Gangliocytoma

Gangliocytomas are rare indolent CNS tumors (WHO grade I), primarily encountered in children, and frequently discovered as the cause of epilepsy. 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.

Terminology

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

Epidemiology

Gangliogliomas account for 0.1-0.5% of all brain tumors. They tend to be diagnosed in children and young adults ².

Clinical presentation

No clinical differences between gangliogliomas and gangliocytomas are recognized. Tumors in the cerebral cortex present most commonly with epilepsy ⁴.

Pathology

Gangliocytomas may arise anywhere within the neuroaxis ⁴.

Microscopic appearance

The tumor is composed of abnormal large mature neurons, usually with a multipolar morphology ⁵. Some neurons are binucleated ⁵. The key feature in distinguishing gangliocytomas from gangliogliomas is identifying a lack of neoplastic glial cells.

Immunophenotype

• synaptophysin: positive
• neurofilament: positive
• chromogranin-A: positive
• MAP2: positive
• GFAP: negative

Radiographic features

Appearances of gangliocytomas are indistinguishable from gangliogliomas ⁵.

CT

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

MRI

• 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

Treatment and prognosis

These tumors tend to grow slowly and do not undergo anaplastic change. Resection is curative.

Differential diagnosis

• ganglioglioma
• cortical dysplasia
• dysembryoplastic neuroepithelial tumor (DNET)