Fig. 1

Radiological and histopathological features the case Axial T2-weighted (a, d), axial (b, e) and coronal (c, f) T1-weighted images after gadolinium injection a, b, c: initial MRI, showing a thick linear enhancement within the right frontal lobe, and important peritumoral edema (high-T2-weighted signal), associated with thick and diffuse leptomeningeal enhancement. Frontal tumor enhancement showed restricted diffusion (image not shown). d, e, f: The follow-up MRI, 3 months after partial surgery, showing an increased solid tumor volume and larger peritumoral edema. The biopsy highlighted a dense proliferation composed of sheets of undifferentiated cells with numerous mitotic figures (g HPS, magnification × 400). Tumor cells were immunonegative for CD45 which highlighted some normal lymphocytes (h magnification × 400). Diffuse expression of CD43 (i magnification × 400) and CD117 (j magnification × 400). No immunoexpression for E-cadherin (k magnification 400x). High MIB1 labeling index (l magnification × 400). Scale bars represent 50 µm. HPS: Hematoxylin Phloxin Saffron