Fig. 3

Histomolecular features of HGG-MYCN. a Diffuse and solid proliferation with several nodules infiltrating the brain parenchyma (arrowheads) and the leptomeninge with large vessels (asterisk) (Case 2, HPS, × 100 magnification). b Dense proliferation of tumour cells organized in nodules following Virchow-Robin spaces around capillaries (Case 2, HPS, × 250 magnification). c Highly cellular and undifferenciated proliferation composed of alternating fascicles and nodules (Case 2, HPS, × 250 magnification). d Highly malignant tumor with microvascular proliferation (arrowhead) and necrosis (Case 2, HPS, × 400 magnification). e Embryonal proliferation composed of hyperchromatic cells presenting anisocaryotic nuclei with numerous apoptotic bodies (Case 3, HPS, × 400 magnification). f Elevated proliferation index (Case 2, MIB, × 400 magnification). g Diffuse expression of Olig2 (Case 2, × 400 magnification). h Focal expression of GFAP by tumor cells (Case 2, × 400 magnification). i Expression of neurofilament in numerous tumor cells (Case 3, × 400 magnification). j Nuclear accumulation of p53 (Case 2, × 400 magnification). k PTEN loss of expression in tumor cells (endothelial cells as positive internal controls). l High-level of MYCN amplification by FISH analysis with MYCN locus in green signals and control centromeric in red signals (Case 4). Black scale bars represent 1 mm (a), 100 μm (b) and 50 μm (C to K)