Bing–Neel syndrome with a paravertebral mass

Bing–Neel syndrome, a rare neurological complication of Waldenström macroglobulinemia, is caused by the direct infiltration of malignant lymphoplasmacytic cells into the central nervous system. We report a patient who presented with back pain, weakness, lower extremity numbness, and gait disturbance accompanied by immunoglobulin M paraproteinemia and lymphoplasmacytic lymphoma in the bone marrow. Thoracic and lumbar magnetic resonance imaging revealed a long paravertebral mass around the spinal column, but the direct infiltration could not be proven. The patient was diagnosed with possible Bing–Neel syndrome and managed with bendamustine and rituximab. After chemotherapy, the patient's neurological and radiological findings improved. Magnetic resonance imaging should be considered when the Bing–Neel syndrome diagnosis is unclear.