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Ophthalmology > CORNEA
Dermoid, Limbal
Article Last Updated: Aug 2, 2007
AUTHOR AND EDITOR INFORMATION
Section 1 of 10  
Author: Mark D Sherman, MD, Assistant Clinical Professor of Ophthalmology, Loma Linda University School of Medicine; Private Practice, Central Coast Eye Associates
Mark D Sherman is a member of the following medical societies: American Academy of Ophthalmology, American Society of Cataract and Refractive Surgery, and American Uveitis Society
Editors: Andrew W. Lawton, MD, Medical Director of Neuro-Ophthalmology Service, Section of Ophthalmology, Baptist Eye Center, Baptist Health Medical Center; Simon K Law, MD, PharmD, Assistant Professor of Ophthalmology, Jules Stein Eye Institute; Chief of Section of Ophthalmology Surgical Services, Department of Veterans Affairs Healthcare Center, West Los Angeles; J James Rowsey, MD, Director of Corneal Services, St Luke's Cataract and Laser Institute, Florida; Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri; Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Author and Editor Disclosure
Synonyms and related keywords:
dermoid, dermoid choristoma, dermoid cyst, epibulbar dermoid, epibulbar choristoma, corneal dermoid
Background
Limbal dermoids are benign congenital tumors that contain choristomatous tissue (tissue not found normally at that site). They appear most frequently at the inferior temporal quadrant of the corneal limbus. However, they may occasionally present entirely within the cornea or may be confined to the conjunctiva. They may contain a variety of histologically aberrant tissues, including epidermal appendages, connective tissue, skin, fat, sweat gland, lacrimal gland, muscle, teeth, cartilage, bone, vascular structures, and neurologic tissue, including the brain. Malignant degeneration is extremely rare. The most common system for classifying dermoids is based on the location of the lesion and separates the lesions into 3 broad categories. The most common dermoid is the limbal dermoid, in which the tumor straddles the limbus. Limbal dermoids are usually superficial lesions but may involve deeper ocular structures. The second type involves only the superficial cornea, sparing the limbus, the Descemet membrane, and the endothelium. The third type of dermoid involves the entire anterior segment, replacing the cornea with a dermolipoma that may involve the iris, the ciliary body, and the lens.
Pathophysiology
Several theories have been proposed to explain the development of limbal dermoids. One theory suggests an early developmental error resulting in metaplastic transformation of the mesoblast between the rim of the optic nerve and the surface ectoderm. Another proposed mechanism is sequestration of the pluripotential cells during embryonic development of the surrounding ocular structures. The exact pathogenesis probably varies from case to case. Limbal dermoids generally are not inherited, although some exceptions have been reported. Familial presentation of limbal dermoids in association with systemic disorders, such as Goldenhar syndrome, is well recognized and follows a multifactorial pattern of inheritance. Two rare forms of epibulbar dermoid (ie, the annular limbal form, the corneal dystrophy form) presenting in multiple family members have been reported.
Frequency
International
The estimated worldwide incidence of limbal dermoids ranges from 1 per 10,000 to 3 per 10,000.
In a study at the Armed Forces Institute of Pathology, 7.5% of epibulbar lesions examined were choristomas. According to this study, 52% of epibulbar choristomas were located in the bulbar conjunctiva, 29% at the limbus, 6% on the cornea, 4% at the caruncle, and 2.5% in the conjunctival fornix or the palpebral conjunctiva.
In a study of epibulbar choristomas in patients with Goldenhar syndrome, 14% were nasal, 86% were temporal, 16% were superior, and 84% were inferior.
Mortality/Morbidity
- Visual morbidity may result from encroachment of the lesion into the visual axis, development of astigmatism, or formation of a lipid infiltration of the cornea, which obstructs the visual axis.
- Large limbal dermoids can be cosmetically disfiguring.
- Staphyloma formation adjacent to dermoids has been reported and may be associated with spontaneous perforation of the cornea or the sclera.
Race
No racial predisposition exists.
Sex
Limbal dermoids occur with equal frequency in males and in females.
Age
- Limbal dermoids are present at birth but may not be recognized until the first or second decade of life. They may also appear to enlarge as the body matures.
- In a study conducted at the Armed Forces Institute of Pathology, 36% of epibulbar lesions removed in the first decade of life were choristomas. They constituted about 23% of epibulbar lesions removed in the second decade of life, 7.2% of lesions removed in the third decade, and 0.9% of lesions removed in the fourth decade.
- In another study conducted at the Wilmer Ophthalmologic Institute, epibulbar choristomas constituted 33% of epibulbar lesions removed before age 16 years and 2.2% of epibulbar lesions removed after age 16 years.
History
- Patients present with decreased vision or poor vision, foreign body sensation, cosmetic disfigurement, or an enlarging ocular mass.
- Most patients present before age 16 years.
Physical
- Most epibulbar dermoids are located at the inferior temporal limbus.
