Bing-Neel Syndrome: Illustrative Cases and Comprehensive Review of the Literature.

The Bing-Neel syndrome is a rare neurological complication of Waldenström's Macroglobulinemia which results from a direct involvement of central nervous system by malignant lymphoplasmacytic cells. The clinical suspicion of Bing-Neel syndrome may be overlooked because neurologic symptoms are heterogeneous, nonspecific and sometimes underhand. A definitive diagnosis of Bing-Neel syndrome can be confidently made using brain and spinal cord magnetic resonance imaging as well as histopathology and/or cerebrospinal fluid analysis to confirm the neoplastic infiltration of central nervous system. The detection in the cerebrospinal fluid of patients with Bing-Neel syndrome of the MYD88 (L265P) somatic mutation, which is highly recurrent in Waldenström's Macroglobulinemia, proved useful for the diagnosis and monitoring of central nervous system involvement. Despite recommendations recently published, there is still no clear consensus on treatment of Bing-Neel syndrome, which includes systemic immunochemotherapy, intrathecal chemotherapy and brain irradiation as possible options. Ibrutinib, a Bruton kinase inhibitor approved for Waldenström's Macroglobulinemia, has been recently added to the therapeutic armamentarium of Bing-Neel syndrome due to its ability to pass the blood-brain barrier. However, prospective clinical trials are eagerly awaited with the aim to define the optimal treatment strategy. Here we describe four illustrative cases of Bing-Neel syndrome diagnosed and treated at our Institution and review the literature on this topic.