A 38 year old HIV negative South African man was diagnosed in 2007 with stage IVB Hodgkin’s lymphoma. Conventional chemotherapy and radiotherapy had no effect, so in March 2007 he underwent an autologous stem cell transplant. Relapses in 2009 and 2010 resulted in two allogeneic stem cell transplants, after he was conditioned with fludarabine, cyclophosphamide, and anti-thymocyte globulin. After his second transplant he developed grade four graft versus host disease that affected the liver and gut, and in December 2010 he was started on an immunosuppressive regimen of prednisolone and ciclosporin. In June 2011 he re-presented with a one week history of fever, vomiting, and malaise, followed by severe headache and visual aura. On examination he was cachectic with mild ankle oedema and a fever (39.2°C). The rest of the examination was unremarkable. His peripheral white blood cell count was 0.7×109/L (normal range 4-11), neutrophils were 0.1×109/L (2-7.5), platelets 22×109/L (150-400), and haemoglobin 98 g/L (130-180). Liver function tests showed alanine transaminase 362 U/L (21-72), alkaline phosphatase 960 U/L (30-120), bilirubin 61 μmol/L (3-22; 1 μmol/L=0.06 mg/dL), and albumin 28 g/L (35-50). C reactive protein was raised at 2743 nmol/L (<45 nmol/L; 91 nmol/L=0.1 mg/L). In light of his neurological symptoms, he underwent magnetic resonance imaging (MRI) of the brain, the results of which are shown in fig 1⇓. Fig 1 Axial T1 weighted magnetic resonance image of the brain with gadolinium contrast ### 1 What does the contrast magnetic resonance image show? #### Short answer The contrast MRI of the brain shows a large ring enhancing lesion in the right parietal lobe. The …