- Rarely, they may only affect the cornea or the bulbar conjunctiva.
- Epibulbar dermoids have a dome shape, and the surface may appear keratinized.
- Hair follicles and cilia may be visible.
- The dermoid appears fleshy and may have fine superficial vascularization.
- Associated ocular abnormalities include colobomata of the eyelids, Duane retraction syndrome and other ocular motility disorders, lacrimal anomalies, scleral and corneal staphylomata, aniridia, and microphthalmia.
- Associated systemic abnormalities include preauricular appendages and auricular fistulae (in combination with limbal dermoids constituting Goldenhar syndrome). Other abnormalities include hemifacial microsomia, microtia, and vertebral anomalies.
Causes
- Most cases of limbal dermoids are sporadic and not related to any known toxic exposure or mechanical irritant.
- Instances are reported of epibulbar dermoids being related to maternal ingestion of teratogenic agents during the first trimester of development.
Juvenile Xanthogranuloma
Peters Anomaly
Other Problems to be Considered
Foreign body granuloma
Sclerocornea
Staphyloma
Corneal scar (from trauma or infection)
Hemangioma
Atypical pterygium
An estimated 30% of patients with dermoid choristomas have associated systemic abnormalities, including Goldenhar syndrome, nevus flammeus, and neurofibromatosis.
Other systemic disorders reported include cardiovascular abnormalities, vertebral anomalies, and auricular defects.
Lab Studies
- The diagnosis of a limbal dermoid requires a directed clinical examination. Specific laboratory studies are generally not necessary.
Imaging Studies
- MRI
- Some dermoids may appear to extend into the conjunctival fornix or lateral canthus. These lesions may contain connective tissue that entangles with the orbital fat and muscle tissue belonging to the extraocular muscles.
- Radiologic imaging with an MRI can be useful in identifying such lesions, especially if surgical management is being considered.
Procedures
- Biopsy is not necessary, except in rare instances when the diagnosis is doubtful.
Histologic Findings
Limbal dermoids contain choristomatous tissue, including epidermal appendages, adipose and lachrymal gland tissue, smooth and striated muscle, cartilage, brain, teeth, and bone. Lymphoid nodules and vascular elements also have been reported. The surface of the dermoids consists of corneal or conjunctival epithelium. The lesion may be cystic or solid.
Surgical Care
- Treatment of limbal dermoids may consist of periodic removal of irritating cilia, topical lubrication to prevent foreign body sensation, or excision of the lesion if it is causing significant cosmetic disfigurement or interfering with vision.
- Surgical treatment should be instituted only when the risk of subsequent scar formation or surgical complications are outweighed by the likelihood of improving the patient's vision or cosmetic appearance.
- A superficial sclerokeratectomy, cutting flush with the surface of the globe, is the procedure of choice for removal of the dermoid. Excised tissue always should be sent to the pathologist for examination.
- Attempts at complete removal are unnecessary. The lesion may extend into the deeper structures of the eye and the risk of perforation increases if attempts are made to remove the lesion completely.
- The exposed sclera should be covered by relaxing the adjacent conjunctiva and sewing it into the scleral defect. If a deep excision is necessary, then a lamellar keratoplasty can be performed to reinforce the site of excision.
Consultations
- Obtaining a thorough family and medical history helps determine whether further consultation is necessary.
- In some cases, referral to a pediatrician with specialization in genetics is appropriate.
Prognosis
- Prognosis is generally favorable.
Medical/Legal Pitfalls
- A young patient presenting with a limbal dermoid may be at a risk of developing amblyopia. Likewise, a patient presenting with a limbal dermoid may have already developed amblyopia. This issue must be discussed with the patient and/or the patient's family. A plan for treating the amblyopia and an explanation for the possible reduction in vision should be given to the family and documented in the medical record.
| Media file 1:
Limbal dermoid in the left eye of a 13-year-old male patient. |
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| Media file 2:
Histopathological section demonstrating a pilosebaceous unit. |
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Media type: Photo
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- Baum JL, Feingold M. Ocular aspects of Goldenhar's syndrome. Am J Ophthalmol. Feb 1973;75(2):250-7. [Medline].
- Duke-Elder S. System of Ophthalmology: Congenital and Developmental Anomalies. Vol 3. 1963:488-495.
- Henkind P, Marinoff G, Manas A, Friedman A. Bilateral corneal dermoids. Am J Ophthalmol. Dec 1973;76(6):972-7. [Medline].
- Mann I. Developmental Abnormalities of the Eye. 1957:357-364.
- Mansour AM, Barber JC, Reinecke RD, Wang FM. Ocular choristomas. Surv Ophthalmol. Mar-Apr 1989;33(5):339-58. [Medline].
- Yanoff M, Fine B. Ocular Pathology. 1982:316-317.
Dermoid, Limbal excerpt Article Last Updated: Aug 2, 2007
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