Gangliogliomas
Gangliogliomas are a group of slowly growing neoplasms composed of both neural and glial elements. Most gangliogliomas are supratentorial in location, and the temporal lobes are the predominant site. However, they can also arise in the cerebellum, brainstem, suprasellar region, and spinal cord.
Desmoplastic infantile ganglioglioma, also known as a DIG tumor, is a form of ganglioglioma occurring in young patients, typically less than 2 years of age. The majority of patients with this tumor present around 5-6 months of age. There is no gender predilection. DIG tumors are typically large, supratentorial, heterogeneously-appearing mass lesions with both solid and cystic components, located predominantly in the temporal lobes.
The predominant histopathologic feature is striking desmoplasia, characterized by a dense stroma incorporating glial, neuronal, and fibroblastic elements. This tumor may fill in the subarachnoid space and can extend along perivascular spaces. The DIG tumor is identified with intensely positive GFAP immunohistochemistry as well as positive trichrome stain due to the abundant collagen. Although the bulk of the DIG is superficial and seemingly well demarcated, some lesions include densely cellular focally infiltrative regions resembling a primitive neuroectodermal tumor. Nevertheless, the overall prognosis is favorable, and most patients have prolonged survivals after surgical excision of the DIG tumor.
Radiologic Overview:
The characteristic lesion of desmoplastic infantile ganglioglioma is a solid or partially cystic supratentorial, heterogeneous enhancing mass lesion, usually located in the temporal lobe of a young child or early adolescent.
On CT examination, this lesion may appear hypodense with both cortical and white matter involvement. There may be sulcal effacement and midline shift, depending on the size of the lesion. There usually is heterogeneous contrast enhancement of this lesion.
On MRI, the cystic component of the lesion will be dark on T1, bright on T2, and low signal on FLAIR images. There usually is adjacent vasogenic edema involving the cortical gray and white matter, which is bright signal on the FLAIR sequence. Again, the DIG tumor is characteristically located in the frontotemporal lobes.
Key points:
Rare pediatric brain tumor accounting for less than 1% of all cerebral neoplasms.
Massive, partially cystic tumor occurring predominantly in the frontotemporal lobes in a child less than 1-2 years of age.
Favorable prognosis after surgical resection
References:
Atlas, Scott W., ed. Magnetic Resonance Imaging of the Brain and Spine. 2nd Edition: New York, NY: Lippincott-Raven Publishers. 1996.
Barkovich, A. James. Pediatric Neuroimaging. 3rd Edition: Philadelphia, PA: Lippincott Williams & Wilkins. 2000.
Vandenberg, SR. "Desmoplastic infantile ganglioglioma and desmoplastic cerebral astrocytoma of infancy." Brain Pathology. 1993;3:275-281.
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