Refractory IgM AL amyloidosis with massive soft tissue tumors: Rescue with zanubrutinib. A case report

Waldenström macroglobulinemia (WM) is a rare indolent B-cell non-Hodgkin lymphoma with lymphoplasmacytic morphology, associated with immunoglobulin M (IgM) monoclonal gammopathy. The coexistence of WM and immunoglobulin light chain (AL) amyloidosis is an uncommon but well-described phenomenon. In patients suffering from IgM AL amyloidosis soft tissue involvement and neuropathy are more prevalent in in comparison to non-IgM patients. We present a case of 82-year old female with WM and intercurrent IgM AL amyloidosis, presenting with massive amyloidomas of both lower extremities, without significant cardiac and renal involvement. The patient was refractory to several lines of treatment and finally started on zanubrutinib monotherapy, with rapid and sustained very good partial hematologic response (VGPR) and clinical improvement.