【摘要】迷芽瘤是儿童最常见的眼球上损伤，通常位于眼球表面，不涉及角膜或巩膜深层。由于高度散光和瘤的存在，眼球表层皮样囊肿常常引起弱视和美观问题，唯一治疗方法是手术。以前鼓励根据皮样囊肿的位置和深度行板层角膜移植术或穿透角膜移植术，但由于移植伴有弱视和血管生成高发率，治疗结果并不理想。本文报道了1例5岁女童右眼非综合征性眼球表面迷芽瘤，该女童接受了右眼皮样瘤切除联合板层角膜移植，术后美观问题得以改进，但散光和视力未见提高，因此术后应重视弱视治疗。
【关键词】 迷芽瘤；眼球上的；板层角膜移植术；弱视
Nonsyndromic young girl with epibulbar choristomas: the never end battle
Che Mahiran Che Daud , Retnasabapathy Shamala , LizaSharmini Ahmad Tajudin
Department of Ophthalmology, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, Kubang Kerian 15160, Kelantan, Malaysia Department of Ophthalmology, Hospital Kuala Lumpur, Jalan Pahang 50586, Kuala Lumpur, Malaysia
Abstract
Choriostomas represent the most common epibulbar lesions in the pediatric age group. Generally, they are on the surface and do not involve the deeper layer of cornea or sclera. Epibulbar dermoids frequently cause amblyopia and cosmetic problems due to high astigmatism and the presence of the tumor. Surgery is the only option for epibulbar dermoids. Lamellar or penetrating keratoplasty has been advocated depending on the site and the depth of the epibulbar dermoids. However, the outcome is not always promising due to accompanying amblyopia and high incidence of vascularization of the grafts. In the present article we report a case of epibulbar choriostomas in the right eye of a 5yearold, nonsyndromic girl who underwent right limbal dermoid excision with lamellar keratoplasty. Postoperatively she was improved cosmetically, however the astigmatism and the vision remained the same. Therefore the amblyopic therapy should be emphasized postoperatively.
KEYWORDS:choriostomas;epibulbar;lamellar keratoplasty; amblyopia
INTRODUCTION
Epibulbar choristomas (limbal dermoids) are congenital benign tumors consisting of tissue from ectodermal and mesodermal origin and present as yellowish white bulbous lesions in the limbal area [1]. They can cause not only cosmetic problems but also visual impairment secondary to high astigmatism, encroachment of lipid infiltrate or lesion on the visual axis. A large or elevated mass may also cause dellen formation, irritation, and drying or superficial keratitis [1]. Surgical management is the only way to deal with limbal dermoids when the treatment is indicated, and amblyopia therapy is an important adjunct to surgical management [1]. We report a case of right eye limbal dermoid in a 5yearold nonsyndromic girl who underwent right limbal dermoid excision with lamellar keratoplasty.
CASE REPORT
A 5yearold healthy girl was brought to our department with history of limbal growth of ther right eye since birth. Her mother claimed the progressively increased growth in size. There was no history of recurrent red eye, eye discharge or painful right eye, and any history of trauma was denied. There was no history of eye deviation or abnormal head posture, either. She was a full term baby delivered via spontaneous vaginal delivery. There was no problem during her pregnancy and postnatally, and her developmental milestones were otherwise normal. There was no family history of ocular disease or similar problem in the family.
Both eyes were orthophoric on ocular examination. There was no abnormal head posture or nystagmus. There was absence of preauricular tag or auricular fistulae. Her bestcorrected visual acuity was 6/18 in the right eye and 6/7.5 in the left. There was absence of ptosis, lid mass and conjunctival mass. Right inferotemporal epibulbar mass (6 to 8 clock hours) was present measuring about 7mm×7mm (Figure 1). The mass was noninflamed with welldefined margin and the presence of hair follicle on the top. The anterior segment examination of the right eye showed the cornea was clear, with no dellen formation or punctate keratopathy. The results of anterior segment of the left eye and posterior segment examinations of both eyes, the examination of left eye and systemic examinations were normal.
Cycloplegic refraction of the right eye revealed+3.00/3.00×40 and the vision improved to 6/12. The left eye was emmetropic. The mother was advised to encourage her daughter to wear glasses and to patch the right eye for 2 hours per day as the amblyopic treatment. However, after 7 months of amblyopic treatment, she was not compliant wiith the patching therapy and the right eye vision dropped to 6/24. Subsequently the child underwent right limbal dermoid excision and lamellar keratoplasty.
