Primary central nervous system lymphoma are characterized by macroscopically the tumor mass formation in the cerebral hemisphere including basal ganglia and corpus callosum and diffuse invasion particularly in the periventricular region, and microscopically lymphoma cells proliferation around the vessels and diffuse invasion into the brain parenchyma. Secondary involvement of central nervous system by systemic lymphoma are characterized by tumor cells invasion to the meninges and cranial and spinal nerve roots and tumor cells invade to the brain parenchyma along the perivascular space. Tumor nodule formation are very rare and tumor cells are not found in the lumen of the vessels. In the cases of extradural metastasis of systemic lymphoma, in addition to spinal cord compression, secondary circulatory disturbance, particularly venous congestion are also important factor for the spinal cord damages. In intravascular malignant lymphoma, not only tumor cells proliferation in the lumen of small sized vessels, but also secondary vasculitis and fresh and old thrombus formation are important for the development of multiple infarction of central nervous system. And spinal cords particularly in the levels of lumbosacral spinal cord are dominantly involved. Recently, according to the longness of clinical course of intravascular malignant lymphomatosis, cases with tumor mass are reported and these tumor mass are very similar to that of primary central nervous system lymphoma.