Acute deterioration in level of consciousness. Scanned on arrival in the emergency department.
Loading Stack -
0 images remaining
A large rounded mass is present in the posterior fossa, centered on the fourth ventricle. Centrally it is of high attenuation, consistent with haemorrhage. Following administration of contrast, moderate enhancement of the solid component is seen.
There is marked obstructive hydrocephalus and a little blood is also seen pooling in the occipital horns.
In a 30 year old the differential for a posterior fossa haemorrhagic mass is mainly between a haemangioblastoma and an ependymoma, although haemorrhage in both is quite uncommon. Pilocytic astrocytomas can rarely haemorrhage as can medulloblastomas, however in both cases the age group is a little atypical. Metastases would be unusual in a patient of this age.
The sections show multiple fragments of variably but up to moderately cellular tumour. Part of the tumour has an ependymal lining but the tumour has a distinctive pattern of moderately pleomorphic oval nuclei with speckled chromatin in a neurofibrillary background. Perivascular pseudorosetting is a prominent feature. In areas, true rosettes with lumens are also noted. Areas of tumour necrosis are not seen but there are focal collections of hemosiderin-laden macrophages and focal fibrosis is noted. An occasional mitotic figure is noted. The features are those of a classical ependymoma.
DIAGNOSIS : Posterior fossa tumour - ependymoma, WHO grade 2.