This 35 y/o female with history of renal transplant presented with headaches. An MRI scan of the brain (sagittal T1 image with contrast) showed a large mass in deep supratentorial location. There is homogenous enhancement with contrast. A biopsy was diagnostic of diffuse large B-cell lymphoma. The incidence of CNS lymphoma has increased in recent years due to the increased number of immunocompromised patients (organ transplant, HIV infection, etc.). Case courtesy of Dr Bita Abbasi, Radiopaedia.org. From the case rID: 24239 The risk of post-transplant lymphoproliferative disorders (including primary CNS lymphoma) was much greater in allograft recipients who were on azathioprine-based regimens used earlier. With newer cyclosporine-based regimens, the risk is lower.