Uncommon Presentation of a Common Leukemia (Chronic Lymphocytic Leukemia): Case Report

The association of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) with usually low level of serum IgM monoclonal paraprotein is well recognized. We describe a rare case of a patient who developed overt IgM-related hyperviscosity syndrome after treatment for a diagnosis of CLL that was unresponsive to immunochemotherapy and to targeted therapies. Hyperviscosity syndrome, related to CLL-associated IgM paraprotein, is a very rare finding. High levels (> 3 g/dl) of serum IgM are mostly found in lymphoplasmacytic lymphoma-Waldenstrom macroglobulinemia (LPL/WM). In this patient, LPL was ruled out and diagnostic findings were consistent with only one clonal B cell population: CLL. It could be interesting understanding if ibrutinib therapy triggered IgM increase.