This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: CNS Tumors, Subject name: Surgery
[{'content': 'All of the following are true about Primary CNS Lymphoma except: \nSelect and explain. \nA. Most common type in immunocompetent patients is DLBCL, B. Glucocoicoids should be given before biopsy to reduce the risk of edema, C. Stereotactic biopsy is necessary for histologic diagnosis, D. High-dose methotrexate is used for the treatment', 'role': 'user'}, {'content': 'Answer: B \nExplanation: PCNSL: Has increased incidence in immunocompromised patients Most common type in immunocompetent patients is DLBCL Lymphoma anywhere in the body- Biopsy is needed for diagnosis In PCNL - Stereotactic biopsy is necessary for histologic diagnosis Steroids are C/I as they have cytolytic effect on tumor PCNL is also known as Ghost tumor - tumor disappear if given steroids Treatment: Chemotherapy - high dose Methotrexate', 'role': 'assistant'}]