33 year old man
Posterior fossa tumour, resection: Medulloblastoma.
tissue fragments that are diffusely infiltrated by a densely cellular neoplasm
consisting of closely packed tumour cells with increased nuclear/cytoplasmic
ratio, oval, round or carrot-shaped hyperchromatic nuclei and scant cytoplasm.
The tumour cells form diffuse sheets with no pattern differentiation. There are
numerous apoptotic nuclei. In some areas the tumour cells tend to display clear
cytoplasm around central round nuclei. The mitotic activity varies, being
frequent in some parts of the tumour and less conspicuous in others. Most tumour
cells are strongly immunoreactive for synaptophysin and there are frequent areas
of intense immunoreactivity for neuron-specific enolase (NSE). Staining for
neurofilament protein is negative. A few GFAP-positive reactive astrocytes are
seen scattered in the tumour. The MIB-1 stain shows many cells in the mitotic
features images from this case