Bilateral epibulbar and posterior scleral choristomas in linear nevus sebaceous syndrome.

Abstract

Sir, Linear nevus sebaceous syndrome (LNSS) is characterized by nevus sebaceous, mental retardation, seizures and ocular abnormalities (Wilkes et al. 1981). Epibulbar choristomas are common (Mansour et al. 1986; Lambert et al. 1987), while posterior scleral choristomas are very rare. We report the clinical and histopathological findings of a patient with LNSS. A 9-month-old male with bilateral epibulbar masses and a linear scalp nevus was admitted to our outpatient clinic. Pregnancy and delivery had been normal and there was no family history of consanguinity or birth defects. Examination of the right eye showed an upper eyelid defect, a large superior epibulbar and a smaller nasal limbal mass, and optic disc tilting with a peripapillary chorioretinal atrophy. Ocular motility and the anterior segment were normal. Vision was central, steady and maintained. Examination of the left eye showed an upper eyelid defect and large superonasal epibulbar mass involving the entire cornea (Fig. 1). The posterior segment could not be visualized. A linear nevus and patchy alopecia were also observed. Bilateral complex epibulbar choristomas with upper eyelid coloboma. Histopathological examination of the excised epibulbar masses showed non-keratinizing, stratified, squamous epithelium covering a loose, connective tissue that contained adipose tissue, dilated capillaries, glandular tissue, cartilage and nerve tissue. The masses were assessed as complex choristomas. The scalp lesion showed keratinizing, stratified, squamous epithelium covering the connective tissue that contained sebaceous glands. B-scan ultrasonography revealed bilateral, highly reflective, placoid lesions at the scleral−choroidal interface, with orbital shadowing typical of calcification. Computed tomography of the orbit showed posterior pole lesions with bone density in both eyes (Fig. 2). Orbital tomography showing lesions of bone density in the posterior aspects of both globes. Epibulbar choristomas are common in LNSS and may occur bilaterally in some cases (Duncan et al. 1998). Complex choristomas are rare epibulbar tumours and are characterized by the presence of two or more ectopic tissues (Traboulsi et al. 1999). Surgical treatment may be required because of involvement of the cornea or astigmatism, and lamellar keratoplasty is the preferred technique (Mansour et al. 1986). In our case, the choristomas were bilateral and histopathologically complex, showing adipose tissue, glandular tissue, dilated capillaries, cartilage and nerve tissue. The choristomas in the right eye were removed and a peripheral lamellar keratoplasty was performed, but the choristoma in the left eye was only partly removed due its deep invasion into the ocular surface. Other ocular findings which may be present with LNSS are eyelid colobomas and masses, ptosis, nystagmus, strabismus, corneal vascularization, microphthalmia, macrophthalmia, iris coloboma, cataract, chorioretinal coloboma, staphyloma, optic disc coloboma, optic nerve glioma, pseudopapilloedema, choroidal osteoma and cortical visual impairment (Wilkes et al. 1981; Duncan et al. 1998). Our case had bilateral eyelid colobomas, limbal choristomas and posterior scleral choristomas. Posterior scleral choristomas were characteristic, and B-scan ultrasonography and CT scans showed posterior pole lesions with bone density in both eyes. No growth of these lesions has been observed to date, and follow-up examinations continue. Nevus sebaceous may be associated with malignancy (Mehregan & Pinkus 1965). Therefore, these patients must be monitored closely. In our patient, the nevus sebaceous has shown no evidence of malignant transformation. Neurological abnormalities, seizures and mental retardation, quadriparesis, microcephaly and diencephalic syndrome may be observed (van de Warrenburg et al. 1998). Our patient had seizures, hemiparesis, hypotonia, deafness, mental retardation and developmental delay and has received antiepileptic drugs for treatment of seizures. The ocular, neurological and cutaneous manifestations of patients with LNSS should alert physicians to the diagnosis.