 Ms. ABC is a pleasant 60-year-old Caucasian female who was diagnosed in April 2008 with diffuse large B-cell lymphoma after she developed visual saltation, changes, and confusion.  Further staging revealed borderline mediastinal pretracheal lymphadenopathy but was otherwise unremarkable.  She began high-dose methotrexate in mid May 2008; courses of methotrexate have been complicated by prolonged methotrexate levels, mental confusion, and mania.  During cycle three, repeat MRI showed interval worsening of disease, and Rituxan was added to her regimen.  Ms. ABC had a repeat MRI on July 24, 2008 prior to this admission, which showed significant improvement in her CNS disease.