Vein of Galen Aneurysm
Joseph Junewick, MD FACR
over 7 years ago
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Joseph Junewick, MD FACR
|Diagnostic Category: Neoplasia Malignant
|Created: over 6 years ago
|Updated: over 6 years ago
6 year old male with seizure.
CT – Isodense or minimally hypodense lesion in the anterior corpus callosum.
MR – Focal lesion in the genu of the corpus callosum which is hyperintense on T1, T2, T2-FLAIR and post-gadolinium sequences.
Neurocytomas are neural tumors which are histologically similar to oligodendrogliomas. Neurocytomas often arise from the septum pellucidum or ventricular wall and extend into the lateral or third ventricles. Extraventricular neurocytomas have been reported in the brain parenchyma, the cerebellum, and the spinal cord. Central neurocytomas constitute less than 1% of all intracranial tumors. The age at presentation varies widely (8 days to 67 years, with a mean of 29 years). There is no gender predilection. A relatively short clinical course is typical, with the symptoms being related to increased intracranial pressure, mental status changes, visual deficits (secondary to papilledema), or hormonal changes (particularly for those lesions involving the third ventricle). In rare cases, these tumors may be associated with sudden death secondary to acute ventricular obstruction.
The histogenesis of central neurocytomas remains unclear. Although the immunohistochemical features support a neuronal lineage, there are recent cell-culture investigations that indicate that the tumors may be derived from bipotential progenitor cells that are capable of both neuronal and glial differentiation. These cells may be located in the subependymal plate, which would provide a possible explanation for why some neurocytomas are extraventricular. Neurocytomas usually express immunoreactivity for synaptophysin and neuron-specific enolase, both markers for neuronal differentiation, which also aids in differentiating these tumors from oligodendrogliomas.
On CT images, the lesions are usually hyperdense compared with the brain parenchyma. Cyst-like areas are noted in two-thirds of cases with imaging studies. Calcification, usually punctate in character, is present in half of the cases. Moderate enhancement is typical. On MR imaging, central neurocytoma is isointense on T1, variably hyperintense on T2 (related to cystic change, hemorrhage and/or clacification) and enhances.
Prognosis of this tumor is typically favorable. Gross total surgical resection is the treatment of choice and typically curative. Radiation therapy, chemotherapy, or stereotactic radiosurgery may be used if resection is incomplete. A poorer clinical outcome is also usually seen in patients with central neurocytomas that undergo extraventricular extension.
Shin NH, Lee HK, Khang SK, Kim DW, Jeong AK, et al. Neuronal Tumors of
the Central Nervous System: Radiologic Findings and Pathologic Correlation RadioGraphics (2002); 22:1177–1189.
Koeller KK, Sandberg GD. Cerebral Intraventricular Neoplasms: Radiologic-Pathologic Correlation. Radiographics (2002), 22, 1473-1505.