One year later the patient developed neurological symptoms, (a slow-down in mental and motility performance and a central defect of the VII cranial nerve) that led to a cranial CT examination and to the diagnosis of Primary Central Nervous System Lymphoma (PCNSL) arising from the left nuclei of the base, the nucleus caudatus, the anterior arm of the internal capsule, the insula and thalamus(stereotaxically diagnosed as CD45+, CD20+, CD3neg, CD10neg, Td Tneg, ki-67/MIB-1 = 90%), treated with L-VAMP multi chemotherapy and radiotherapy, resulting incomplete recovery. Here, MKI67 is linked to primary central nervous system lymphoma.