Primary Central Nervous System Lymphoma (PCNSL) is a rare form of aggressive extranodal non-Hodgkin's lymphoma. Treatment modalities for PCNSL cases have developed in the last few decades, with no universally-agreed consensus regarding the optimal treatment regimen to date. We report a 61-year-old patient with right limb weakness, decreased consciousness, and a history of recurrent seizures. The patient had a MSCT examination on the head, with and without contrast, showing an enhancing solid mass with perifocal edema around it in the right frontal lobe. On immunohistochemical histopathological examination of cerebral material, the conclusion was Non-Hodgkin Lymphoma B cell type high grade. The patient was diagnosed with Non-Hodgkin Lymphoma Cerebral B cell type high grade. The patient was subjected to chemotherapy with HD-MTX (high-dose methotrexate) and rituximab therapy for 6 cycles, in combination with dexamethasone. Chemotherapy evaluation after 6 cycles showed a complete response to therapy without any drug side effects from chemotherapy with consciousness returning to normal and limb weakness gradually improving.