous glands. These cysts can contain structures from one or more of the 3 primary embryonic germ layers: skin, hair, and teeth.

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