Lymphoplasmacytic Lymphoma (LPL)

• Neoplastic proliferation of B-cells ranging in spectrum from lymphocytes to plasma cells (typically involves the bone marrow, but can also involve the spleen and lymph nodes).  
• Bone marrow involvement
  • Nodular, diffuse, and/or interstitial
  • Small lymphocytes admixed with plasma cells and plasmacytoid lymphocytes
• IgM paraprotein
  • Sometimes result in a hyperviscosity syndrome(30%)
  • IgM and IgG paraprotein (minority)
  •  Some cases may be IgG or IgA. 
• Cryoglobulinemia (20% of WM)
• Coagulopathy (IgM binds to clotting factors)
• MYD88 (L265P) point mutation (>90%)
  • Results in up-regulation of NF-κB (promotes tumor cell survival). 
  • Not specific for LPL.
• LPL is a diagnosis of exclusion after other B cell lymphoid neoplasms with plasmacytic differentiation have been excluded.  
• IgM MGUS is now thought to be more closely related to LPL than plasma cell myeloma.

Most patients present with non-specific B-symptoms.  However, ~10% have hemolysis secondary to cold agglutinins (IgM binds to RBCs at temperature <37C).

Waldenstrom macroglobulinemia

• Cryoglobulinemia – precipitation of macroglobulins as temperatures <37C
• Bleeding – macroglobulins interfere with clotting factors
• Neurologic disturbances – secondary to increased blood viscosity
• Visual impairment – secondary to increased viscosity and hemorrhage

Immunophenotype

Morphology

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References