Bing–Neel syndrome: Two unexpected cases and a review of the literature

Abstract Waldenström macroglobulinemia (WM) is a lymphoplasmacytic lymphoma characterized by the proliferation of small B-lymphocytes in the bone marrow that produce monoclonal immunoglobulin M (IgM). We describe two patients with WM who presented with neurological symptoms due to infiltration of lymphoplasmacytoid tumor cells in the central nervous system, a condition known as Bing–Neel syndrome. A literature review revealed that this syndrome is rare and commonly missed in clinical practice due to its variable presentation and a lack of awareness or knowledge. Brain and spinal magnetic resonance imaging may show a focal mass or diffuse infiltration. The diagnosis of Bing–Neel syndrome requires proof of IgM or lymphoplasmacytoid cells in cerebrospinal fluid or in a brain biopsy. Treatment with intravenous and/or intrathecal chemotherapy and cranial radiotherapy is described in literature with generally poor outcome, although a combination of these therapies seems to improve outcome. Nevertheless, insufficient data are currently available to make general treatment recommendations.