Treatment of Complex Choristoma by Excision and Amniotic Membrane Transplantation

Epibulbar dermoids are choristomas that generally arise from the limbus and are present at birth.¹ Based on their configuration and the histologic contents of the lesion, they are classified as dermoids, lipodermoids, or complex choristomas.^1,2 They could be either sporadic or associated with systemic anomalies like Goldenhar syndrome, neurocutaneous syndromes, or phakomatosis.³ Though they have almost no independent growth potential, the large lesions can protrude through the lid aperture causing mechanical obstruction to lid closure and can be associated with a high degree of corneal astigmatism, posing a potential threat of amblyopia in infants.^1-4 We report 2 rare cases of isolated complex choristomas that were treated successfully by excision and amniotic membrane transplantation.

A 3-month-old girl had a history of a white spot in the left eye that was noticed by her parents on the second day after birth. The child was delivered after a full-term pregnancy with a cesarean delivery. No other remarkable ocular or systemic medical history was elicited. Formal visual acuity measurement was not possible; however, the child could fix and follow a source of light. The fixation was steady, central, and maintained. Ocular motility was full. On external examination there was a soft, vascularized mass involving the left temporal bulbar conjunctiva extending to the temporal half of cornea and encroaching on the pupil. Findings on the left eye were otherwise unremarkable. Examination findings of the right eye were normal. A diagnosis of dermolipoma was made, and excision of the mass was advised in view of the risk of amblyopia. The parents deferred surgery at that time but 3 months later, they brought the child back with the complaint that the mass had increased. The mass was larger in size, soft, vascular, and involved two thirds of cornea, obscuring the pupillary area (Figure 1A). The child had a strong fixation preference with the right eye and poor fixation with the left eye. The central fundus was normal in the right eye while fundus examination of the left eye was not possible.

The lesion was excised in toto under general anesthesia. After excision of the mass, a conjunctival-limbal graft (CLAG) was harvested from the nasal and upper nasal area and was sutured on top of the amniotic graft between the 2- and 4-o'clock positions. The limbal side of the graft was sutured at the limbus with 10-0 monofilament interrupted sutures. The peripheral edge of the graft was anchored to the conjunctiva with 8-0 interrupted Vicryl sutures. A bandage contact lens was inserted after surgery. Postoperatively, steroid and antibiotic drops were administered and all sutures were removed after 1 month, at which time the ocular surface had healed and the amniotic membrane had disintegrated. Seven months postoperatively, there was scar formation with no evidence of recurrence (Figure 1B). The child was fixing light poorly with the left eye and is now receiving amblyopia therapy.

A 3-year-old girl was seen with a history of a white spot in the black of the right eye since birth. She was a healthy, full-term child from a consanguineous marriage. Her visual acuity could not be evaluated. Refraction revealed an error of +4 diopter (D)/+3 D cylinder in the right eye and +0.5 D cylinder in the left eye. There was a right convergent squint; ocular movements were full in both eyes. Anterior segment evaluation of the right eye revealed a whitish mass with patches of keratinization covering the temporal half of the cornea and extending to the lateral fornix and superiorly to the superior and medial fornix. With a probable diagnosis of lipodermoid, excision with lamellar keratoplasty was planned.

Under general anesthesia, the mass was excised piecemeal, and the corneal surface was smoothened with a No. 15 surgical blade on a Bard Parker knife(Khosla Eye Instruments, Mumbai, India), cauterizing the prominent blood vessels. The surface was covered with 2 layers of preserved human amniotic membrane with stromal side down, which was sutured to the temporal limbus and to the corneal surface nasally with circumferential 10-0 monofilament nylon sutures. Postoperatively, steroid and antibiotic drops were administered for 1 week and the loose sutures were removed 2 weeks later under general anesthesia. Three weeks after surgery, the amniotic membrane was in place and had covered the cornea well. On last follow-up, about 8 weeks after surgery, the eye was quiet and there was corneal scarring involving the temporal cornea. The child was advised to follow-up at the pediatric ophthalmology clinic for amblyopia treatment.

Both lesions showed similar features and were covered by stratified squamous as well as columnar epithelium-containing goblet cells. The underlying stroma contained lacrimal gland elements, lobules of adipose tissue, cartilage, nerve bundles, and bundles of smooth muscle (Figure 2). In the second case, there were lymphoid follicles with germinal centers in the subepithelial stroma with mild diffuse lymphoplasmacytic infiltrates in the surrounding stroma.

Dermoids are fairly common limbal lesions that are classified as choristomas because they contain displaced epithelial and dermis-like elements normally not found in these areas.³ There are 3 types of dermoids recognized: (1) the solid, well-defined limbal dermoid; (2) the more diffuse dermolipoma; or (3) the complex choristomas that contain more than 2 elements of ectopic tissues (lacrimal gland tissue, nerve bundles, cartilage, bone, etc). It is believed that epibulbar choristomas share a common origin from ectopic pluripotential cells capable of developing into either a complex growth composed of several elements or lesions containing a predominance of a single tissue.¹ The complex choristoma can be isolated or associated with linear nevus sebaceous syndrome.⁴ We report 2 rare cases of isolated complex choristoma that were treated with amniotic membrane grafting, supplemented with CLAG in 1 case. Thorough examination of both cases failed to reveal any associated ocular or neurologic abnormalities.

Treatment of dermoid depends on the size, location, and the mechanical effects of the lesion on the surrounding structures. Most dermoids are 2 to 3 mm, but they may sometimes be large (12-15 mm), causing mechanical obstruction or corneal astigmatism. Many of the reported cases were treated by excision, though some were treated with a combination of lamellar or penetrating keratoplasty^2,4; however, the results of both of these procedures are not encouraging and have led to failed grafts.

The general principles of treatment of limbal-based ocular surface lesions include wide excision of the lesion over cornea, conjunctiva, and sclera, followed by alcohol epitheliectomy, wide resection cryotherapy, or closure.⁵ Amniotic membrane has also been used as an adjunct procedure in treating diffuse ocular surface neoplasias for surface reconstruction after excision of the lesion.⁶ Keeping in mind the large size of the lesion and the age of the patient, these 2 cases were treated with excision and amniotic membrane transplantation. In case 1, CLAG was used to prevent limbal stem cell deficiency. In case 2, two layers of amniotic membrane were used for better results (as proven in the treatment of deep corneal and scleral ulcers) with the intention of providing collagen layer supplementation, basement membrane reconstruction, promotion of epithelialization, and wound healing.⁷ In both cases, visual potential was hampered by the development of amblyopia; therefore, the patients were advised to undergo antiamblyopia therapy.

Based on our experience with these 2 cases, we believe that surgical excision of large dermoids followed by amniotic membrane transplantation, with or without conjunctival-limbal autograft, is an alternative modality to achieve good ocular surface construction. With timely intervention, amblyopia may be prevented or treated early. The histologic confirmation of an unsuspected complex choristoma warrants a multidisciplinary approach.

This work was funded by the Hyderabad Eye Research Foundation.

We thank the Ramayamma Eye Bank, L. V. Prasad Eye Institute, Hyderabad, India, for providing us the preserved human amniotic membrane.

Corresponding author and reprints: Geeta K. Vemuganti, MD, Ophthalmic Pathology Service, L.V. Prasad Eye Institute, L.V. Prasad Marg, Banjara Hills, Hyderabad 500 034, India (e-mail: geeta@lvpeye.stph.net).