Optic Glioma Gone Astray

Introduction:Malignant optic gliomas occur almost exclusively in adults but aggressive behavior has been reported by Bilgin et al in tumors that are histologically low grade (WHO I/II). Although it may occur with or without prior radiation therapy, intratumoral hemorrhage is rare.

Poster 147 Optic Glioma Gone Astray John Carter1, Homer Chiang1, Andrea Gilbert1, Carlos Bazan1 1 UT Health San Antonio, San Antonio, USA Introduction: Malignant optic gliomas occur almost exclusively in adults but aggressive behavior has been reported by Bilgin et al in tumors that are histologically low grade (WHO I/II). Although it may occur with or without prior radiation therapy, intratumoral hemorrhage is rare. Description of Case(s): A 46 year old male was referred for decreased peripheral vision in the left eye. Exam showed a left afferent pupil defect, nerve fiber bundle defects on visual field, and sectoral optic disc pallor. MRI showed a large optic nerve mass and subsequent biopsy showed WHO grade 1 pilocytic astrocytoma. He was treated with radiation therapy. During week 5 of radiation therapy the patient developed decreased central vision and progressive proptosis. MRI showed enlargement of the heterogeneously enhancing mass, extending intracranially, with a rim of enhancement at the tumor margin. The patient subsequently underwent resection of the optic nerve from the globe to just short of the chiasm. Pathology showed numerous abnormally thickened blood vessels, pronounced vascular proliferation, and large regions of recent and remote hemorrhage infiltrating the intra-tumoral spaces and extending into the subarachnoid space. With the exception of a rim of enhancement of the tumor margin the enlarged tumor showed similar MRI characteristics, as seen initially, with markedly heterogenous enhancement, but was not characteristic of hemorrhage. Pathology remained grade I pilocytic astrocytoma. Conclusions, including unique features of the case(s): Uniquely, this is a rare case of WHO grade I pilocytic astrocytoma in an adult that exhibited indolent growth with progressive visual field loss for five years followed by rapid enlargement during radiation therapy due to intratumoral hemorrhage. Acute development of intratumoral hemorrhage, with or without prior radiation therapy, is rare. However, the hemorrhage within the tumor in our case was not well-delineated on magnetic resonance imaging, and this may represent a limitation of imaging in detecting this type of transformation. References: None. Keywords: Tumors, Orbit/ocular pathology, Neuroimaging Financial Disclosures: The authors had no disclosures. Grant Support: None. Contact Information: None provided. 200 | North American Neuro-Ophthalmology Society