Lymphomas may cause polyradiculopathies by several pathogenic mechanisms. However, such a presentation of a nasal-type NK (natural killer) cell lymphoma is rare. We report a previously healthy man who developed acute, axon-loss radiculopathies and cranial neuropathies. Despite the lack of a nasal or midline facial mass, cerebrospinal fluid cytologic and flow cytometric immurtophenotypic studies disclosed that the patient's rapid demise was the result of a nasal-type NK cell lymphoma with leptomeningeal involvement