Intraoperatively, right 8mm lamellar cornea graft was secured onto a 7.75mm bed with 16 interrupted, 100 nylon sutures (Figure 2). Postoperatively, she was started with topical steroid and topical chloramphenicol every 2 hours. Cornea epithelization was noted after 1 week of followup. Postoperative cycloplegic refraction of the right eye revealed +0.5/3.00×45, and the astigmatism and the vision remained the same. The amblyopic patching of the left eye was restart for 4 hours daily. The histopathology examination of the surgical specimen confirmed the diagnosis of limbal dermoid (Figure 3).
Figure 1Right inferotemporal epibulbar mass（略）
Figure 2Right 8mm lamellar cornea graft was secured onto a 7.75mm bed with 16 interrupted sutures（略）
Figure 3Histologic section shows epidermis, dermis, epidermal appendages, and adipose tissue（略）
DISCUSSION
About 10% to 29% of the pathological lesions at the limbus are caused by epibulbar choriostomas (limbal dermoids) [2]. Limbal dermoids is commonly found in the inferotemporal quadrant [1]. There is an association with a systemic syndrome in 30% of cases such as Goldenhar syndrome and epidermal nevus syndrome [1]. It can be classified under three categories by the extent of their involvement: small, straddling at limbus up to 5mm in size; large, covering entire cornea surface but not progressing beyond Descement membrane; and extensive, replacing cornea, anterior chamber and iris stroma and lined posteriorly pigment epithelium of iris [3].
The timing and the method of intervention in the management of limbal dermoids depend on the size of the lesion and its potential for causing amblyopia. Surgical management is the only option for epibulbar dermoids. The indications of surgery are, for cosmetic reasons, irritative symptoms because of the growth, hair on the growth, poor vision either due to encroachment of the cornea (by tumor or the lipid infiltration line in front of the mass) or to high astigmatism and diplopia. The type of surgery is dependent upon the size, site, depth of involvement and the nature of the growth. Surgery in children younger than 1 year was mainly due to obstruction of the visual axis by large lesion, which necessitated a large graft. The poorer acuity in those operated on for visual reasons is related to the size of the graft but might also be due to coexisting amblyopia.
Small tumors may not require surgery because sometimes the postoperatives scar and complicated pseudopterygium might produce more cosmetic blemish than the growth itself. Furthermore, a simple excision is not sufficient to manage the extensive lesion because keratectomy conducted during excision gives rise to surface irregularities, thus leading to tear fluid abnormalities, which in long run, can give rise to vascularised corneas [4]. Therefore, simple excision alone or with keratectomy is recommended in lesion less than 5mm in size with superficial involvement [1]. Lamellar keratoplasty is recommended to prevent the occurrence of pseudopterygium post excision of limbal dermoid. Scott and Tan [5] reported that lamellar keratoplasty was safe and provided good cosmetic results. In addition, lamellar keratoplasty as a primary procedure offers tectonic stability and eliminates the problems of vascularization and pseudopterygium.
High astigmatism is a major cause of poor vision in patient with limbal dermoids. Cuttone et al [6] created an animal model by suturing a sponge into the limbus to induce peripheral flattening and concluded that the astigmatism was due to external compression. Scott and Tan [5] proposed that the astigmatism is caused, at least partially, by alternation and molding of intrinsic structure of corneoscleral wall, thus cannot be corrected by surgery.
Panton and Sugar [7] demonstrated that the dermoid flattened the cornea underneath the lesion causing variable effects on the central corneal. Although the underlying mechanism was not fully understood, limbal dermoidinduced astigmatism has been widely accepted as an indication for surgery. However, some researchers found that the astigmatism was not significantly changed after the surgery [68]. In fact, it may even induce more astigmatism in some patients [9].
In addition to high astigmatism, cosmesis is another major indication for surgery. In order to create a good cosmetic result, maintaining the transparency of the cornea area, whitish color of scleral area and preventing the opacity and neovascularization of the donorrecipient interface are extremely important. Because the central graft is transparent and not able to provide the whitish color of the scleral bed, corneoscleral grafts are theoretically more appropriate in reconstructing the original structure and appearance of corneasclera junction. Apart from that, the whitish color of the scleral bed can still be seen easily through the transparent central corneal grafts, leading to a satisfactory cosmetic result. In our patient, we considered surgery mainly because of cosmesis and amblyopia induced by astigmatism. However, we explained to the parents the expectation of postoperative results, in which the vision might be similar or slightly improved.
Hence, the amblyopic therapy should be emphasized postoperatively.
In conclusion, limbal dermoid with lamellar keratoplasty in eyes with deep and large lesion still gives encouraging results from both anatomical and functional point of view. The visual prognosis is good in patients receiving surgery combined with adequate amblyopia treatment.
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