There is a mass arising from the foramen of Magendie and extending into the cisterna magna and through the foramen magnum posterior to the medulla. This is isointense to brain parenchyma on T1-weighted sequence, heterogenous but predominantly hyperintense on T2, and enhances heterogeneously post contrast administration. Numerous tubular T2 flow voids surround this mass. It does not exhibit increased diffusion restriction. Some areas of susceptibility artefact in the superior aspect of the mass. There is no invasion of the adjacent brain parenchyma. The mass does not extend into the fourth ventricle. No evidence of hydrocephalus. No periventricular high signal. Brain parenchyma is otherwise unremarkable.
Enhancing posterior fossa mass as described above. Most likely diagnosis is that of an ependymoma. Absense of large flow voids, soft appearance and only intermediate enhancement make haemangioblastomas and choroid plexus papillomas less likely differential diagnosis.