Gangliocytoma

Last revised by Frank Gaillard on 1 Oct 2023

Gangliocytomas are rare indolent CNS tumors (WHO grade 1), primarily encountered in children, and frequently discovered as the cause of epilepsy. They are considered one of the long-term epilepsy-associated tumors (LEATs).

They differ from gangliogliomas by the absence of neoplastic glial cells, although both tumors are defined by the presence of displaced ganglion cells (large mature neurons that show cytological or architectural abnormalities).

On imaging, these tumors are usually characterized by cortical solid lesions with little associated mass effect and minimal or no surrounding vasogenic edema. Calcification and cyst formation can occur, and contrast enhancement is generally present.

Gangliocytomas should not be confused with dysplastic cerebellar gangliocytoma of the cerebellum, better known as Lhermitte-Duclos disease.

Gangliocytomas account for 0.1-0.5% of all brain tumors but 1-3% of tumors in epilepsy series 5. They tend to be diagnosed in children and young adults, with a peak age between 10 and 30 years of age 6.

No clinical differences between gangliogliomas and gangliocytomas are recognized. Tumors in the cerebral cortex, particularly the temporal lobe, present most commonly with epilepsy which is often lonstanding at the time of diagnosis 4,6.

Gangliocytomas may arise anywhere within the neuroaxis, however, over 80% are found in the temporal lobes 4-6.

The tumor is composed of abnormal large mature neurons, usually with a multipolar morphology 5. Some neurons are binucleated and cytoplasmic vacuolization or ballooning is seen 5. Microcalcification can also be seen 5.

The key feature in distinguishing gangliocytomas from gangliogliomas is identifying a lack of neoplastic glial cells. Similarly, ensuring no small round blue cell component or neuroblasts are seen is important to exclude more aggressive tumors (such as medulloblastoma and neuroblastoma) which can have similar appearing ganglion cells 5.

The pattern of immunostaining is consistant with neuronal components 5,6.

Appearances of gangliocytomas are indistinguishable from gangliogliomas 5,6. They tend to occur in the cortex, most often in the temporal lobes. Because of cortical location and slow growth, calvarial remodeling may be seen in some cases 6.

Gangliocytomas typically appears hyperattenuating on non-contrast imaging. They usually only have little associated mass effect and minimal or no surrounding vasogenic edema. Calcification and cyst formation can occur 1.

Gangliocytomas often have cystic and solid components and may demonstrate calcifications 6.

  • T1: solid components typically hypointense

  • T2: solid components are typically mildly hypointense 2; cystic areas are hyperintense; calcification if present can be hypointense

  • T1 C+ (Gd): solid components enhance

  • T2*/SWI: signal loss due to calcification

These tumors tend to grow slowly and do not undergo anaplastic change, unlike gangliogliomas that can (rarely) have higher grade glial components. Resection is curative with a 7.5 year progression-free survival rate of 94% 6.

The differential diagnosis is primarily that of other long-term epilepsy-associated tumors (LEATs) including:

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Cases and figures

  • Figure 1: histology
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  • Case 1
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  • Case 2
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  • Case 3
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