Dermoid cysts on the
face, neck, or scalp are subcutaneous cysts that are usually
present at birth. Intracranial or perispinal dermoid cysts are
most often found in infants, children, or young adolescents.
In contrast to epidermal cysts, dermoid cysts
in the skin are lined by an epidermis that possesses various
epidermal appendages. As a rule, these appendages are fully
mature. Hair follicles containing hairs that project into the
lumen of the cyst are often present. The dermis of dermoid cysts
usually contains sebaceous glands; eccrine glands; and, in many
patients, apocrine glands. Occasionally, the lining epithelium
may proliferate as papillary boundaries extend externally or
inward toward the lumen of the cyst. This proliferation may have
some superficial resemblance to epidermal carcinomatous
proliferation, and the growth may be misclassified as a cancer.