Tx and Followup:
Generally no treatment is necessary because of danger of damage to the globe. Prognosis is generally favorable. Surgery is indicated only when risk of subsequent scar formation or surgical complications are outweighed by the possibility of improving the patient's vision or cosmetic appearance.
Patients should seek follow-up for worsening vision, treatment of foreign body sensation, cosmetic disfigurement, or an enlarging ocular mass.
Limbal dermoids are benign congenital tumors. Clinically they appear as a well circumscribed, white, rounded lesions most often at the inferotemporal limbus and may encroach the cornea. Visual morbidity may result from obstruction of the visual axis or development of astigmatism. Limbal dermoids are generally not inherited, however, they have been associated with Goldenhar syndrome. They are present at birth, but may not be appreciated until the first or second decade of life because they enlarge as the body matures. This is a case of an incidental finding of a limbal dermoid during routine imaging for a closed head injury on a one-year-old patient with a cephalohematoma.
On imaging studies some dermoids may appear to extend into the lateral canthus or conjunctival fornix. The lesions may contain aberrant tissues such as epidermal appendages, connective tissue, muscle, cartilage, bone, teeth, skin, fat, sweat gland, lacrimal gland, vascular structures and neurologic tissue that entangles into the orbital fat and muscle tissue. Lesions may appear cystic or solid and they usually have no malignant potential. The lesion found in this case was a small, well circumscribed and was located on the sclera. It was low attenuated and did enhance post contrast administration. There were no mass effects or calcifications. Surrounding structures were normal.
The prognosis for limbal dermoids is generally favorable. Except in rare instances, biopsies are not indicated. Although they are mostly diagnosed clinically, radiologic imaging with an MRI can be useful in identifying such lesions. Surgical excision should only be instituted when the risk of scar formation or surgical complications are outweighed by the likelihood of improving the patient's vision or cosmeis. The procedure of choice is superficial sclerokeratectomy. Attempts at complete excision are not necessary because the lesion may extend into deeper structures and the globe is at risk for perforation. A patient should be seen by ophthalmology if they have changes in vision, constant irritant symptoms, and enlarging ocular mass or if they desire dermoid removal for cosmetic reasons.
Although not uncommon in the realm of ophthomology, limbal dermoids are not often documented in imaging studies. The goal of this case is to recognize limbal dermoids on CT and to be aware of their clinical significance.