[A case of neurolymphomatosis presented as cauda equine syndrome accompanied with M-proteinemia].

A 63-year-old man developed a syndrome of cauda equine, with the numbness which is a left lower extremity from the left buttocks, weakness of left leg, and a dysfunction of bladder and bowel. Enhanced MRI revealed the enhancement of lower cauda equine, and a nerve conduction test revealed decreased F-wave persistency in the tibial nerve and increased F-wave latency in the peroneal nerve on the both sides. M-proteinemia was admitted and myeloma was suspected. By a biopsy of a vertebral arch, we diagnosed with diffuse large B-cell lymphoma. We treated with dexamethasone and R-CHOP (rituximab, cyclophosphamide, hydroxydaunorubicin, oncovin, prednisone (prednisolone)), then the symptom was improved. In case of caude equine syndrome with M-proteinemia, a possibility of the malignant lymphoma should also be considered.