Fig. 4.

Radiological and histopathological features of case #6. Sagittal T2-weighted image (a) and FLAIR image (b) showing an infiltrative lesion of the pons with a central liquid part consistent with necrosis, with a peripheral enhancement of the necrosis on T1-weighted image with gadolinium injection (c), and intermediate signal on diffusion-weighted image (d) with partially restricted diffusion on apparent diffusion coefficient map (e). The biopsy highlighted two different histopathological components (f HPS, magnification × 50). The glial diffuse component (g HPS, magnification 400$\times$), associated with an ependymal component with rosettes (h HPS, magnification 400$\times$). Neurofilament immunostaining confirming the infiltrative pattern in the glial component (i magnification 400$\times$) and a more circumscribed pattern in the ependymal component (j magnification 400$\times$). Diffuse immunopositivity for Olig2 in the glial component (k magnification × 400), and partial expression of Olig2 in the ependymal component (l magnification × 400). Diffuse immunoexpression of H3K27M in both tumoral components (m–n magnification 400$\times$). Scale bars represent 1 mm (f) and 50 µm (g–n). HPS: Hematoxylin Phloxin Saffron