Waldenström's macroglobulinemia: hyperviscosity syndrome and cryoglobulinemia.

Hyperviscosity syndrome (HVS) is a common manifestation of Waldenström's macroglobulinemia (WM). Patients with HVS have skin and mucosal bleeding, retinopathy with visual disturbances, and a variety of neurologic disorders. HVS can be diagnosed from physical examination by identifying the characteristic retinal venous engorgement ("sausaging") on funduscopic inspection. HVS can be accurately monitored with an Ostwald tube and reversed by plasmapheresis. Cryoglobulins precipitate or gel at temperatures < 37 degrees C and dissolve on re-warming. They may be composed of single or multiple components. Most cryoglobulins are mixed monoclonal IgMpolyclonal IgG immune complexes and many are associated with hepatitis C viral infection. Monoclonal macroglobulin autoreactive antibodies are included among the "IgM-related" disorders that influence the clinical presentation and natural history of WM.