Does the MRI confirm the CT impression? What features are helpful on MRI?
Absolutely. Diffusion restriction and homogeneous contrast enhancement are typical of primary CNS lymphoma.
True or false: Treatment with steroids (e.g. dexamethasone) prior to surgery is important to reduce swelling.
False: Although steroids will reduce swelling, lymphoma has a tendency to 'melt away' (unfortunately on temporarily) when steroids are administered, making diagnosis difficult. As such steroids should in most cases be avoided if the diagnosis is suspected, until histology is obtained.
MRI confirms the masses, which are of high T2 and low to intermediate T1 signal. A moderate amount of vasogenic oedema extends away from these masses into the white matter. The lesions demonstrate prominent restricted diffusion on DWI and intense homogeneous contrast enhancement.