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Radiology > BRAIN/SPINE
Ganglioglioma
Article Last Updated: Apr 20, 2006
AUTHOR AND EDITOR INFORMATION
Section 1 of 12  
Author: Anil Khosla, MBBS, Assistant Professor, Department of Radiology, Section of Neuroradiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, Veterans Affairs Medical Center of St Louis
Anil Khosla is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, American Society of Neuroradiology, North American Spine Society, and Radiological Society of North America
Editors: Mahesh R Patel, MD, Chief of MRI, Department of Radiology, Santa Clara Valley Medical Center; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; C Douglas Phillips, MD, Professor, Departments of Radiology, Neurosurgery, and Otolaryngology, University of Virginia Health Sciences Center; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; James G Smirniotopoulos, MD, Professor of Radiology, Neurology, and Biomedical Informatics, Chairman, Department of Radiology and Radiological Sciences, Uniformed Services University of the Health Sciences
Author and Editor Disclosure
Synonyms and related keywords:
brain tumor, spinal cord tumor, neural tumor, CNS tumor, brain neoplasm, spinal cord neoplasm, neural neoplasm, CNS neoplasm, central nervous system tumor, central nervous system neoplasm
Background
Ganglioglioma was first described by Courville in 1930 as a central nervous system neoplasm containing both astrocytic and neuronal components. Gangliogliomas may occur anywhere in the central nervous system but are not encountered commonly. Similar to other brain tumors, imaging techniques define the tumor location and its relationship to adjacent structures. Because of its relative rarity and nonspecific appearance, ganglioglioma is only infrequently considered a presurgical diagnosis.
Pathophysiology
Gangliogliomas are firm grayish tumors that may have cystic components. Tumors are mild-to-moderately cellular and slightly pleomorphic with rare mitotic figures. On light microscopy, atypical dysplastic neurons, astrocytes, and fibrovascular stroma are observed. Infrequently, anaplastic degeneration occurs and involves the astrocytic component. Neoplastic ganglion cells are large and mature and reveal intense immunoreactivity with synaptophysin, show expression of the stem cell epitope CD34, and are often binucleated. Biologic behavior is not predicted by histology, since many histologically anaplastic gangliogliomas do not demonstrate clinically aggressive behavior.
Most gangliogliomas are observed in the brain. Temporal lobes and cerebellar hemispheres are the most common locations. Gangliogliomas have been reported in unusual locations, such as the pineal gland, basal ganglia, hypothalamus, and optic chiasm. Rarely, they may also develop in the spinal cord.
Frequency
United States
Gangliogliomas represent approximately 0.4% of central nervous neoplasms and 1.3% of brain tumors. Only 1% of intramedullary spinal neoplasms are histologically gangliogliomas. Approximately 10% of primary brain tumors in children are gangliogliomas.
Mortality/Morbidity
Gangliogliomas are generally well-demarcated and slowly growing tumors. Recurrence is rare following gross total resection of the tumor. Radiation treatment is not indicated following gross total resection. Complete tumor resection is generally curative. Metastatic spread is extremely rare. Only a few reported cases describe benign gangliogliomas progressing to malignant gliomas.
Race
No racial predilection has been reported.
Sex
Male-to-female ratio is equal.
Age
Most gangliogliomas are observed in patients younger than 30 years. The age ranges from 2 months to 70 years.
Clinical Details
Presentation depends on patient age and the location and aggressiveness of the tumor. Most gangliogliomas are nonaggressive, and most patients present with long-standing progressive symptoms. Temporal lobe gangliogliomas usually present with temporal lobe seizures. Now that MR screening of seizure patients is more routine, these are increasingly identified on imaging. Gross total removal is the best chance for a cure.
Cerebellar lesions present with ataxia, headache, and hydrocephalus. Patients presenting with seizures have a better prognosis, since they are diagnosed and treated early.
Preferred Examination
MRI with contrast enhancement is more sensitive and specific than other imaging techniques in determining the presence and location of lesions and in characterizing the lesion's cystic and/or solid components.
Limitations of Techniques
Imaging appearances are nonspecific, and the diagnosis usually is established by histology and immunohistochemistry.
Oligodendroglioma
Other Problems to be Considered
Gangliocytoma
Low-grade gliomas
Dysembryonic neuroepithelial tumor
Oligodendroglioma (tumors heterogeneous in appearance; small samples may not include diagnostic ganglion cells)
Ganglionic cells may be mistaken for gemistocytic astrocytes (immunohistochemistry helps diagnosis)
Findings
Usually, plain films do not contribute to the diagnosis. Rarely, findings may be related to increased intracranial pressure. Occasional gangliogliomas are sufficiently calcified to be visible on plain radiographs.
