[Successful treatment of Bing-Neel syndrome using combination therapy with fludarabine and rituximab]

Bing-Neel syndrome is known as Waldenström's macroglobulinemia with central nervous system infiltration by neoplastic lymphoplasmacytoid and plasma cells. A 74-year-old man was admitted because of progressive cognitive impairment. Serum immunoelectrophoresis showed a monoclonal IgM-kappa component. Bone marrow aspiration revealed 59% small lymphocytes showing plasmacytoid differentiation. Bone marrow flow cytometry disclosed a population of kappa light-chain positive lymphoid cells expressing CD19, CD20, CD38, and CD138. Magnetic resonance imaging of the brain demonstrated gadolinium-enhancement in the right temporo-parieto-occipital meninges with sulcal enhancement. Cerebrospinal fluid cytology showed a population of lymphoplasmacytoid cells, positive for CD19, CD20, CD25, and kappa light-chain. Based on these findings, Bing-Neel syndrome was diagnosed. Although combination chemotherapy consisting of intrathecal methotrexate and oral cyclophosphamide was started, his symptoms continued to worsen. Then, we initiated treatment with a regimen consisting of fludarabine/rituximab (FR). After 6 courses of this FR regimen, a complete remission was achieved. Our case suggests the FR regimen to potentially be an effective treatment option for Bing-Neel syndrome of the scattered type.