Parietal anaplastic ganglioglioma in a 3-year-old girl

Clinical History

A 3-year-old-girl presented with headaches and partial complex seizures for a few months. There were findings suggestive of increased intracranial pressure.

Imaging Findings

An extensive mass located in the left parietal region with ill-defined borders was demonstrated, with involvement of the left thalamus. The mass had heterogeneous signal intensity, predominantly isointense on T1WI and T2WI, with cystic/necrotic zones and bleeding in the posterior portion of the tumour. It demonstrated mild / moderate perilesional oedema predominantly in the upper parietal region, which demonstrated restriction of diffusion. The lesion impinged on the body of the left lateral ventricle, causing moderate dilation of the left occipital and temporal horns. On T1FS+Gd the lesion demonstrated moderate heterogeneous enhancement, mainly posteriorly. Diffusion-weighted sequences showed restricted diffusion in the perilesional oedema. On spectroscopy, there is a marked increase in the choline peak, with a decrease in the N-acetylaspartate and Cr peaks (tumoral pattern).

Discussion

Gangliogliomas are tumours in which nerve and glial cells, usually astrocytes, participate in the neoplastic process; in this sense, they differ from most primary CNS neoplasms in which only the glial cells show neoplasia. Gangliogliomas are uncommon tumours, constituting approximately 3% of brain tumours in children and approximately 6% of supratentorial paediatric brain tumours; they are found in older children and young adults more frequently than younger children or infants [1].
The best diagnostic imaging clue is a partially cystic, enhancing, cortically-based mass in child/young adult with temporal/parietal lobe epilepsy. A cyst with an enhancing mural nodule is classic, but nonspecific for ganglioglioma. There are 3 morphologic patterns [1, 2]:
- The most common: Circumscribed cyst + mural nodule
- Solid tumour (often thickens, expands gyri)
- Uncommon: Infiltrating, poorly-delineated mass (our case)

CT findings are of a mass which is often non-specific. General features include an iso- or hypodense nodule-mass which is frequently calcified (35%). Bony remodelling or thinning can indicate the slow growing nature of the tumour. Enhancement is seen in approximately 50% of cases (involving the solid non-calcified component) [1, 3, 4].

On MRI, the ganglioglioma may have sharply or poorly defined margins. The tumour may be solid, cystic, cystic with a mural nodule, or have the appearance of many small cysts. Signal intensity on T1-weighted sequences is variable (and often mixed); T2-weighted sequences generally reveal variable signal intensity in the cystic component depending on the amount of proteinaceous material or presence of blood products. Regions of slight T1 hyperintensity, probably representing calcification, may be helpful in identifying these neoplasms. Solid portions of the tumour enhance variably. On T2* calcified areas may show blooming. Solid portions of the tumour enhance variably. Usually there is not restriction on DWI images, but reduced diffusion in solid components can be shown. Spectroscopy demonstrates a choline peak with decreased n-acetyl-aspartate, a pattern suggestive of tumour. The peripheral location within the hemispheres and the erosion of the adjacent calvarium can be helpful in making the diagnosis of ganglioglioma.

Symptoms are site-specific, but are typically long-standing. Ganglioglioma is the most common tumour associated with chronic temporal lobe epilepsy. [1, 4].
Surgical resection is treatment of choice. Radiation therapy and/or chemotherapy may be helpful for aggressive or unresectable tumours [4].

Differential Diagnosis List

Final Diagnosis

Parietal anaplastic ganglioglioma

URL:	https://www.eurorad.org/case/14890
DOI:	10.1594/EURORAD/CASE.14890
ISSN:	1563-4086