Findings
On CT, tumors usually are well circumscribed and located peripherally. Imaging appearance is nonspecific. Grossly, one half of gangliogliomas show cystic areas, calcification, and enhancement.
- Most tumors are hypo-dense or iso-dense to brain parenchyma with poor contrast enhancement.
- Cystic tumors predominantly are found (with decreasing frequency) in the cerebellum, temporal, frontal, and parietal lobes.
- Solid tumors usually are seen in the temporal lobe.
- Cystic appearance varies from a single large cyst to a cyst with mural nodule to a multicystic mass.
- Solid tumors have more contrast enhancement.
- Punctate or flecklike calcification is seen in one third of tumors.
- Anaplastic tumors have a heterogeneous appearance with excellent contrast enhancement.
- Surrounding edema is unusual.
- Hemorrhage rarely is identified.
- Correlation between surrounding edema and anaplasia is described.
Degree of Confidence
Imaging patterns are nonspecific. Solid enhancing tumors in the temporal lobe in younger patients with seizures may suggest the diagnosis. In addition, ganglioglioma is the most common neoplastic cause of temporal lobe seizures.
False Positives/Negatives
- Low-grade gliomas may appear similar.
- Calcified lesions may mimic oligodendrogliomas.
- Cystic tumors may mimic juvenile pilocytic astrocytoma.
Findings
MRI is useful in differentiating the cystic and solid components of tumors (Images 1-2). Most tumors are hypo-intense on T1-weighted images and hyper-intense on T2-weighted images relative to gray matter. An isolated case report demonstrated leptomeningeal spread of the tumor. A proton MR spectroscopy signal from N-acetylaspartate is an endogenous marker for functioning neurons. The choline-to-creatine ratio is lower and the N-acetylaspartate-to-creatine ratio is higher in gangliogliomas than in gliomas. A high N-acetylaspartate-to-creatine ratio may be due to a neoplastic neuronal component.
Degree of Confidence
Imaging patterns are nonspecific. A solid enhancing tumor located in the temporal lobe with no surrounding edema in a younger patient with intractable seizures is highly suggestive of the diagnosis.
False Positives/Negatives
- Low-grade gliomas may appear similar.
- Differentiate calcified lesions from oligodendrogliomas.
- Cystic tumors may mimic juvenile pilocytic astrocytoma.
Findings
Ultrasonography is noncontributory to the diagnosis.
Findings
Nuclear medicine studies are not helpful in the diagnosis. Solid tumors may show increased radiotracer uptake on single-photon emission CT studies. In a small cohort, fluorodeoxyglucose-positron emission tomography and thallium Tl 201 single-photon emission CT reportedly have helped in preoperative grading of these tumors; however, this observation has not been substantiated.
Only limited information is available in the literature regarding fluorodeoxyglucose positron-emission tomography findings in these tumors. Grade I/II gangliogliomas showed hypometabolic or isometabolic changes.
Findings
Cerebral angiography provides no additional information apart from confirming the nonvascular nature of the tumors. Rarely, the enhancement pattern of the tumor may mimic a vascular malformation, and catheter angiography is required to exclude a vascular malformation.
Interventional imaging techniques have no role in the diagnosis or management of these tumors.
| Media file 1:
Axial MRI images (T1-weighted, T1-weighted with contrast, and T2-weighted) demonstrate a left superior medial frontal mixed solid and cystic mass that is surgically proven and typical ganglioglioma.
The solid anterior component is hypo-intense on the T1-weighted image, of intermediate intensity on the T2-weighted image, and reveals dense contrast enhancement. The cystic posterior component has low cerebrospinal fluidlike signal on the T1-weighted image and bright signal on the T2-weighted image with no contrast enhancement. Note that the tumor extends to a cortical surface, and no surrounding edema is seen. |
 |  View Full Size Image | |
Media type: MRI
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| Media file 2:
Axial MRI images (T2-weighted, T1-weighted, and T1-weighted with contrast) show a multiloculated, predominantly cystic right occipital mass that is surgically proven and typical ganglioglioma. The loculi are iso-intense to cerebrospinal fluid on both T1-weighted and T2-weighted images. Neither contrast enhancement nor surrounding edema is seen. |
 | View Full Size Image | |
Media type: MRI
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Ganglioglioma excerpt Article Last Updated: Apr 20, 2006
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