Orbital heterotopic glial tissue presenting as exotropia.

A 5-month-old female infant was noted to have difficulty in fixating with the left eye with accompanying progressive exo-deviation and axial proptosis. She also had optic disc hypoplasia with the double ring sign. Computed tomography showed left superomedial orbital mass without any orbital bony defect. Incisional biopsy through a medial orbitotomy allowed significant reduction in tumor burden except for the most apical portion. The affected eye resumed normal alignment and full motility. Histopathologically, the tumor was composed of glial tissue intermixed with muscle fibers. Immunohistochemically, desmin and glial fibrillary acidic protein were strongly expressed. Minimal proptosis of the left eye heralded the recurrence of the tumor 4 years later, also confirmed by magnetic resonance imaging studies. This patient embodies the rare occurrence of isolated heterotopic glial tissue in the orbit with skeletal muscle as one of its components and optic disc hypoplasia as the associated ocular anomaly. Late recurrence may occur following incomplete tumor removal.