Lymphoplasmacytoid proliferation resulting in a high level of a macroglobulin (IgM), elevated plasma viscosity and bone marrow infiltration.
0.5 per 100,000 per year.
Onset most commonly aged 60 years.
M > F
The abnormal proliferation of lymphoplasmacytoid cells produces high levels of IgM, which polymerises and results in increased plasma viscosity. Marrow infiltration may result in pancytopenia.
Hyperviscosity presents as weakness, tiredness, confusion and coma. Platelet opsonisation results in a functional deficiency and hence an increased risk of bleeding. Patients also often have peripheral lymphadenopathy. Marrow failure may lead to symptoms and signs of anaemia, recurrent infections and bleeding.
Full blood count: Haemoglobin, white cell count and platelets may be low or normal.
Bone marrow demonstrates lymphoplasmacytoid cell infiltration.
Protein electrophoresis shows an IgM paraproteinaemia.
Plasma viscosity is raised.
Chemotherapy produces a variable response. Plasmapheresis is used for symptomatic hyperviscosity.