Primary neurolymphomatosis diagnosed by spinal nerve root biopsy.

Primary neurolymphomatosis is the direct infiltration of lymphomatous neoplastic cells into nerve roots and/or peripheral nerves. A 67-year-old man had a 24-month history of progressive and severe left lower limb neuropathic pain, ipsilateral ankle dorsiflexion weakness and gait disturbance. Gadolinium-enhanced MRI showed thickening and enhancement of the cauda equina, L5, S1 and S2 nerve roots.