[Case of central nervous system lymphoma metastasized to breast after remission by methotrexate chemotherapy].

We report a case of primary central nervous system lymphoma (PCNSL) who responded well to initial systemic chemotherapy, but subsequently developed breast metastasis with local recurrence in the brain 27 months after complete remission. The 53-year-old female suddenly felt weakness in her left extremity. She was transferred to the emergency ward in our hospital. Neurological examination on admission showed disorientated state and mild hemiparesis. Brain MRI showed a well enhanced round lesion in the right basal ganglia with perifocal edema. A stereotactic biopsy of the tumor made a diagnosis of classic diffuse non-Hodgkin's B-cell type lymphoma. She received chemotherapy with a high-dose methotrexate under a condition of 20% of Karnofsky Performance Status (KPS). She enjoyed a useful life for about 5 years (KPS; 60-70%). Both recurrent and metastatic lesions responded poorly to various aggressive multiagent regimens of chemotherapy. An intensive initial treatment for the primary lesion and closely monitoring of the whole body at regular intervals are necessary for ensuring a long useful life.