Bing-Neel syndrome (BNS) is a rare manifestation of Waldenstrom’s Macroglobulinemia (WM) resulting from central nervous system infiltration by malignant cells. Herein, we report a case of BNS as the initial presentation of WM with both CNS and peripheral nervous system (PNS) involvement.

A 69-year-old woman was admitted with double vision, lower extremity weakness, sensory loss, pain and recurrent falls of 6 weeks duration. Her diagnostic work-up included MRI of the brain and spine showing cauda equina nerve root thickening and enhancement. An EMG showed findings of chronic and active motor axon loss in lumbosacral distributions. CSF analysis showed lymphocytic pleocytosis in addition to elevated protein and IgG index. Serum monoclonal protein testing revealed an IgM Kappa monoclonal gammopathy. Given the high suspicion for malignancy, CSF cytology and flow-cytometry were performed showing a B-cell lymphoproliferative disorder that was CD5 and CD10 negative. DNA testing on bone marrow biopsy detected an MYD88 L265P mutation confirming the diagnosis of WM. Further testing also revealed anti- myelin-associated glycoprotein (MAG) antibodies likely contributing to peripheral nerve and root involvement. Initial treatment with Rituximab, Methotrexate and then Ibrutinib was initiated which improved patient’s symptoms.

The neurological manifestations of WM can result from antibody-mediated neuropathy, hyper-viscosity syndrome, paraprotein deposition or rarely direct infiltration of tumor cells into the CNS. This patient had a combination of CNS and PNS involvement as an initial presentation of WM, an atypical manifestation of the disease. Stuttering progression and multiple diagnostic considerations, including cerebral infarction, CNS demyelinating disease, and CNS inflammatory disorders, delayed diagnosis. Gene testing on bone marrow cells confirmed diagnosis.