A 13-year-old girl with a right intraorbital optic nerve glioma (ONG) was referred to our glaucoma clinic because of uncontrolled intraocular pressure (IOP) in her right eye. The IOP reached as high as 80 mmHg. Several months earlier, she had undergone stereotactic image-guided robotic radiosurgery using the CyberKnife for her ONG; the mass had become smaller after treatment. Her visual acuity was no light perception. Slit lamp examination revealed rubeosis iridis, a swollen pale optic disc, and vitreous hemorrhage. After medical treatment, the IOP decreased to 34 mmHg, and no pain was reported. Although the mass effect of an ONG can cause neovascular glaucoma (NVG), this case shows that stereotactic radiosurgery may also cause NVG, even after reducing the mass of the tumor. Patients who undergo radiosurgery targeting the periocular area should be followed carefully for complications.
Adolescent ; Diagnosis, Differential ; Female ; Fluorescein Angiography ; Follow-Up Studies ; Fundus Oculi ; Glaucoma, Neovascular/diagnosis/*etiology/physiopathology ; Glioma/diagnosis/*surgery ; Gonioscopy ; Humans ; Intraocular Pressure ; Magnetic Resonance Imaging ; Optic Nerve Neoplasms/diagnosis/*surgery ; Radiosurgery/*adverse effects

OBJECTIVETo study the clinicopathologic features of pilomyxoid astrocytoma (PmA).

METHODSThe clinical and pathologic features in 3 cases of PmA were analyzed. Immunohistochemical study for glial fibrillary acidic protein (GFAP), CD34 and Ki-67 was performed on paraffin-embedded sections by standard EnVision method.

RESULTSAll the 3 cases occurred in female patients at the age of 10 months, 10 years and 19 years respectively. Two cases were located in the third ventricle, while the remaining case was located at the optic pathway. Histologically, the tumor was composed of bipolar spindle cells setting in a strikingly mucinous background. There was a marked proliferation of vessels within the tumor. In some areas, the tumor cells exhibited an angiocentric growth pattern. The biphasic pattern noted in a classic pilocytic astrocytoma was not found in PmA. Rosenthal fibers and eosinophilic granular bodies were also not identified. Immunohistochemcal study showed that the tumor cells were diffusely positive for GFAP. The Ki-67 labeling index measured less than 1%. CD34 highlighted mainly the vascular networks.

CONCLUSIONSPmA is a distinctive variant of pilocytic astrocytoma with subtle histologic differences. Compared with conventional pilocytic astrocytoma, PmA behaves more aggressively. Some cases tend to occur in older children and adolescents. Immunohistochemical study for GFAP is helpful in differential diagnosis.

Antigens, CD34 ; metabolism ; Astrocytoma ; metabolism ; pathology ; surgery ; Cerebral Ventricle Neoplasms ; metabolism ; pathology ; surgery ; Child ; Diagnosis, Differential ; Female ; Follow-Up Studies ; Glial Fibrillary Acidic Protein ; metabolism ; Humans ; Immunohistochemistry ; Infant ; Ki-67 Antigen ; metabolism ; Magnetic Resonance Imaging ; Optic Nerve Glioma ; metabolism ; pathology ; surgery ; Third Ventricle ; metabolism ; pathology ; Tomography, X-Ray Computed ; Young Adult