A Case of Waldenstrom’s Macroglobulinemia Presenting as Worsening Neuropathy

Waldenstrom's macroglobulinemia (WM) is a rare lymphoplasmacytic lymphoma characterized by proliferation of monoclonal IgM-secreting B-cells, typically presenting with anemia, hepatosplenomegaly, and lymphadenopathy. We describe a case of WM manifesting as progressive neuropathy, initially attributed to degenerative spinal disease, for which the patient underwent treatment without clinical improvement. Further evaluation revealed a monoclonal M-spike on serum protein electrophoresis (SPEP) and endoneural IgM deposition on sural nerve biopsy. Bone marrow biopsy demonstrated lymphoplasmacytic lymphoma with MYD88 L265P mutation. The patient underwent six cycles of bendamustine-rituximab with partial neurological stabilization and a significant decline in IgM levels. However, neuropathy subsequently recurred, necessitating the initiation of zanubrutinib. This case highlights the diagnostic complexity of paraproteinemic neuropathy and emphasizes the importance of considering WM in the differential diagnosis of atypical neuropathy to ensure timely intervention and mitigate irreversible nerve damage.