This is the report on the case of a 74 year old male patient who was admitted to hospital emergency because of a distended bladder, which was detected on an MRI. This MRI was performed because of an acute paralysis of the patient’s left leg. After various examinations we could conclude that the patient’s neurological symptoms were not due to metastases of a solid tumour as we expected, but to a primary spinal diffuse B-cell lymphoma. The central nervous system, and especially the spinal cord, are an extremely rare location for primary B-Cell lymphoma.