LIMBAL DERMOID

Signs and Symptoms

Limbal dermoids, also known as epibulbar or conjunctival dermoids, are generally seen as well-circumscribed oval mass lesions of the ocular surface. They may be unilateral or bilateral, arising from the bulbar conjunctiva and often encroaching across the limbus onto the corneal surface. A predilection for the inferotemporal limbus has been noted.1 Dermoids are firm but “fleshy” in nature and their color may range from white to gray to pinkish yellow to brown, depending upon the specific tissue within the tumor mass. Often, blood vessels and/or hair follicles may be seen within or protruding from the dermoid.

Patients are typically quite young, with the majority of lesions diagnosed before puberty.2 Dermoids are congenital in nature, but enlarge over time; hence, the lesion may not be given much regard until the individual reaches adolescence.3,4 Smaller lesions are usually asymptomatic, but larger dermoids may cause discomfort in the form of dry eye symptoms, conjunctival irritation, or incomplete lid closure (i.e., lagophthalmos).

Visual acuity may also be impacted by larger dermoids, since these lesions can contribute to the development of astigmatism or proceed to encroach onto the visual axis. Amblyopia remains a distinct possibility in such cases.4

Pathophysiology

Dermoids are a form of choristoma, a benign, congenital tumor composed of tissue cells atypical to the organ in which they are found. Limbal dermoids consist of thick collagenous tissue and may also contain elements of skin, fat, gland, muscle, nerve, blood vessels, hair or bone. Even brain tissue has been found upon histologic analysis of some dermoids.5 The surface generally consists of simple corneal or conjunctival epithelium.

Dermoids may represent an isolated finding, or may be seen in conjunction with other ocular disorders such as scleral and/or corneal staphylomas, aniridia, congenital aphakia, cataract and microphthalmia. Dermoids are also sometimes associated with systemic abnormalities, including craniofacial abnormalities (e.g., Goldenhar-Gorlin syndrome, Franceschetti syndrome), nevus flammeus and neurofibromatosis.1,6 However, most limbal dermoids represent sporadic occurrences, and are not caused by known exposure to toxins or mechanical irritants.

An anatomical grading scale for limbal dermoids was proposed by Mann over a half-century ago, and is still used today.7 Grade I dermoids are recognized as superficial lesions measuring less than 5mm, and localized to the limbus. Grade II limbal dermoids are larger lesions covering most of the cornea and extending deep into the stroma, down to the level of Descemet’s membrane without involving it. Grade III limbal dermoids, the least common of all the presenting dermoids, are large lesions covering the entire cornea and extending through the histological structures between the anterior surface of the eyeball and the pigmented epithelium of the iris.

Management

The preferred management of a limbal dermoid depends upon the extent of the lesion (i.e., Grade I, II or III) as well as the disposition of the patient. Small, asymptomatic grade I limbal dermoids can simply be left alone, since there is no likelihood of malignant transformation. Mild irritation can be managed with ocular lubricants or even a short course of topical corticosteroids (e.g., loteprednol etabonate 0.5% QID for 3-7 days), should there be recognizable signs of inflammation. Epilation of exposed hair follicles within the lesion may also help palliate the patient.

Surgical intervention is warranted in Grade I limbal dermoids when complications exist: chronic eye rubbing due to irritation and recurrent conjunctivitis; deprivational amblyopia unresponsive to management; progressive dellen, with corneal surface decompensation; growth and encroachment into the pupillary area or optical zone; unacceptable cosmesis; induction of irregular astigmatism; or inadequate lid closure.1,8,9 Surgery is universally indicated for all Grade II and III limbal dermoids.1

Generally, the surgical procedure of choice is superficial sclerokeratectomy with excisional biopsy. When deeper excisions need to be performed, lamellar keratoscleroplasty has been shown to be safe and effective.8 The successful adjunctive use of amniotic membrane and pericardial graft tissue with this surgery has also been reported.9,10

Clinical Pearls

Limbal dermoids do not appear to show any specific predilections with regard to sex or race. The appearance may vary depending upon the patient’s skin pigmentation, since melanosis oculi can certainly influence the dermoid’s coloration.

Young patients with limbal dermoids encroaching upon the visual axis are at risk for the development of deprivation or meridional amblyopia. Specific testing, including potential acuity measurement or interferometry, should be performed on those youngsters with dermoids who also demonstrate reduced visual acuity. The finding of associated amblyopia is an absolute indication for excision of the lesion, followed by a subsequent course of vision therapy.

The most notable systemic condition seen in association with limbal dermoids is Goldenhar syndrome, a craniofacial disorder that also presents with characteristic preauricular skin tags and associated hearing loss. In addition, these patients may show underdeveloped facial muscles, malformation of the mouth or ears, spinal or cervical vertebrae problems, cleft lip/palate, renal and/or cardiac disorders, and learning disabilities.11

Families of pediatric patients with limbal dermoids should be alerted to the possibility of Goldenhar syndrome, and referred for appropriate testing.

1. Pirouzian A. Management of pediatric corneal limbal dermoids. Clin Ophthalmol. 2013;7:607-14.

2. Zhu J, Cheng HB, Fan N, et al. Studies of a pedigree with limbal dermoid cyst. Int J Ophthalmol. 2012;5(5):641-3.

3. Dey R, Dey S. Images in clinical medicine. Limbal dermoid. N Engl J Med. 2011;364(6):e9.

4. Mahdavi Fard A, Pourafkari L. Images in clinical medicine. The hairy eyeball–limbal dermoid. N Engl J Med. 2013;368(1):64.

5. Emamy H, Ahmadian H. Limbal dermoid with ectopic brain tissue. Report of a case and review of the literature. Arch Ophthalmol 1977; 95(12):2201-2.

6. Bhallil S, Benatiya I, El Abdouni O, et al. Goldenhar syndrome: ocular features. Bull Soc Belge Ophtalmol. 2010;(316):17-9.

7. Mann I. The modern approach to developmental abnormalities. Aust N Z J Surg. 1950;20(2):143-50.

8. Shen YD, Chen WL, Wang IJ, et al. Full-thickness central corneal grafts in lamellar keratoscleroplasty to treat limbal dermoids. Ophthalmology. 2005;112(11):1955.

9. Lazzaro DR, Coe R. Repair of limbal dermoid with excision and placement of a circumlimbal pericardial graft. Eye Contact Lens. 2010;36(4):228-9.

10. Pirouzian A, Holz H, Merrill K, et al. Surgical management of pediatric limbal dermoids with sutureless amniotic membrane transplantation and augmentation. J Pediatr Ophthalmol Strabismus. 2012;49(2):114-9.

11. Seymenolu G, Baer E, Tansu N, Demireli P. An unusual association of Goldenhar syndrome. Int Ophthalmol. 2013;33(1):91-4.