Primary central nervous system lymphoma (PCNSL) is a variant of extranodal non-Hodgkin lymphoma (NHL) that accounts for about 2% to 5% of all primary intracranial tumours with immunocompetent patients. It appears at a median age of 62 years. A standard of care for PCNSL patients has not been defined yet, but high-dose methotrexate (HD-MTX) is considered to be a beneficial chemotherapy in PCNSL treatment. Currently, HD-MTX is combined with numerous other chemotherapy drugs to improve outcomes of HD-MTX monotherapy. However, the impact of additional chemotherapy remains unclear, as there is evidence of a higher risk of adverse events (AEs) such as infective complications.