Description
Desmoplastic infantile ganglioglioma (DIG) is a rare, generally benign (WHO grade I), mixed neuronal-glial tumour, typically occurring in infancy and early childhood. It is a part of the broader family of paediatric tumours and falls under the umbrella of glioneuronal tumours.
Pathogenesis
The pathogenesis of DIGs remains unclear. They are thought to originate from neuroepithelial precursors, similar to other neuronal and mixed neuronal-glial tumours.
Epidemiology, Risk Factors & Associations
- Primarily occur in infants and young children, usually before the age of 2 years.
- There is no known gender predilection.
- No identified genetic or environmental risk factors as of the current literature.
Clinical Features
- Increasing head size secondary to the large size of the tumour and associated hydrocephalus.
- Variable seizure activity.
- Developmental delay and irritability may be seen.
Complications
- Hydrocephalus due to the large size of the tumour causing obstruction of CSF pathways.
- Neurological deficits and developmental delay.
Pathological Features
Histopathology
- Macroscopic: Tumours are typically large, cystic, and well-circumscribed with a peripheral solid component attached to the meninges.
- Microscopic: Characterised by a desmoplastic reaction (fibrosis) in the leptomeninges and superficial cortex, with an admixture of astrocytic and neuronal elements.
Serology
No specific serological markers.
Biochemistry
No specific biochemical markers.
Radiological Features
General Features
- Exceptionally large, cystic, and often multilobulated tumour, involves both cortex and meninges.
- Frontal and parietal lobes are most common sites.
- Calcification is infrequent.
- The dural tail sign, typically associated with meningiomas, may be seen due to the intense desmoplasia of these tumours.
- The tumour is often attached to the dura and may lead to scalloping of the underlying bone.
CT
- Non-contrast: Solid component usually peripherally based and isodense to slightly hyperdense with the cerebral cortex. Calcification is infrequent.
- Contrast-enhanced: Variable enhancement of solid components and possibly demonstration of a dural tail.
MRI
- T1: Isointense to hypointense compared to grey matter.
- T2: Isotense solid component. Hyperintense signal due to the cystic nature of the tumour.
- T1 C+: Variable enhancement of solid components.
- DWI/ADC: No restricted diffusion.
PET FDG
Not typically performed in this condition.
Grading and Staging
Desmoplastic infantile gangliogliomas are typically WHO grade I tumours. No specific staging system exists.
Diagnosis
The diagnosis is typically made based on a combination of clinical presentation, imaging characteristics, and histopathological confirmation following surgical resection.
Differential Diagnosis
- Pilocytic astrocytoma: Commonly presents in children, usually with a cystic component and an enhancing mural nodule. Unlike DIG, they often occur in the cerebellum and do not cause scalloping of the underlying bone.
- Glioblastoma: Although rare in this age group, it may present with a large cystic and enhancing mass. However, these are typically more aggressive with a worse prognosis.
Management
Surgical resection is typically the treatment of choice. Given the benign nature of the tumour, adjuvant therapy is usually not necessary, and complete resection usually leads to a good prognosis.