A Cold and Viscous Clue: Waldenström Macroglobulinemia Presenting With Secondary Cold Agglutinin Syndrome and Hyperviscosity Syndrome

Waldenström macroglobulinemia (WM) is an indolent mature B-cell lymphoproliferative disorder defined by bone marrow infiltration by lymphoplasmacytic lymphoma (LPL) and an associated serum monoclonal immunoglobulin M (IgM) gammopathy.In this case report, we describe a patient presenting with two serious and rare IgM-mediated complications of WM that require urgent treatment: secondary cold agglutinin syndrome and hyperviscosity syndrome.With prompt diagnosis and therapeutic plasma exchange, the patient's IgM-mediated complications improved, with a marked reduction in serum IgM and resolution of hyperviscosity-related symptoms.This highlights the importance of recognizing the possible complications of an otherwise indolent disease.