Figure 12a. Pleomorphic xanthoastrocytoma in a 13-year-old boy with neurofibromatosis I and headaches. (a) Nonenhanced axial CT image shows a heterogeneous mass (arrows) of the right frontal lobe with both cystic and soft-tissue components. A mild amount of surrounding vasogenic edema (arrowheads) is present. (b) Axial T1-weighted MR image obtained at a slightly different level than in a shows that the mass does not extend to the cortical surface. Soft-tissue (S) and cystic (C) components are again noted. (c) Axial T2-weighted MR image shows mild low signal intensity of the soft-tissue portion of the mass, whereas the cystic portions are hyperintense. Small "fingers" of vasogenic edema surround the mass. (d) Contrast-enhanced axial T1-weighted MR image shows intense enhancement of the soft-tissue portion of the mass with rim enhancement of the cystic margin.