Dermoid and epidermoid cysts are examples of choristomas, tumors that originate from aberrant ectodermal tissue. These tumors contain normal-appearing tissue in an abnormal location. As two suture lines of the skull close during embryonic development, dermal or epidermal elements may be pinched off and form cysts. These cysts occur adjacent to a suture line (this is shown in the image below). Approximately 50% of dermoids that involve the head are found in or adjacent to the orbit, either medial or lateral.
View Image
Temporal-zygomatic suture line on the lateral orbital wall. The location of the periosteal attachment of most orbital dermoids.
Orbital dermoid cysts may displace structures in the orbit, causing proptosis, motility abnormalities, or optic nerve compression. Significant displacement may interfere with vision via compression of the optic nerve, causing optic neuropathy, or pressing on extraocular muscles, causing a motility defect, resulting in diplopia. Rupture of the dermoid, either spontaneously or with a trauma, may lead to an intense inflammatory reaction that could mimic orbital cellulitis.
At an ocular oncology center, dermoid tumors were found to comprise 2% of the orbital tumors that came to surgery.[1] Shields et al reported that dermoid cysts comprised of 24% of 645 consecutive orbital biopsies among all age groups and 46% of 250 consecutive biopsies in patients younger than 18 years.[2, 3]
Mortality/Morbidity
Morbidity is usually of a cosmetic nature; occasionally, loss of vision, diplopia, or orbital inflammation may occur. Orbital dermoid cysts almost never cause mortality.
Race
Dermoid tumors show no racial predilection.
Sex
Dermoid tumors have an equal incidence in males and females.
Age
These tumors are most often noted in young children; however, they may appear or grow at any age.
The prognosis of dermoid tumor is excellent with surgical resection. Care must be taken to evaluate the extent of the dermoid (ie, if is it a dumbbell shape around the suture line) in order to avoid cyst rupture, which could lead to a robust inflammatory response.
Patients should understand that these tumors are benign.
Tell patients that surgery generally is successful, but that serious complications can be associated with any orbitotomy (eg, ptosis, diplopia, blindness, death).
Patients generally complain of a mass, which is visible in the orbital area. Growth of these lesions is generally slow. Occasionally, a history of inflammation will be present.
Patients with deep orbital dermoids may present with marked proptosis and downward displacement of the eye.
In adults, dermoids may become symptomatic for the first time and grow considerably over a year. Based on this fact, some conclude that these lesions may be dormant for many years or have intermittent growth.
The most common location is in the superior temporal aspect of the orbit. The second most common location is in the superior nasal aspect of the orbit.
Lesions located superotemporally are generally smooth, firm subcutaneous masses attached to the orbital rim in the region of the zygomaticofrontal suture.
The mass is generally less than 1 cm in diameter, nontender, and oval in shape.
Little displacement of the globe usually occurs.
Orbital dermoid cysts are not attached to the skin, which helps differentiate them from sebaceous cysts. The cyst usually is tethered to the periosteum of the bone near suture lines, including the sinuses or intracranial cavity.[4]
Adults
The cysts are palpated less easily and have more vague borders. They are more likely to displace the globe and may erode their way into adjacent structures.
Inflammation
If the cyst ruptures, either spontaneously or with trauma, an inflammatory response may be seen. This response may be limited to injection of the conjunctiva or may be severe and mimic orbital cellulitis. Occasionally, subconjunctival droplets of fat are seen.[5]
Neurologic findings
Rarely, the cyst may press on the optic nerve and produce symptoms of optic nerve compression; reduced visual acuity, color vision and brightness perception, and a relative afferent pupillary defect.
More rarely, the cyst may induce diplopia by physically restricting movement of the globe or by compressing cranial nerves III, IV, or VI.
The dermoid cyst may displace the globe, depending on the location of the cyst.
Orbital dermoid cysts may cause neurologic complications if they compress the optic nerve or cranial nerves III, IV, or VI.
If the cyst ruptures, a marked inflammatory response follows.
Operative complications are those common to other orbitotomy procedures. Damage to the eye or adnexal structures, motility restriction, infection, inflammation, and hemorrhage may occur. Partial excision of the dermoid cyst may result in persistent inflammation, a draining sinus, or recurrence.
