This is a WHO grade 2-3 tumor. This is yet another relatively well circumscribed lesion, and one that may be associated with a fluid component, or a "cyst with nodule" morphology. This neoplasm is thought to arise from the superficial sub-pial astrocytes. This fits the empiric observation that many of these lesions present as cerebral hemispheric masses, with extension from the cortical surface, often producing a meningeal reaction and an enhancing "dural tail".