Gangliocytoma

Gangliocytomas are rare indolent CNS tumours (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 tumours are defined by the presence of displaced ganglion cells (large mature neurones that show cytological or architectural abnormalities).

On imaging, these tumours are usually characterised by cortical solid lesions with little associated mass effect and minimal or no surrounding vasogenic oedema. 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 tumours. They tend to be diagnosed in children and young adults ².

Clinical presentation

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

Pathology

Gangliocytomas may arise anywhere within the neuroaxis ⁴.

Microscopic appearance

The tumour is composed of abnormal large mature neurones, usually with a multipolar morphology ⁵. Some neurones 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 oedema. 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 tumours tend to grow slowly and do not undergo anaplastic change. Resection is curative.

Differential diagnosis

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