Dermoids
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Etiology
Dermoid cysts are benign tumors that result from misplaced or trapped skin and other tissues during embryonic development. Roughly 25% of dermoid cysts are found at birth but can also be diagnosed in adults in the deep orbital tissues. Most commonly, they are found on the lateral aspect of the upper eyelid.
Differential Diagnosis
There are some conditions that show similar symptoms, including encephalocele, lacrimal mass or lacrimal tumor.
Work-up / Course / Prognosis
CT/MRI images show round to oval shaped cystic lesion with a defined border.
Symptoms
Symptoms include a slow-growing smooth mass, usually painless, around the eye orbit. Deeper dermoid cysts can grow larger and cause ptosis, proptosis, diplopia, strabismus or restriction of extraocular movements. A cyst rupture can cause inflammation, redness, edema, and pain.
Signs
Aside from the listed symptoms, dermoid cysts typically do not displace the globe and do not raise intraocular pressure.
Locations
Periorbital dermoid cysts develop near the outside edge of the eyebrow whereas epibulbar dermoid cysts occurs on the surface of the eye. Intraconal dermoid cysts are on the inside of the eye muscles, corneal dermoid cysts are on the cornea, and orbital floor dermoid cysts are on the lower eyelid and can cause proptosis.
Pathology
Dermoid cysts are a benign cutaneous developmental anomaly that arise from the entrapment of ectodermal elements along the lines of embryonic closure.
Lining
The lining of dermoid cysts is comprised of keratinizing, stratified squamous epithelium or nonkeratinized stratified squamous epithelium.
Filling
Inside the dermoid cysts is keratin. This is a greasy, yellowish material that contains skin cells, hair, fat and gland material.
Treatment
Due to their potential for growth, dermoid cysts are usually surgically removed.
