Brain lymphomas are aggressive cancers. They can have an extremely poor prognosis for patients. There is limited information about how they arise, why they behave in such a malignant fashion and why they don’t respond well to current treatments. We hope to find out more about the biology of lymphomas and want to find some clues about how they may be better treated. We will be using biopsy tissue of a number of brain lymphomas and performing DNA sequencing. This will help us find any significant mutations in important areas of DNA. These areas are likely to hold important information that should help to explain the behaviour of the tumour and may be targets for drug therapy. By performing this test on a number of brain lymphoma samples, we will be better able to see any recurring mutations in brain lymphomas and compare these to the mutations seen in lymphomas in other parts of the body. This will show us what differences there might be. We hope that this study will help in improving future diagnosis and treatment for this devastating disease.