Low-grade lymphoma with monoclonal plasmacytoid lymphocytes that secrete monoclonal IgM found in the bone marrow and other organ

Aetiology

• Exact cause unknown
• Personal/family history of autoimmune, inflammatory or infective disorders is a risk factor, especially Sjögren's syndrome and autoimmune haemolytic anaemia

Pathophysiology

• Lymphoplasmacytoid neoplasm
  • Clonal disorder of cells intermediate between a lymphocyte and a plasma cell
  • Characteristic IgM paraprotein

Clinical features

Tumour effects

• Lymphadenopathy
• Splenomegaly
• Marrow failure

Paraprotein effects

• Hyperviscosity, hyperviscosity syndrome - caused by IgM antibody being pentameric
  • Fatigue, visual disturbance, confusion, coma
  • Bleeding
  • Cardiac failure
• Neuropathy

B symptoms

• Night sweats
• Weight loss

Investigations

• Initial work up includes FBC, plasma viscosity, serum protein electrophoresis and immunofixation and quantification of IgM paraprotein by densitometry
• Bone marrow assessment - marrow infiltration by LPL