Fig. 1

Illustration of the clinical case. a. Sagittal cranial MRI of the 22-month-old boy showing the initial tumor in the 4th ventricle (left, single arrow) and signs of massive meningeosis 3 weeks later (right, multiple arrows). b. HE staining of the initial tumor showing typical anaplastic morphology of the tumor cells. Insert: medulloblastoma cells from the CSF (Pappenheim-staining)