We review a case of a sensory-predominant presentation of Bing-Neel Syndrome (BNS), a rare complication of Waldenström macroglobulinemia (WM).

WМ is a distinct clinicopathologic entity demonstrating lymphoplasmacytic lymрhοmа in the bone marrow with an IgM monoclonal gammopathy in the blood. Patients typically present with symptoms related to the infiltration of the hematopoietic tissues or the effects of monoclonal ІgМ in the blood, such as anemia, thrombocytopenia, hepatosplenomegaly, lymphadenopathy, and rarely hyperviscosity. It has an incidence of approximately 3.0/1000000 people per year.

BNS is a rare presentation of WM where the IgM infiltrate the central nervous system which may occur at any time in the disease course. It has a prevalence of approximately 3.2%.

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A 67-year-old female with a history of asymptomatic WM diagnosed in 2010 presented in summer 2024 with a gradual decline in mobility and urinary retention (post void residual of 1,300 mL). She reported saddle anesthesia and clumsiness in the hands, as well as numbness in the hands and feet.
On exam, she was found to have lower more than upper limb weakness, hyperreflexia, hypertonia, and dysphagia.
Spinal cord MRI revealed T2 hyperintensity from C3-T1. Brain MRI showed a T2 hyperintense lesion in the cervicomedullary junction. None of the lesions had associated enhancement or diffusion restriction.
CSF analysis yielded normal cell count and protein levels but CSF flow cytometry revealed a lambda restricted CD10+ B-cell population. A diagnosis of BNS was therefore made.

Methylprednisolone 1g IV was administered for 3 days followed by initiation of Zanubrutinib.

Given the rarity of both WM and BNS, the clinical and radiologic presentation of our patient could have gone unrecognized. It is therefore reasonable to include BNS as an etiology for longitudinally extensive transverse myelitis.  This case demonstrates the importance of recognizing BNS early to initiate the appropriate management.