Cortically Based Brain Neoplasms

• Astrocytoma May extend to cortex. Minimal or no enhancement or edema in low-grade astrocytomas. Calcification is uncommon.
• Oligodendrolioma: Slowly growing, well-differentiated neoplasms. Diffusely infiltrating, but appear well-circumscribed. Calcifications are seen in 80% of cases.
• Ganglioglioma: Well-circumscribed cystic lesion with nodule and minimal edema. Most commonly seen in the temporal and parietal lobes.
• Desmoplastic infantile glioma (DIG): Variant of ganglioglioma that is usually seen in the first 2 years of life. Low-grade tumor with good prognosis. More commonly seen in the frontal and parietal lobes. Cystic mass with with a cortically based nodule. Nodule is iso- to high-attenuation, T2-hypointense, and enhances. Some may also have a calcified rim.
• Dysembryoplastic Neuroepithelial Tumor (DNET): Look for "bubbly" appearance on MRI.
• Pleomorphic Xanthoastrocytoma: Look for a cortically based nodule in a cystic lesion.

See related post on cystic brain masses.

References

Koeller KK, Henry JM. From the archives of the AFIP: superficial gliomas: radiologic-pathologic correlation. Armed Forces Institute of Pathology. Radiographics. 2001 Nov-Dec;21(6):1533-56