Radiographs often show radiolucent defects where the cyst has eroded into bone. These defects can be large with distinct margins and may show sclerotic changes.
CT or MRI studies
CT or MRI studies have largely supplanted plain radiography for evaluating dermoid cysts.
A review of 160 CT studies of orbital dermoids revealed that 65% were lateral and 30% were medial to the globe, only one was entirely behind the globe, 85% had changes in adjacent bone, 73% had a visible wall, 27% had a CT attenuation similar to orbital fat, 14% had calcification, 5% had a fluid level, and 20% had abnormal soft tissue outside the cyst.[6] The cyst lumen is generally homogeneous but can also be heterogeneous depending on the amount of lipid and keratin within it. The lumen does not enhance with contrast.[7]
On MRI, features include a cystic appearance, internal fat attenuation (T1 hyperintensity), internal calcification, and fluid levels.[8] The wall of the cyst but not the lumen may show enhancement with gadolinium. These features are uncommon in rhabdomyosarcoma. On MRI diffusion-weighted imaging, dermoids are high in signal intensity.
Ultrasonography
Ultrasound characteristics of dermoid cysts include a smooth contour and variable echogenicity.[9]
Color Doppler imaging
Color Doppler imaging of dermoid cysts shows no intralesional blood flow, which can help differentiate them from hemangioma and rhabdomyosarcoma.[9]
The external layer of the cyst has variable thickness and may be exceedingly thin. The cyst is generally connected to periorbita by fibrovascular tissue. Epidermoid cysts have a lining of epithelial cells, usually stratified, that produce keratin. Dermoid cysts contain blood vessels, fat, collagen, sebaceous glands, and hair follicles. The material in the cyst varies from a tan, oily liquid to a white or yellow substance that resembles cottage cheese or even a relatively solid mass. Often, high cholesterol content is present. The cysts commonly are inflamed and may contain free blood. See the image below.
Dermoid cysts usually are cosmetic problems. The location of the dermoid cyst in the orbit helps determine the appropriate type of orbitotomy. A method for percutaneous drainage and ablation of orbital dermoid cysts[10] and endoscopic-assisted removal of orbital dermoid cysts has been reported.[11] In 2019, Bajric and Harris reviewed locations of the dermoid and how they altered surgical approaches. The cysts were stratified into anterior, superior, medial to the frontozygomatic suture, anterior and medial across the suture, and those forming a sinus from the orbit to the skin.[12]
Inflammation from preoperative or intraoperative rupture of the cyst can be controlled with the use of prednisone.
Failure to remove the entire cyst may result in persistent inflammation, a draining sinus, or recurrence of the cyst.
Dermoid cysts generally have a good prognosis. If they are excised completely, usually only minimal scarring occurs. If they are observed rather than excised, slow growth can be expected.
Clinical Context:
The most commonly used oral corticosteroid to control inflammation. May decrease inflammation by reversing increased capillary permeability and suppressing PMN activity.
Have anti-inflammatory properties and cause profound and varied metabolic effects. Corticosteroids modify the body's immune response to diverse stimuli.
Anna G Gushchin, MD, Clinical Assistant Professor of Ophthalmology, Loyola University Medical Center; Attending Oculoplastic Surgeon, John H Stroger Hospital of Cook County
Disclosure: Nothing to disclose.
Coauthor(s)
Alexander K Nugent, MD, Resident Physician, Department of Ophthalmology, Stanford University School of Medicine, Byers Eye Institute
Disclosure: Nothing to disclose.
Talmadge (Ted) Cooper, MD, Clinical Associate Professor, Department of Ophthalmology, Stanford University School of Medicine
Disclosure: Nothing to disclose.
Tarek El-Sawy, MD, PhD, Clinical Assistant Professor, Ophthalmic Plastic and Reconstructive Surgery, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine
Disclosure: Nothing to disclose.
Specialty Editors
Simon K Law, MD, PharmD, Clinical Professor of Health Sciences, Department of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, David Geffen School of Medicine
Disclosure: Nothing to disclose.
Chief Editor
Hampton Roy, Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Shields JA, Bakewell B, Augsburger JJ, Donoso LA, Bernardino V. Space-occupying orbital masses in children. A review of 250 consecutive biopsies. Ophthalmology. 1986. 93(3):379-84.
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