Discrepancy between radiological and histological findings in ganglioglioma of the optic chasm: Case report
- Department of Neurosurgery, Shiga Medical Center for Adults, Shiga, Japan
- Shiga Medical Center Research Institute, Shiga, Japan
Department of Neurosurgery, Shiga Medical Center for Adults, Shiga, Japan
DOI:10.4103/sni.sni_289_16Copyright: © 2017 Surgical Neurology International This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Yoshito Sugita, Masahiro Sawada, Toshihiro Munemitsu, Tatsuya Higashi, Masato Hojo. Discrepancy between radiological and histological findings in ganglioglioma of the optic chasm: Case report. 11-Jul-2017;8:146
How to cite this URL: Yoshito Sugita, Masahiro Sawada, Toshihiro Munemitsu, Tatsuya Higashi, Masato Hojo. Discrepancy between radiological and histological findings in ganglioglioma of the optic chasm: Case report. 11-Jul-2017;8:146. Available from: http://surgicalneurologyint.com/surgicalint-articles/discrepancy-between-radiological-and-histological-findings-in-ganglioglioma-of-the-optic-chasm-case-report/
Background:Gangliogliomas involving the optic nerve or chiasm are extremely rare tumors, which can be confused radiologically with other neoplasms. α-[N-methyl-11C]-methylaminoisobutyric acid (11C-MeAIB) is a new artificial amino acid positron emission tomography (PET) tracer, which is metabolically more stable in vivo and may be more specific for tumors than 11C-methionine. However, the utility of 11C-MeAIB PET in the diagnosis of brain tumors has not yet been reported.
Case Description:A 26-year-old man presented with visual field defects and headache, and magnetic resonance imaging demonstrated a suprasellar mass involving the optic chiasm. A biopsy and partial tumor resection were performed via an interhemispheric approach. We diagnosed the tumor as ganglioglioma (WHO grade I) involving the optic chiasm. Although this lesion was histologically benign, 11C-MeAIB PET, 2-deoxy-2-[18F] fluoro-D-glucose (18F-FDG) PET and proton magnetic resonance spectroscopy indicated malignant features.
Conclusion:The discrepancy between radiological and histological findings implies that this new amino acid tracer PET may have a limitation in the diagnosis of gangliogliomas. Although further study is necessary, gangliogliomas should be included in the differential diagnosis of suprasellar tumors, even if PET findings show malignant features.
Keywords: Ganglioglioma, MeAIB PET, optic chiasm
Gangliogliomas, which are composed of both neuronal and glial components, are rare and account for only 0.3–1.3% of all brain tumors.[
α-[N-methyl-11C]-methylaminoisobutyric acid (11C-MeAIB) is a new artificial amino acid PET tracer, which is metabolically more stable in vivo and may be more specific for tumors than 11C-methionine (11C-MET). However, the utility of 11C-MeAIB PET in the diagnosis of brain tumors has not yet been reported. Here, we report the first case of ganglioglioma of the optic chiasm, which was evaluated by 11C-MeAIB PET, 2-deoxy-2-[18F] fluoro-D-glucose (18F-FDG) PET and MRS. We also show discrepancies between radiological and histological findings in this lesion.
A 26-year-old man presented with a 1-month history of progressive visual field defects and headache. Neuro-ophthalmological examination revealed temporal hemianopsia and bilateral papilledema. As part of the diagnostic work-up at our institution, computed tomography (CT), magnetic resonance imaging (MRI), MRS (Ingenia 3.0T, Philips Medical System, Amsterdam, Nederland), and PET (GE Advance, GE Healthcare, Waukesha WI, USA) were performed. CT revealed a mixed-dense suprasellar mass lesion without signs of calcification, as well as hydrocephalus caused by obstruction of the foramina of Monro. MRI demonstrated a suprasellar mass involving the optic chiasm, which had cystic components. The lesion was hypointense on T1-weighted images (WI), hyperintense on T2-WI, and showed marked enhancement after the administration of contrast material [
11C-MeAIB PET revealed remarkably high uptake of MeAIB] standardized uptake value (SUV) max = 9.8] consistent with enhanced lesion on MRI, and lesion to gray matter ratio (LGR) was 56.9 [
A biopsy and partial tumor resection were performed via an interhemispheric approach. The intraoperative findings were that the tumor originated from the optic chiasm without a clear plane of dissection. Therefore, total resection was abandoned to avoid damage to the optic nerve. Histopathological evaluation of the tumor revealed that the tumor comprised both neoplastic glial and ganglion cells. Immunohistochemical staining demonstrated that dysmorphic ganglion cells were positive for synaptophysin, and pleomorphic glial cells were positive for glial fibrillary acid protein (GFAP). No high-grade neoplastic feature was detected, and Ki-67 immunoreactivity was less than 3%. We diagnosed the tumor as ganglioglioma (WHO grade I) involving the optic chiasm. Although 11C-MeAIB PET, 18F-FDG PET, and MRS indicated malignant features, the lesion was histologically benign. Because ventricular dilatation did not improve, a ventriculoperitoneal shunt was performed. Postoperative course was uneventful. Although the role of postoperative radiotherapy is controversial, most cases of optic gangliogliomas reported in the literature have received adjuvant radiation when only biopsy or subtotal resection could be performed.[
Gangliogliomas of the optic chiasm are extremely rare and radiologically difficult to distinguish from other suprasellar tumors.[
It is well known that 11C-MET PET is more sensitive for brain tumors than 18F-FDG-PET. Im et al. have reported a case of cerebral ganglioglioma, which showed hypometabolism on 11C-MET PET.[
MRS provides useful information on tumor metabolism and has been proposed as a method for tumor grading.[
We have shown the first case of ganglioglioma of the optic chiasm, which was evaluated by 11C-MeAIB PET, 18F-FDG PET, and MRS. Although this lesion was histologically benign, 11C-MeAIB PET, 18F-FDG PET, and MRS indicated malignant features. Since this report shows only one case, further study is necessary to confirm the advantages and limitations of these diagnostic modalities. Gangliogliomas should be included in the differential diagnosis of suprasellar tumors, even if PET and MRS findings show malignant features.
The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
We thank Shigeru Tanaka, Miki Ito, Yusuke Chaya, and Takuma Hayashi for technical help.
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