Handbook of Ocular Disease Management

LIMBAL DERMOID

Signs and Symptoms

Pigmented dermoid.

Limbal dermoids, also known as epibulbar or conjunctival dermoids, are generally seen as well-circumscribed oval mass lesions of the ocular surface. They arise from the bulbar conjunctiva and virtually always protrude across the limbus onto the cornea. A predilection for the inferotemporal limbus has been noted. 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 on average quite young, with the majority of lesions diagnosed before puberty. Dermoids are congenital in nature, but enlarge over time; hence, the lesion may not be given much regard until the individual reaches adolescence. Smaller lesions are typically asymptomatic, but larger dermoids may cause discomfort in the form of dry eye symptoms, conjunctival irritation or lagophthalmos. Visual acuity may also be impacted by larger dermoids, since these lesions may contribute to the development of astigmatism or encroach onto the visual axis.

Pathophysiology

Dermoids are a form of choristoma--that is, they are benign, congenital tumors 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.¹ 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 or oculosystemic disorders, including eyelid and iris colobomas, microphthalmos, and retinal or choroidal defects. Fully 30% of dermoids are associated with systemic abnormalities, including craniofacial abnormalities (e.g., Goldenhar syndrome), nevus flammeus and neurofibromatosis. However, most limbal dermoids represent sporadic occurrences, and are not caused by known exposure to toxins or mechanical irritants.

Management

The preferred management of a limbal dermoid depends upon the extent of the lesion and the disposition of the patient. Small, asymptomatic lesions 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., prednisolone sodium phosphate 1%, Lotemax, or Alrex [Bausch & Lomb], q2h-qid x 3-7 days). Epilation of exposed hair follicles may also help palliate the patient. When definitive treatment is indicated--as in the case of profound cosmetic concern, physical irritation or visual impairment--surgical excision is the preferred technique. Surgery must be performed with caution however, since these lesions are occasionally contiguous with tissue of the sclera and orbit.

Generally, the surgical procedure of choice is superficial sclerokeratectomy with excisional biopsy. When deeper excisions need to be performed, lamellar keratoplasty has been shown to be safe and effective.^2-4 Preopera-tive evaluation with ultrasound biomicroscopy may well improve the visualization of the lesion, hence enhancing surgical planning and the potential outcome.^5,6

Clinical Pearls

Limbal dermoids show no specific predilections with regard to sex or race. The appearance may vary depending upon the patient's skin pigmentation; melanosis oculi can influence dermoid coloration.
The most notable systemic condition associated 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 or cardiac disorders, and learning disabilities. Families of pediatric patients with limbal dermoids should be alerted to the possibility of Goldenhar syndrome, and referred for appropriate testing.
Young patients with limbal dermoids that encroach the visual axis are at risk for developing deprivation or meridional amblyopia. Specific testing, including potential acuity measurement or interferometry, should be performed on those youngsters with dermoids and 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.

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.
Mader TH, Stulting D. Technique for the removal of limbal dermoids. Cornea 1998; 17(1):66-7.
Scott JA, Tan DT. Therapeutic lamellar kerat oplasty for limbal dermoids. Ophthalmology 2001; 108(10):1858-67.
Panda A, Ghose S, Khokhar S, et al. Surgical outcomes of epibulbar dermoids. J Pediatr Ophthalmol Strabismus 2002; 39(1):20-5.
Hoops JP, Ludwig K, Boergen KP, et al. Preoperative evaluation of limbal dermoids using high-resolution biomicroscopy. Graefes Arch Clin Exp Ophthalmol 2001; 239(6):459-61.
Grant CA, Azar D. Ultrasound biomicroscopy in the diagnosis and management of limbal dermoid. Am J Ophthalmol 1999; 128(3):365-7.

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