Figure 4b. Primitive neuroectodermal tumor in a 17-year-old girl. The patient had been treated for acute lymphoblastic leukemia at 5 years of age. Axial contrast-enhanced CT scan (a), axial T2-weighted MR image (b), and coronal contrast-enhanced T1-weighted MR image (c) show a heterogeneous right hemispheric cerebral mass with cystic-necrotic components (arrow in a). Partial surgical resection demonstrated a primitive neuroectodermal tumor with posterior tumor progression. The patient did not survive.