Bilateral orbital glial heterotopia: A rare case report.

Glial heterotopia is a rare congenital mass that often presents as a unilateral mass lesion in or around the nose. Complete surgical excision is the treatment of choice. However, before any surgical intervention for suspected glial heterotopia, distinction should be made both clinically and radiologically from the pathologically related encephalocele to prevent the risk of cerebrospinal fluid leak and meningitis. Here, we report a rare case of bilateral orbital glial heterotopia in a 2-year-old child with review of the literature.

Introduction

Glial heterotopia is a rare congenital (often midline) developmental, nonneoplastic displacement of neuroglial tissue in extracranial sites without connection to the cranial cavity.[1] As it occurs commonly in or around the nose, it is often referred to as nasal glial heterotopia.[2] The incidence of congenital midline nasal masses is rare and reported to be 1 in 20,000–40,000 live births with nasal glial heterotopia accounting for approximately 5% of cases.[3] Most reported cases of glial heterotopias occur as a unilateral midline nasal lesion. Herein, we report an unusual case of bilateral orbital glial heterotopia successfully managed in our center.

Case Report

A 2-year-old male child was brought to our hospital with a history of swellings on both sides of the nasal bridge since birth. The swellings were said to be increasing in size gradually, but there was no associated change in size with crying. The child was born at term following an uneventful pregnancy, labor, and delivery. There was no history of swelling in other parts of the body or in the family. The developmental milestones were appropriate for the age.

Examination revealed symmetrical, ovoid swellings on both sides of the inferior medial periorbital area largely below the medial canthal angles measuring 20 mm in the widest diameter. The skin at the nasal bridge in between the masses was dimpled [Figure 1]. The swellings were soft, nonpulsatile, nontender and firmly attached to underlying structures. No other abnormality was observed. Our initial working diagnosis was dermoid cyst keeping in mind possible differentials such as dacryocystocele, encephalocele, and meningocele.

Figure 1

(a) Preoperative photograph, (b) axial and (c) coronal computed tomography images showing bilateral medial periorbital lesions extending into the anterior orbits especially on the left side

Routine hematological and biochemical tests as well as chest X-ray were normal. The computed tomography (CT) scan showed bilateral medial periorbital lesions extending into the anterior orbits, especially on the left side. There was a mild concave deformity of underlying bone on the left side. No evidence of direct communication with the brain was seen [Figure 1].

The swellings were excised completely, and histopathological examination confirmed diagnosis of glial heterotopia. Examined sections revealed fragments of fibromuscular tissue exhibiting aggregates of mature glial tissue along with scattered lymphoid follicles. No proper cyst lining or stratified squamous epithelium or appendageal structures were identified. On immunohistochemistry, glial fibrillary acidic protein (GFAP) was positive [Figure 2].

Figure 2

Immunohistochemistry showing positivity for glial fibrillary acidic protein (glial fibrillary acidic protein ×10)

Discussion

Glial heterotopias usually present at birth, and 90% of cases are diagnosed by the age of 2 years.[1] Most of the reported cases were unilateral as nasal or extranasal orbital, nasopharyngeal, middle ear, or scalp swellings.[123] Bilateral occurrence of glial heterotopia is quite uncommon, and to our knowledge, only one case involving the orbits has been reported in the literature.[4]

The exact pathogenesis of nasal glial heterotopias has not been fully established. However, the most widely held theory is that glial heterotopias represent an encephalocele that becomes sequestrated from the brain and cranial vault early in gestation. In 15%–20% of cases, a fibrous stalk that was not found in our case exists to connect the swelling to the intracranial space.[3]

Most cases of extranasal glial heterotopias in intrapulmonary and peritoneal locations remote from the neuraxis occur in association with neural tube defects and are thought to be due to shedding of neuroglial elements into the amniotic fluid with subsequent implantation into tissues developing in direct contact with them.[5] Interestingly, Siddon and Hui through DNA genotyping have proven the hypothesis that glial tissue involving the uterine cervix and endometrium arose from implanted fetal tissue during evacuation of conception (abortion).[6]

Although glial heterotopias are benign lesions, they can cause a number of clinical problems depending on their location. Intranasal lesions may present with nasal obstruction, epistaxis, or nasal deformity.[1] Extranasal glial heterotopias on the face are more often associated with cosmetic disfigurement like in our case. Orbital glial heterotopias can cause mass effect in the orbit with associated globe displacement, proptosis, exotropia, and varying degrees of vision-related problems.[27] None of these mass effects were observed in our case because of relative anterior position of the heterotopic tissue. The medial canthal location of the lesion in our patient could have caused lacrimal sac and/or canalicular compression and obstruction with resultant epiphora. Perhaps, some of these mass effects would have occurred later if not excised because of continued growth of the lesion.

The uncommon bilateral nature of the mass in our patient tends to lend support to possibility of bilateral dacryocystocele on initial look. Glial heterotopia needs to be differentiated from encephalocele to which it is pathologically related because of the risk of cerebrospinal fluid leak and meningitis associated with the later.[8]

Histologically, the glial tissue can be confirmed by immunoreactivity for GFAP or S100 protein. Neurons are rare or absent.[1]

The preferred treatment is complete surgical excision. Early surgical intervention is advocated as there is a chance of distortion and erosion of the facial bone due to the growth of glial heterotopias.[8] Preoperative evaluation by CT and magnetic resonance imaging helps in determining the exact extent and location of the mass and to rule out any contiguity with the central nervous system. Biopsy or fine-needle aspiration is contraindicated unless an intracranial connection is ruled out by imaging studies.

Conclusion

Glial heterotopia should be considered in cases of unilateral or bilateral congenital medial periorbital/orbital masses. Before any form of surgical intervention for suspected glial heterotopia, distinction should be made both clinically and radiologically between it and encephalocele to prevent the risk of cerebrospinal fluid leak and meningitis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.