Glial Heterotopia of the orbit: A rare presentation
Glial heterotopias are rare, benign, congenital, midline, non-teratomatous extracranial glial tissue. They may masquerade as encephalocoele or dermoid cyst and mostly present in nose. Herein, we present an unusual case of glial heterotopia of the orbit with unilateral blindness.
A 6 year-old-boy presented with a progressive painless mass over the nose and medial aspect of the left eye noticed since birth. On examination, the globe was displaced laterally by a firm, regular, mobile, non-pulsatile and non-tender medial mass. The affected eye had profound loss of vision. Computed tomography scan showed a large hypodense mass in the extraconal space with no intracranial connectivity and bony erosion. The child underwent total surgical excision of the mass and histopathological examination confirmed glial heterotopia of the orbit.
Though the incidence of this condition is rare, the need of appropriate diagnosis and management of such mass to prevent the visual and cosmetic deterioration is warranted. To our knowledge this is the first reported case of Glial heterotopia of orbit causing unilateral blindness.
KeywordsAstigmatism Dermoid Cyst Horizontal Meridian Glial Tissue Medial Orbital Wall
Glial heterotopia also known as Nasal glioma represents collections of normal glial tissue in an abnormal location distant to the central nervous system with no intracranial connectivity . The most common reported site of heterotopic neuroglial tissue is in and around the nose . Sixty percent of gliomas are extranasal, 30% are intranasal, and 10% are both . Although benign, they can cause significant local damage and cosmetic deformity by compressing and destroying the nasal cartilage and orbital wall. Gliomas form an uncompressible mass that does not increase in size on the valsalva testing and does not transilluminate. Unlike dermoids, they do not necessarily occur in the midline, or attach to sinuses or skin. Confirmatory diagnosis of Glial heterotopia can be done with the help of imaging and histopathological findings supported by immunohistochemical presence of glial fibrillary acidic protein and S100 protein . Surgical excision is the mainstay of treatment for Nasal gliomas, but they must be differentiated from encephalocele and other midline nasal masses before the surgery is scheduled.
This case emphasizes on the appropriate diagnosis of the midline nasal masses and the importance of early diagnosis and treatment for the better visual and cosmetic prognosis. Earlier the diagnosis better is the treatment and the probability of visual recovery is more. They are generally present at birth, or become manifest within the first few years of life, but can be seen in any age group. In our patient, though the mass was present since birth, the presentation was late due to illiteracy and financial barriers of the family.
Nasal gliomas may masquerade as encephalocoeles or dermoid cysts due to similar embryological origin. The nasal glioma, however, is ectopic sequestrated tissue and not a herniated structure and careful examination is required to rule out their intracranial connection so that it may not lead to catastrophic CSF leaks during surgery.
To the best of our knowledge, the effect in visual and refractive status of the eye caused by these masses has been rarely addressed in previous reports. It is interesting to note that there was presence of -12.00D of against the rule astigmatism in our case. This signifies that the mass had been pressing the globe horizontally leading to the steeper horizontal meridian. The child was unilaterally blind most probably due to meridional amblyopia as suggested by the keratometry and refractive findings. Hence, the amblyogenic effect of the mass on the globe should also be considered while evaluating these types of cases.
Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor in-Chief of this journal.
We would like to acknowledge pathologists from Department of Pathology, Tribhuvan University Teaching Hospital, for the histopathology report of the sample and Mr. Suresh Raj Sharma for his photography.
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