First-line ibrutinib for Bing-Neel syndrome.

The authors present a case of an elderly man with a history of Waldenstrom macroglobulinaemia in remission who presented with progressively worsening gait abnormalities and falls for several months. His examination was notable for bilateral lower extremity weakness and an unsteady gait. Brain and spinal MRI showed focal leptomeningeal enhancement in the brain and spinal column. Lumbar puncture was performed and cerebrospinal fluid flow cytometry demonstrated a monoclonal CD5/CD10-negative, CD20-positive B-cell lymphocyte population consistent with a diagnosis of Bing-Neel syndrome. He was started on ibrutinib, an oral Bruton's tyrosine kinase inhibitor, and had marked improvement in his weakness and gait. Repeat imaging 2 months after starting ibrutinib showed improvement in his leptomeningeal enhancement. During subsequent follow-up, he continued to tolerate ibrutinib and had a sustained clinical response.