Ganglioglioma
General description
Gangliogliomas are rare, typically low-grade (<WHO Grade I) glioneuronal neoplasms thatly affect children and young adults and arise almost exclusively within the brain parenchyma.
Gangliogliomas account for approximately 0.4–3.8% of all primary intracranial tumors and up to 10% of pediatric cerebral neoplasms, with most arising in patients under 20 years of age. In a series of 348 pediatric cases, the mean age at diagnosis was 10.9 years (median 12.0), with 62.9% diagnosed after age 10; only 3.5% occurred in infants under one year. Although some pediatric series report a male predominance (male:female ratio 1.5–1.9:1), tumors involving the brainstem exhibit a near-equal sex distribution. In adult series, no significant gender predilection is noted.
Patients typically present with long-standing, nonfocal symptoms, most commonly seizures when tumors are temporal. Other symptoms reflect local mass effect—headache, focal deficits, or signs of increased intracranial pressure. Pediatric brainstem gangliogliomas may present with cranial neuropathies and ataxia.
References
- Dudley, Roy WR, et al. "Pediatric low-grade ganglioglioma: epidemiology, treatments, and outcome analysis on 348 children from the surveillance, epidemiology, and end results database." Neurosurgery 76.3 (2015): 313-320.
Cerebral mass
Gangliogliomas develop almost exclusively within the cerebral parenchyma. The temporal lobe is the single most common site, accounting for 43–79% of cases in pediatric series and 38.8% in adults. Other locations include the frontal (9.5–14.7%), parietal (9.5%), occipital lobes, cerebellum, brainstem (<5%), thalamus, and spinal cord (~3.5%).
Margins are generally well defined, with minimal or absent surrounding edema in most cases; moderate edema can occur.
Tumor morphology may be cystic, cystic-solid, or solid:
- Cystic dominant (≈15–20%) present as pure cystic lesions without solid enhancing components.
- Cystic-solid (≈46%) contain both fluid components and enhancing nodules or walls (mural nodules) that avidly enhance after contrast administration.
- Solid (≈54%) appear as homogeneous or heterogeneous soft-tissue masses.
Solid components of the gangliogliomas exhibit isointense to hypointense relative to gray matter on T1-weighted images, while T2-weighted image shows hyperintensity, reflecting low cellularity and mixed glioneuronal tissue. Gangliogliomas typically show facilitated diffusion (high ADC values) due to low cellularity; true diffusion restriction is rare and suggests higher grade or alternative diagnosis.
Approximately 32–52% demonstrate cystic areas; cyst fluid is typically hyperintense on T2 and hypointense on T1, occasionally with proteinaceous or hemorrhagic debris altering signal.
Calcifications are present in ~35–70% of cases, often peripheral or shell-like, best seen on CT as punctate or coarse hyperdensities, Blooming may correspond to calcification or hemosiderin from prior hemorrhage on T2* (GRE/SWI) images. Necrosis and hemorrhage are uncommon in gangliogliomas.
Cerebellar atrophy
In cerebellar gangliogliomas, ipsilateral cerebellar atrophy is characteristically common.