Ganglioglioma


KEY FACTS

Terminology

  • Well-differentiated, slowly growing neuroepithelial tumor composed of neoplastic ganglion cells and neoplastic glial cells

  • Most common neoplastic cause of temporal lobe epilepsy (TLE)

Imaging

  • Best diagnostic clue: Partially cystic, enhancing, cortically based mass in child/young adult with TLE

  • Can occur anywhere, but most commonly superficial hemispheres, temporal lobe (> 75%)

  • Circumscribed cyst with mural nodule most common

  • May be solid and appear well circumscribed

  • Calcification is common (up to 50%)

  • Superficial lesions may expand cortex, remodel bone

  • ~ 50% enhance

  • Protocol advice: Contrast-enhanced MR to include coronal T2 images for better evaluation of temporal lobes

Top Differential Diagnoses

  • Pleomorphic xanthoastrocytoma

  • Dysembryoplastic neuroepithelial tumor

  • Astrocytoma

  • Oligodendroglioma

  • Neurocysticercosis

Pathology

  • WHO grade I or II (80% grade I)

  • Uncommon: Anaplastic ganglioglioma (WHO III)

  • Rare: Malignant with glioblastoma multiforme-like glial component (WHO IV)

Clinical Issues

  • Occurs at all ages (peak: 10-20 years)

  • Most common mixed neuronal-glial tumor

  • Cortical dysplasia is commonly associated with ganglioglioma

  • Excellent prognosis if surgical resection complete

Coronal graphic shows a discrete cystic and solid temporal lobe mass expanding the overlying cortex. Calvarial remodeling is seen, typical of a superficially located ganglioglioma. Gangliogliomas are the most common tumors to cause temporal lobe epilepsy.

Coronal T1WI C+ MR in a young adult with temporal lobe epilepsy shows a circumscribed, cystic, and solid temporal lobe mass with intense enhancement of the mural nodule
. This is the classic enhancement pattern of a ganglioglioma.

Axial CT shows a partially calcified frontal lobe mass
in a 25-year-old patient with headaches and seizures. The lack of surrounding edema is typical for ganglioglioma. Imaging mimics an oligodendroglioma. Calcification is seen in 30-50% of gangliogliomas.

Coronal T1WI C+ MR shows subtle enhancement
within a right temporal lobe ganglioglioma in a female patient with seizures. The differential diagnosis for this lesion includes DNET, astrocytoma, PXA, and oligodendroglioma.

TERMINOLOGY

Abbreviations

  • Ganglioglioma (GG)

Definitions

  • Well-differentiated, slowly growing neuroepithelial tumor composed of neoplastic ganglion cells and neoplastic glial cells

  • Most common neoplasm to cause temporal lobe epilepsy (TLE)

IMAGING

General Features

  • Best diagnostic clue

    • Partially cystic, enhancing, cortically based mass in child/young adult with TLE

  • Location

    • Can occur anywhere, but most commonly superficial hemispheres, temporal lobe (> 75%)

      • Frontal and parietal lobes next most common

    • Rare locations: Brainstem, cerebellum, pineal region, optic nerve/chiasm, intraventricular, pituitary axis, spinal cord, cranial nerves

  • Size

    • Variable in adults, typically 2-3 cm

    • Larger in children, typically > 4 cm

    • Up to 6 cm reported

  • Morphology

    • 3 patterns

      • Most common: Circumscribed cyst with mural nodule

      • Solid tumor (often thickens, expands gyri)

      • Uncommon: Infiltrating, poorly delineated mass

    • Calcification is common (up to 50%)

    • In younger patients (< 10 years), gangliogliomas are larger and more cystic

CT Findings

  • NECT

    • Variable density

      • 40% hypodense

      • 30% mixed hypodense (cyst), isodense (nodule)

      • 15% isodense or hyperdense

    • Ca++ common (35-50%)

    • Superficial lesions may expand cortex, remodel bone

    • Hemorrhage is rare

  • CECT

    • ~ 50% enhance

      • Variable; moderate and uniform to heterogeneous

      • Can be solid, rim, or nodular

      • Often shows cyst with enhancing nodule

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