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Gangliogliomas are uncommon, usually low-grade, CNS tumors. Epilepsy is a common clinical presentation and this tumor has a typical occurrence in the temporal lobes, although they have been described in all parts of the central nervous system.
Their appearance on imaging is very variable: from a partially cystic mass with an enhancing mural nodule (~45% of cases) to a solid mass expanding the overlying gyrus. Contrast enhancement is variable.
Children and young adults are usually affected, and no gender predominance is recognized. It accounts for around 2% (from 0.4-3.8%) of all primary intracranial tumors, and up to 10% of primary cerebral tumors in children.
The most common presentation is with temporal lobe epilepsy, presumably due to the temporal lobes being a favored location.
Gangliogliomas are most frequently found in the temporal lobes (70%) 6,9 but do occur anywhere in the central nervous system.
The majority are indolent and designated as WHO grade 1 tumors in the current (2021) WHO classification of CNS tumors) although in a minority (e.g. 5%) of cases higher grade features are present 10. These have previously been called "anaplastic gangliogliomas" although no clear grading criteria for higher-grade tumors exist at present10.
Gangliogliomas, as their name suggests, are composed of two cell populations:
- ganglion cells (large mature neuronal elements): ganglio-
- neoplastic glial element: -glioma
- primarily astrocytic, although oligodendroglial or pilocytic astrocytoma components are also encountered 9
The proportion of each component varies widely, and it is the grade of the glial component that determines biological behavior.
Neuronal origin is demonstrated by positivity to neuronal markers 9:
- synaptophysin: positive
- neurofilament protein: positive
- MAP2: positive
- chromogranin-A: positive (usually negative in normal neurons) 9
- CD34: positive in 70-80%
The glial component may also show cytoplasmic positivity for GFAP.
- BRAF V600E mutations are encountered in 20-60% of cases 9
- IDH: negative (if positive then the tumor is most likely a diffuse glioma) 9
Imaging findings mirror the various patterns of growth which these tumors may demonstrate and thus their appearance is very variable. A partially cystic mass with an enhancing mural nodule is seen in ~45% of cases. They may also simply present as a solid mass expanding the overlying gyrus. An infiltrating mass is uncommon and may reflect a higher grade.
Findings are of a mass that is often non-specific. General features include:
- iso- or hypodense
- frequently calcified ~35%
- bony remodeling or thinning can indicate the slow-growing nature of a tumor
- enhancement is seen in approximately 50% of cases (involving the solid non-calcified component)
Reported signal characteristics include:
- solid component iso to hypointense
T1 C+ (Gd)
- solid component variable contrast enhancement
- hyperintense solid component
- variable signal in the cystic component depending on the amount of proteinaceous material or the presence of blood products
- peritumoral FLAIR/T2 edema is distinctly uncommon
- calcified areas (common) will show blooming signal loss
Treatment and prognosis
Local resection is the treatment of choice and determines prognosis. In the brain, where a reasonable resection margin can be achieved, the prognosis is good, with recurrence-free survival reported to be 97% at 7.5-year follow-up 9.
In contrast, in the spinal cord where complete resection is often not possible without devastating deficits, local recurrence is very common.
If only incomplete resection is achievable, or tumor recurrence occurs then radiotherapy may be of some benefit.
The main differential diagnosis is that of other cortical tumors, with helpful distinguishing features including 1-6:
dysembryoplastic neuroepithelial tumors (DNET)
- contrast enhancement uncommon
- 'bubbly appearance' common
pleomorphic xanthoastrocytoma (PXA)
- contrast enhancement prominent
- dural tail sign is often seen
- calcifications common
desmoplastic infantile astrocytoma and ganglioglioma
- young children
- dural involvement prominent
- large often multiple lesions
If in the spinal cord consider:
- 1. Kwon J, Kim I, Cheon J et al. Cerebellopontine Angle Ganglioglioma: MR Findings. AJNR Am J Neuroradiol. 2001;22(7):1377-9. PMC7975207 - Pubmed
- 2. Patel U, Pinto RS, Miller DC et-al. MR of spinal cord ganglioglioma. AJNR Am J Neuroradiol. 1998;19 (5): 879-87. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 3. Provenzale J, Ali U, Barboriak D, Kallmes D, Delong D, McLendon R. Comparison of Patient Age with MR Imaging Features of Gangliogliomas. AJR Am J Roentgenol. 2000;174(3):859-62. doi:10.2214/ajr.174.3.1740859 - Pubmed
- 4. Castillo M. Gangliogliomas: Ubiquitous or Not? AJNR Am J Neuroradiol. 1998;19(5):807-9. PMC8337568 - Pubmed
- 5. Shin JH, Lee HK, Khang SK et-al. Neuronal tumors of the central nervous system: radiologic findings and pathologic correlation. Radiographics. 22 (5): 1177-89. Radiographics (full text) - Pubmed citation
- 6. Zoran Rumboldt, Mauricio Castillo, Benjamin Huang et al. Brain Imaging with MRI and CT. (2012) ISBN: 9781139576390 - Google Books
- 7. Song JY, Kim JH, Cho YH et-al. Treatment and outcomes for gangliogliomas: a single-center review of 16 patients. Brain Tumor Res Treat. 2014;2 (2): 49-55. doi:10.14791/btrt.2014.2.2.49 - Free text at pubmed - Pubmed citation
- 8. Koeller KK, Henry JM. From the archives of the AFIP: superficial gliomas: radiologic-pathologic correlation. Armed Forces Institute of Pathology. Radiographics. 2001;21 (6): 1533-56. doi:10.1148/radiographics.21.6.g01nv051533 - Pubmed citation
- 9. International Agency for Research on Cancer, Otmar D. Wiestler. WHO Classification of Tumours of the Central Nervous System. (2016) ISBN: 9789283244929 - Google Books
- 10. Solomon D, Varlet P, Blumcke I, Capper D, Gupta K, Rosette-forming glioneuronal tumour. In: WHO Classification of Tumours Editorial Board. Central nervous system tumours. Lyon (France): International Agency for Research on Cancer; 2021. . (WHO classification of tumours series, 5th ed.; vol. 6). https://publications.iarc.fr/601